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1. none Comment line SUBS substrate parameters Name Default Units Description PH 1 0 10 2 em Initial uniform phosphorus concentration BO 1 0 10 2 cm The same parameter for boron doping AS 1 0 10 2 cm The same parameter for arsenic doping OR 100 none Lattice orientation COMM Comm none Comment line SOLV numerical solution control Name Default Units Description IB 1 none Batch mode switch If IB 1 the default then run without plotting after each processing step batch mode IT 100 none Maximum number of iterations for the linear solver RS 102 none Residual convergence criterion for the linear solver RL 103 none Relative residual criterion for the linear solver CO 10 2 cm Value of the impurity concentration considered to be a back ground COMM Comm none Comment line 42 MICROTEC 3 02 User s Manual Chapter 4 Process Simulation PHDE phosphorus deposition Name Default Units Description XD 1 um Position of the mask edge for a surface deposition of the dopant In this case the surface acts as source with a constant concentration The predeposition occurs in the surface region from 0 to XD if XD is positive or from XD to XX if XD is negative If XD is 0 or omitted there is no predeposition If XD is larger then XX the dopant is deposited throughout
2. Viewing a fragment MESH NX 50 NY 45 XX 5 YY 3 COMM Fragment view FRAG X0 0 DX 0 SY 0 OV 1 IF MOS OUD Symmetrical device using one fragment MESH NX 70 NY 40 XX 2 5 YY 1 COMM NMOS Transistor FRAG X0 1 6 DX 0 7 SY 1 OV 1 IF EXMOS OUD Vertical BJT with substrate collector MESH NX 150 NY 40 XX 5 Y Y 2 5 COMM Vertical BJT FRAG X0 4 5 DX 1 SY 0 OV 1 IF BUR OUD FRAG X0 1 DX 1 SY 1 OV 0 IF EMIT OUD Vertical BJT with a buried layer MESH NX 200 NY 40 XX 8 Y Y 3 5 COMM Planar transistor MICROTEC 3 02 User s Manual 57 Device formation Chapter 5 FRAG X0 4 DX 1 SY 0 OV 1 IF BUR OUD FRAG X0 1 DX 1 SY 1 OV 0 IF EMIT OUD L Device MESH NX 200 NY 40 XX 10 Y Y 2 5 COMM I2L device FRAG X0 1 DX 1 SY 1 OV 1 IF BUR OUD FRAG X0 10 DX 1 SY 1 OV 0 IF EMIT OUD 58 MICROTEC 3 02 User s Manual DEVICE SIMULATION MICROTEC 3 02 User s Manual 59 Chapter 6 Device Simulation 6 1 Introduction A number of software tools are available for two dimensional semiconductor device simulation Conventionally they use Newton like methods and this results in numerical instability and relatively high memory requirements Recently new methods for the linearization of the semiconductor equations were proposed 3 4 5 permitting the efficient solution of the nonlinear semiconductor equations The methods use the decoupled or Gummel like scheme 14 signif
3. where Process Simulation Chapter 4 Here n is the electron concentration and n is the intrinsic carrier concentration B s Eg 44 1 Nol lT 4 4 From 2 and 3 we obtain E Ta _yzve 4 5 Z Assuming that the Einstein relation S Kd D is valid the diffusion equation transforms to g Mz LT Kk q Y ZYC J D VC ZC 4 6 In the case of one impurity the drift can be taken into account by introducing a multiplicative fac tor for the diffusivity 3 but for several impurities the following system of coupled equations must be solved SE Y ZYC V DVC DZ C l 4 7 dt 2 Lac 4n k Diffusion coefficient The diffusivity of arsenic and boron accounting for single charged defect influence 1s chosen in the form 3 4 5 D a 4 8 where n for arsenic N P for boron D and Ep are the intrinsic diffusion coefficient Lars ee Ok Ok 1 1 34 MICROTEC 3 02 User s Manual Chapter 4 Process Simulation and activation energy of the k th impurity respectively The parameter B defaults to 3 for boron and 100 for arsenic The phosphorus diffusivity was chosen as in 5 6 and accounts for the diffusion via neutral and single and double negatively charged vacancies Dp D en 0 z exp D E op 4 9 Oxidation enhanced diffusion The diffusivity during oxidation is modified depending on the rate of oxidation in order to describe the oxidation enhanced or oxidat
4. Device Simulation YAMA Yamaguchi mobility model U N E E b N E 1 G CF sal E Ve Hi l EE Chapter 6 1 UE 1 N ES p W E bol 1 z Cale Nt S Symbol Name Default Units Description Ho UMNO 1 410 cm2 Vs Maximum electron mobility S SN 350 0 none Doping concentration factor for electrons Nn RSN 3 0 1016 cm Reference doping concentration for electrons o ALN 1 54105 cm V Perpendicular electric field factor for electrons Von VSN 1 036107 cm s Saturation velocity for electrons G GN 8 8 none Parallel electric filed factor for electrons Von VCN 4 9 10 cm s Phonon velocity fitting parameter Lo UMPO 480 0 cm2 V s Maximum hole mobility S SP 81 0 none Doping concentration factor for j electrons N RSP 4 010 em Reference doping concentration for holes a ALP 5 35 10 cm V Perpendicular electric field factor E for holes Vsp VSP 1 2107 cm s Saturation velocity for holes 76 MICROTEC 3 02 User s Manual Chapter 6 Device Simulation Symbol Name Default Units Description G GP 1 6 none Parallel electric filed factor for holes Ds VCP 2 928 106 cm s Phonon velocity fitting parameter LOMB Lombardi surface mobility model Ne CB ee ie Ta CoN 1 shoe A Hac Ep T Bee 2 gt Hsr u Hac Hp Us B E Umax T Ho Hi T je N T yot eU gt T 300 HyCN T Ho Ha
5. and 500 s for 900 C and lower For an accurate eval uation on a fine mesh the recommended value is 2 10 times lower than the one above Use a smaller TAU if the number of nonlinear iterations exceeds 7 OX 1 none Type of annealing atmosphere 1 dry oxygen 2 wet ambient POX 1 Atm Pressure of the oxidizing ambient oxygen or vapor XO 0 um Position of the oxidation mask The oxide grows in the region from 0 to XO if XO is positive and from XO to XX if XO is negative To get a uniform oxide make XO a few times greater than XX U0 0 001 um Initial uniform oxide thickness microns It affects the rate of the oxide growth COMM Comm none Comment line ANNE annealing parameters Name Default Units Description TC 1000 C Temperature of annealing centigrade TM 1000 S Time of annealing in seconds 44 MICROTEC 3 02 User s Manual Chapter 4 Process Simulation Name Default Units Description TAU 100 S Initial time step in seconds The recommended value is 30 s for a temperature of 1200 C 100 s for 1100 C 200 s for 1000 C and 500 s for 900 C and lower For an accurate eval uation on a fine mesh the recommended value is 2 10 times lower than the one above Use a smaller TAU if the number of nonlinear iterations exceeds 7 COMM Comm none Comment line EPIT epi layer formation Name De
6. see below is on the first line of three numbers in the status bar shows the val ues of the X Y and Z coordinates at the current mouse position The bottom line shows the num bers of current X and Y sections and the overall dimension of the grid Map Tool Bar The tool bar is the line of buttons just below the main menu and just above the plot window The first four buttons are used to move the current X and Y sections forward and backward This can also be done by using the arrows on the keyboard The Log Z button is used to switch to and from a logarithmic scale of the Z coordinate The next three buttons are used to open SibGraf Map window with the same data and SibGraf 2D windows with the current X and Y sections The last is the Probe button used to switch on and off the probe mode see Help on Map Status Bar above 3 5 Annotate All of SibGraf 2D 3D and Map windows have Annotate item in their main menu Two types of 28 MICROTEC 3 02 User s Manual Chapter 3 MicroTec Graphics SibGraf annotate objects can be created Line and Text Annotate objects are associated with the real X and Y coordinates and not with the window or screen position and therefore move with respect to the window when such operations as zooming or change of the size of the window are per formed When the subitem Line is chosen the user can draw a line consisting of a number of straight seg ments defining the start and end points o
7. MergIC program for MERGing fragments of IC elements e SemSim two dimensional steady state SEMiconductor device SIMulator e SibGraf interactive 3D and 2D graphics MicroTec is a highly robust 2D semiconductor process device simulation package which can be run on IBM PCs and compatibles with a reasonable CPU time and low memory requirements 2 2 Running MicroTec MicroTec main menu has two tabbed pages Select Project page and Project Settings page that can be switched by clicking on the respective tab Select Project page The first page of the MicroTec main menu called the Select Project shown below comprises the following objects e Run Bar with Run 2D Output 3D Output Help and Exit buttons e Edit Bar with Add Update Copy and Delete buttons e Name Text Box showing the current project name e Method Text Box showing the simulator used for the current project Project List Window showing the list of available projects Project Description Window with a brief description of the current project e Method Description Window with a brief description of the current project simulator MICROTEC 3 0 ggi EE oe e Select Project Project Settings Name LOCOS process LOCOS oxidation simulation Batch test Drain Gate formation new Drain Gate f tion test tain Gate formation tes Method LOCOS process LOCOS process test MerglC
8. MerglC new Schottky diode 2D diffusion oxidation Update Select Project MICROTEC 3 02 User s Manual 15 MicroTec User Interface Chapter 2 To select a project in the project list window on the Select Project page click the left mouse button at a project name The corresponding project and simulator name will be appear in the Name and Method text box respectively If you need to change a project name or project description edit the text in the respective window and click Update button If you need to start a new project type a name of the project in the Name window select a method in the Method text box and click the Add button A project with default settings will be created Change current page to the Project Settings page and edit parameters as described in Section Project Settings page on page 16 Another way of starting a new project is to copy an existing project by clicking the Copy button and then to modify directives parameters on the Parameter Settings page A new project with copy at the name end will be created To modify the project name change the name in the Name text box and click the Update button in the main MicroTec window To run a simulation click the Run button After the simulation is complete you may display the results by clicking on 2D Output or 3D Output button for plotting IV curves or
9. PHOT Photogeneration well Name Default Units Description RATE 1 1020 cm3 s Maximum photogeneration rate in the well XLFT 0 um Left edge of the doping well XRGT 1 um Right edge of the doping well YTOP 0 um Top of the doping well YBOT 1 um Bottom of the doping well ALX 0 001 um Characteristic length in X direction ALY 0 001 um Characteristic length in Y direction 84 MICROTEC 3 02 User s Manual
10. at 300 K Eva EGAL 4 73104 eV Value of Alpha in the formula for the bandgap width E EGBE 6 36 10 OK Temperature correction term in the formula for the bandgap width N 300 ENC3 2 810 cm The semiconductor conduction band density of states 74 MICROTEC 3 02 User s Manual Chapter 6 Device Simulation Symbol Name Default Units Description N 300 ENV3 1 04101 em The semiconductor valence band density of states Veen VOBG 0 009 eV The voltage parameter in the bandgap narrowing model No CONB 1 0 10 7 cm The concentration parameter in the bandgap narrowing model Chay CNSB 0 5 none The constant parameter in the bandgap narrowing model PERM Dielectric permittivity Name Default Units Description EPSD 3 9 none The relative dielectric permittivity of the oxide EPSS 11 8 none The relative dielectric permittivity of the semiconductor WORK Semiconductor work function Name Default Units Description FIS 4 17 eV Semiconductor electron affinity MOB Mobility models This directive contains four unique subdirectives CONM YAMA LOMB and BIPO CONM Constant mobility model Symbol Name Default Units Description Uno UMNO 1000 cm2 V s Constant mobility for electrons Bro UMPO 500 cm V s Constant mobility for holes MICROTEC 3 02 User s Manual
11. back and delete the current curve shown in yellow color More information is available in Section 2D Tool Bar on page 23 SibGraf 2D File Curve View Annotate Help EEEE lofe DCE fo NES 9 9977e 19 File Open Open a picture file previously created by this program Load Load data from a file containing 2D data e g IV curves MICROTEC 3 02 User s Manual 21 MicroTec Graphics SibGraf Chapter 3 Save Save the plot to the picture file that is currently open If there is no picture file that is cur rently open if the Load function was used instead then this function will behave as the Save As function described below Save As Save the plot to a picture file A window will be provided to allow you to choose the file name Clear Clear the plot window Print Print the plot to a printer or to a Postscript file New Window Open new Sibgraf 2D window Exit Close the window Curve Add Open a window which displays the information about the current data file A file must have been previously loaded with the Load command under the File submenu for this to work A new window appears showing the information extracted from the data file which has been loaded It enables the user to select curves to be shown in the plot window The first line of this window shows the current family number and name and allows the user to switch between families Odd family numbers correspond to th
12. device design A flexible and easy to use graphic interface allows the user to output results of the process device simulation on essentially any printer or plotter or into a file Despite apparent simplicity MicroTec covers all basic needs for semiconductor process device design complemented with efficient and flexible graphics tools It is much easier to use than any other tool of its kind MicroTec is a must for those who want to understand physics of semicon ductor devices without knowing much about computers or numerical methods and who do not have much time for learning new process device simulation tools MicroTec is an excellent tool for managers R amp D engineers students professors and researchers and can be referred to as a TCAD calculator MicroTec is based on the diffusion drift model and the present version does not include energy balance It employs finite difference technique on a rectangular auto adjusting mesh Only steady state analysis is available in the present version of MicroTec Physical models mobility life time recombination and impact ionization implemented in MicroTec are essentially the same as those used in the widely used commercial simulators Technical Parameters MicroTec 3 02 is a true 32 bit Windows application and can be run on any PC 386 or higher MICROTEC 3 02 User s Manual 9 Getting Started Chapter 1 MicroTec 3 02 uses dynamic memory allocation There is no memory threshold so it can be
13. elec trons E mn ECNM 6 49 104 V cm Critical electric field in the perpendicular electric field mobility for electrons der VSTN 1 07 107 cm s Electron saturation velocity MICROTEC 3 02 User s Manual 79 Device Simulation Chapter 6 Symbol Name Default Units Description V a UNN 2 3 none Exponent of normalized temperature in the numerator for electrons 3 XIN 3 8 none Exponent of normalized temperature in the denominator for electrons o ALPN 0 733 none Exponent of impurity concentration for electrons Gr GSRN 1 0 none Low field reduction factor for electron msi mobility BETN 2 0 none Exponent used in the field dependent elec B p p tron mobility for parallel electric field TROA UMPM 49 7 cm 2 V s Minimum hole mobility ee UMPX 479 cm V s Maximum hole mobility Nas CRFP 1 61017 cm Reference impurity concentration for holes Es ECPM 1 87 104 V cm Critical electric field in the perpendicular electric field mobility for holes valo VSTP 1 06 107 cm s Hole saturation velocity v UNP 2 2 none Exponent of normalized temperature in the P numerator for holes E XIP 3 7 none Exponent of normalized temperature in the P denominator for holes a ALPP 0 7 none Exponent of impurity concentration for holes Carto GSRP 1 0 none Low field reduction factor for hole mobility B BETP 1 0 none Exponent used in the field dependent hole mobility for para
14. input files A few examples of typical processing runs are presented in this section MOSFET fragment Substrate with orientation lt 111 gt is doped initially with boron at 101 cm Boron is implanted at 60 KeV and 6 10 ions cm in the whole region and then arsenic is implanted at 100 KeV and 101 ions cm through the mask and annealed at 1000 C for 60 minutes in an inert ambient MESH NX 20 NY 20 XX 1 Y Y 0 7 IM 1 COMM MOSFET SUBS PH 1E12 BO 1E15 AS 1E12 OR 111 BOIM XM 2 DZ 6 E 11 EN 60 ASIM XM 0 5 DZ 1 E15 EN 100 ANNE TC 1000 TM 3600 TA 600 OX 0 MICROTEC 3 02 User s Manual 51 Process Simulation Chapter 4 LDD MOSFET fragment Boron and arsenic are implanted as in the above example into the same substrate Then the mask is shifted by 0 35 microns and LDD arsenic is implanted at 100 KeV and 10 ons cm Finally the wafer is annealed at 1000 C for 60 minutes MESH NX 20 NY 20 XX 1 Y Y 0 7 IM 1 COMM LDD MOSFET SUBS PH 1E12 BO 1E15 AS 1E12 OR 111 BOIM XM 2 DZ 6 E 11 EN 60 ASIM XM 0 6 DZ 1 E15 EN 100 ASIM XM 0 25 DZ 1 E12 EN 100 ANNE TC 1000 TM 3600 TA 600 OX 0 Fragment with LOCOS Substrate is initially doped by boron at 101 cm Arsenic is implanted at 200 KeV and 1015 ions cm in the left side of the region Then boron is implanted at 200 KeV and 101 ions cm through another mask in the right side of the region Annealing follows at 1100 C for 1 hour in a wet oxid
15. the fragment surface CS 101 cm Surface concentration of the dopant for the deposition May be omitted if XD is omitted COMM Comm none Comment line BODE boron deposition The same parameters are used as in the directive PHDE ASDE arsenic deposition The same parameters are used as in the directive PHDE PHIM phosphorus implant Name Default Units Description XM 1 um Position of the implantation mask edge The dopant is implanted through the window from 0 to XM if XM is posi tive and from ABS XM to XX if XM is negative For uniform implantation all over the domain XM should be much greater then XX Make it 0 or omit it to suppress the implantation DZ 10 2 cm Implantation dose ignored if XM 0 EN 40 KeV Implantation energy up to 1000 COMM Comm none Comment line BOIM boron implant MICROTEC 3 02 User s Manual Process Simulation Chapter 4 The same parameters are used as in the directive PHIM ASIM arsenic implant The same parameters are used as in the directive PHIM OXID oxidation parameters Name Default Units Description TC 1000 E Temperature of oxidation centigrade TM 1000 S Time of oxidation in seconds TAU 100 S Initial time step in seconds The recommended value is 30 s for a temperature of 1200 C 100 s for 1100 C 200 s for 1000 C
16. used even on a computer with only 1 Mbyte memory if the mesh size is not larger than about 2 000 nodes Other commercially available tools typically require about 20 Mbyte memory for a mesh size limited by 3 500 nodes MicroTec 3 02 device simulation tools require about 8 Mbytes of memory for a 20 000 node mesh Typical CPU time for one IV point is less than 1 minute on a PC 486 when using 1 000 nodes For the process simulation tool about 4 Mbytes of memory is required for a 20 000 node mesh Simulation of a typical technological route requires 1 10 minute CPU time on a PC 486 The most remarkable features of MicroTec are dramatically reduced required memory absolute numerical stability almost arbitrary changes of contact voltages even with impact ionization high speed and very easy to use Graphical User Interface 1 2 Installing MicroTec Read about the latest changes in the Installation procedure in the readme txt file on the installa tion Disk You would need about 4 Megabytes of disk space to install MicroTec 3 02 If your system is Windows 95 reboot the computer in DOS mode before the installation If your system is Windows NT refer to read_nt txt file on the floppy disk Insert MicroTec Disk into a floppy drive Change your current drive to the floppy drive Type install and press lt Enter gt File INST PAS will be created on the floppy disk Create directory C MICROTEC on your hard disk Copy all files from t
17. 3 107 cm s Fitting parameter for perpendicular electric filed C COP 8 84103 Fitting parameter for perpendicular electric filed and doping concentration 9 CPOP 3 17102 none Exponent of the doping concentration parameter Ho UOP 44 9 em2 Vs Minimum electron mobility Umax UMAP 470 em2 Vs Maximum electron mobility Ly ULP 29 cm2 Vs Concentration correction term C CRP 22310 em Critical doping concentration C CSP 6 10102 em Critical doping concentration in the correction term 78 MICROTEC 3 02 User s Manual Chapter 6 Device Simulation Symbol Name Default Units Description P PCP 9 23 19 6 cm s Concentration correction of the minimum mobility a ALPP 0 719 none Exponent in the concentration factor B BETP 2 0 none Exponent in the concentration correction factor Y GAMP 2 2 none Temperature factor exponent DELP 2 051014 V s Acoustic term parameter bas BESP 1 0 none Exponent in the saturation velocity Von VSAP 1 07 107 cm s Saturation velocity BIPO Bipolar mobility model Hs n N E E G surf n u min n pr Su Qn t a a 300 WW a _ min 1 300 ln E gt 1 Hg E Bn Br p V Ep Ej Us N efi A sat n Symbol Name Default Units Description Ha min UMNM 55 2 em2 Vs Minimum electron mobility Mr max UMNX 1430 cm V s Maximum electron mobility Noia CREN 1 07 10 7 cm Reference impurity concentration for
18. 3D contour plots of two dimensional distributions of various variables such as electrostatic potential carrier and current densities Fermi quasi potentials electric field components etc See Section Micro Tec Graphics SibGraf on page 19 for more information on the MicroTec graphics Project Settings page To modify project settings click on Project Settings tab The other page of the main MicroTec menu will appear showing a Project Tree containing directives subdirectives and parameters Click the left mouse button on a folder symbol to open it Double click the left mouse button on a parameter to edit it MICROTEC 3 0 Select Project Project Settings Project tee cj LOCOS process P0000010 3D E Domain and Mesh E Numerical Solution E Substrate E Boron implant Oxidation E Arsenic implant E Annealing Select Project To modify the tree structure click a directive subdirective parameter by the left and then the right mouse button A new window pops up allowing you to Delete Copy Insert or Add a new entry 16 MICROTEC 3 02 User s Manual Chapter 2 MicroTec User Interface MICROTEC 3 0 Select Project Project Settings E LOCOS process P0000010 3D E Domain and Mesh E Numerical Solution Delete E Substrate Boron implant Insert Directive E Oxidation Add Subdirective E Arsenic implant Add Parameter E Annealing feces process Boron impla
19. 8 3 6 Zooming 29 4 Process Simulation 31 4 1 Introduction 33 4 2 Physical model 33 4 3 Simulation algorithm 38 4 4 References 38 4 5 Running SiDif 39 4 6 SiDif input file 40 4 7 SiDif basic directives 41 MESH computational domain and mesh parameters 41 SUBS substrate parameters 42 MICROTEC 3 02 User s Manual iii CONTENTS SOLV numerical solution control 42 PHDE phosphorus deposition 43 BODE boron deposition 43 ASDE arsenic deposition 43 PHIM phosphorus implant 43 BOIM boron implant 43 ASIM arsenic implant 44 OXID oxidation parameters 44 ANNE annealing parameters 44 EPIT epi layer formation 45 4 8 SiDif model parameter directives 45 BAND Bandgap and intrinsic carrier concentration 45 DIFF Diffusivity of Arsenic Boron and Phosphorus 46 OED Oxidation enhanced diffusion 47 DROX Dry oxidation kinetic constants 48 WEOX Wet oxidation kinetic constants 48 LOCO Local oxidation bird s beak formula parameters 49 SEGR Segregation parameters 50 4 9 Examples of SiDif input files 50 5 Device formation 53 5 1 Introduction 55 5 2 Running MergIC 55 5 3 MergIC input file 55 MESH Domain and mesh 56 FRAG fragment description 56 5 4 Examples of MergIC input file 57 6 Device Simulation 59 6 1 Introduction 61 6 2 Basic System of Equations 61 6 3 Numerical technique 66 6 4 References 66 6 5 Running SemSim 67 6 6 SemSim input file 68 BAS Basic directives 69 MESH Domain and mesh param
20. Batch batch mode simulation of any number of process and or device simulations MICROTEC 3 02 User s Manual 17 MicroTec User Interface Chapter 2 18 MICROTEC 3 02 User s Manual 3 MICROTEC GRAPHICS SIBGRAF MICROTEC 3 02 User s Manual 19 Chapter 3 MicroTec Graphics SibGraf 3 1 Introduction SibGraf is a fast and user friendly software tool for plotting I V curves and two dimensional dis tributions of the electrostatic potential carrier and current densities Fermi quasi potentials gen eration rate and electric field components It is menu driven and includes on line help SibGraf generates 3D plots contour lines color maps 2D cross sections of 3D plots and 2D plots for I V data 3 2 SibGraf 2D Output This function allows you to plot any column or a product of any two columns or a ratio of any two columns as a function of any column in the 2D data file The 2D data file is generated by SemSim and represents IV data and transconductance data When you click on 2D Output but ton in the main MicroTec window a new window pops up with five menu choices File Curve View Annotate and Help The subtopics available under these menus are described below To zoom a portion of the graph use the left muse button as described in section Zooming below You may also use Annotate command which is also described below The Tool Bar buttons allow you to change the current point and curve switch to log scale and
21. Close the window Surface Source Opens a window which shows the data source for the current plot If the current plot was invoked through the Open function Source is the only subitem under Surface If the file with 2D distribution data was loaded through the Load function all sur faces contained in that file are listed after the item Source Any of these surfaces may be plotted View Axis Limits Opens a window where the user can assign ranges for horizontal and vertical axes Options See Help on 2D Options in Section View on page 23 Set Contours see help on Map Set Contours in Section Map Set Contours on page 28 Rainbow8 Rainbow16 BlackWhite Contours each of these four items describes one of the possible four SibGraf Map representations Map of 8 colors Map of 16 colors Map of 8 gray shades and Contour Map Grid Legend Show hide discretization mesh and legend for Color Map Redraw Redraw current plot Zoom Out Turn off zoom can also be done with ESC key Annotate See Help on Annotate below in Section Annotate on page 28 Help Index Open a window with the help index About Displays SibGraf info MICROTEC 3 02 User s Manual 27 MicroTec Graphics SibGraf Chapter 3 Map Set Contours Set Contours subitem under the View menu item of the SibGraf Map opens the window where the user can assign the levels at which the contour lines are draw
22. D OEB1 6 11e 6 cm2 s The OED for Boron 111 orientation AD OEPO 1 44105 cm2 s The OED for Phosphorous 100 orientation AD OEP1 56510 cm2 s The OED for Phosphorous 111 orientation Ex OEE 2 08 eV The activation energy for OED OELDY 25 0 um The vertical coordinate exponent for OED OELDX 2 0 um The lateral coordinate exponent for OED Br OEBOX 0 3 none The oxidation rate exponent for OED Deal Grove oxidation kinetic constants dU _ dt B JURA B P B OX Oo Ez exp 72 2 B OR PR exp Poy Pox DROX Dry oxidation kinetic constants Symbol Name Default Units Description B BD 0 214 um2 s_ Parabolic oxidation rate constant in dry O R BAD 1730 um2 s Linear oxidation rate constant in dry O ES BDE 1 23 eV Parabolic activation energy in dry O 48 MICROTEC 3 02 User s Manual Chapter 4 Process Simulation Symbol Name Default Units Description Es BADE 2 0 eV Linear oxidation activation energy in dry O B BPF 0 75 none Exponent of the effective pressure WEOX Wet oxidation kinetic constants Symbol Name Default Units Description OR ORO 0 595 none Orientation coefficient for 100 OR ORI 1 0 none Orientation coefficient for 111 T TCP 950 0 Le Parabolic constant critical temperature for wet O B BWI 4 722 um s Parabolic oxidation rate co
23. EGR Segregation parameters A description of the SiDif directives follows 4 7 SiDif basic directives MESH computational domain and mesh parameters Name Default Units Description NX 30 none Number of mesh nodes in X direction along the surface It must be greater than 3 NY 30 none Number of mesh nodes in Y direction into the depth of the domain It must be greater than 3 A greater number of mesh nodes gives a higher computational accuracy at the expense of a larger CPU time XX 1 um Domain size in X direction microns The domain should cover a region near edges of all the masks where the two dimensionality takes place YY 1 um Domain size in Y direction microns The domain should be deep enough to cover the maximum expected depth of the implanted or deposited dopant penetration IM 1 none This key must be 1 for a uniform mesh If it is zero or nega tive the mesh will be exponentially condensed in the origin of coordinates MICROTEC 3 02 User s Manual 41 Process Simulation Chapter 4 Name Default Units Description AX 0 none Logarithm of the ratio of two adjacent mesh step sizes in the X direction if the mesh is not uniform AY 0 none Analogous parameter for the Y direction Parameters AX AY may be omitted if IM 1 Nonuniform mesh is preferable for a simulation including relatively fine structures near the surface COMM Comm
24. H C De Graaf Measurements of bandgap narrowing in silicon bipolar transistor Solid State Electronics vol 19 pp 857 862 1976 A G Chynoweth Ionization rates for electrons and holes in silicon Phys Rev vol 109 pp 1537 1540 1958 D M Caughey and R E Thomas Carrier mobilities in silicon semi empirically related to temperature doping and injection level Proc IEEE vol 55 pp 2192 2193 1967 K Yamaguchi A mobility model for carriers in the MOS inversion layer IEEE Trans Electron Devices vol 30 pp 658 663 1983 10 C Lombardi S Manzini A Saporito and M Vanzi A physically based mobility model for numerical simulation of nonplanar devices IEEE Trans Computer Aided Design vol 7 pp 1164 1170 November 1988 11 D L Scharfetter H K Gummel Numerical simulation of Read diode oscillator IEEE Trans Electron Devices vol 16 pp 64 70 1969 12 M S Obrecht A modification of ICCG method for solving discretized continuity equations for semiconductor device at any voltages Submitted to Solid State Electronics 13 H A Van Der Vorst Bi CGSTAB a fast and smoothly converging variant of Bi CG for the solution of nonsymmetric linear systems SIAM Journ Sci Stat Comput vol 13 pp 631 644 March 1992 14 H K Gummel A self consistent iterative scheme for one dimensional steady state transis tor calculations IEEE Trans Elec
25. Micro Tec Software Package for Two Dimensional Process and Device Simulation Version 3 02 for Windows User s Manual Siborg Systems Inc Copyright 1994 95 96 97 98 by Siborg Systems Inc All Rights Reserved First Printing January 1998 Photocopying or any other reproduction of any part of this document violates copyright law Additional copies of this document are available from the publisher Siborg Systems Inc 24 Combermere Cres Waterloo Ontario N2L 5B1 CANADA Phone 519 888 9906 FAX 519 725 9522 E mail microtecOsiborg ca Web http www siborg ca Trademarks MicroTec SiDif ES MergIC SemSim and SibGraf Mare trademarks of Siborg Systems Inc Microsoft MS DOS are registered trademark of Microsoft Corporation IBM is a registered trademark of International Business Machines Corporation CONTENTS 1 Getting Started 7 1 1 Introduction 9 1 2 Installing MicroTec 10 1 3 Quick start 10 2 MicroTec User Interface 13 2 1 Introduction 15 2 2 Running MicroTec 15 3 MicroTec Graphics SibGraf 19 3 1 Introduction 21 3 2 SibGraf 2D Output 21 File 21 Curve 22 View 23 Annotate 23 Help 23 2D Status Bar 23 2D Tool Bar 23 2D Data File Structure 24 3 3 SibGraf 3D Output 24 File 24 Surface 25 View 25 Annotate 25 Help 25 3D Status Bar 25 3D Tool Bar 26 3 4 SibGraf Map Menu 26 File 26 Surface 27 View 27 Help 27 Map Set Contours 28 Map Status Bar 28 Map Tool Bar 28 3 5 Annotate 2
26. NUM 1 none Electrode number Important when setting initial voltages and voltage step in IV data LOC 1 none Location of the electrode 1 is on the top and 2 is on the bot tom of the domain XLT 0 um Left electrode edge coordinate XRT 1 um Right electrode edge coordinate TOX 0 02 um Gate oxide thickness XQS 0 01 um Location of the Gaussian Qss under the gate AQS 0 01 um Exponent of the Gaussian Qss under the gate QSH 0 em Homogeneous component of the Qss under the gate QSG 0 cm Gaussian component of the Qss under the gate VSN 11015 cm s Electron recombination velocity under the gate VSP 11015 cm s Hole recombination velocity under the gate FIM 4 25 eV Work function of the gate metal 72 MICROTEC 3 02 User s Manual Chapter 6 Device Simulation Parameters Xos Ao s Qsp Osa define slow surface states or fixed surface charge at the Si S102 interface as follows Oss Os oseo E 2 SCHO Schottky electrode Name Default Units Description NAME schottky none Electrode name The first letter will be used for current and voltage subscripts NUM 1 none Electrode number Important when setting initial voltages and voltage step in IV data LOC 1 none Location of the electrode 1 is on the top and 2 is on the bot tom of the domain XLT 0 um Left electrode edge coordinate XRT 1 um Right electrode edge coordinate VSN 1 10 cm s Electron recombinat
27. Ni 4 ni Ny 2 6 20 MICROTEC 3 02 User s Manual 63 Device Simulation Chapter 6 Wo To Vi 6 21 q ie where Ny Np N is the net doping concentration and V is the k th contact voltage On the surface of Schottky contacts BiSim only carrier concentrations are defined by the follow ing relations Jav QV sn 0 gt 6 22 Fo y QVsp P Peg gt 6 23 Wo Pg Vz 6 24 where D is the difference of the intrinsic semiconductor and metal workfunctions v denotes cur rent density component normal to the interface and equilibrium concentrations n q Peg are qy Neg neexp 2e 6 25 av Peg nexo E 6 26 On insulating segments of the boundary for current densities we have Fay UR O surg 6 27 Ty RO surg 6 28 For normal components of electric field according to the Gauss theorem we have at the interface eE y amp F yt Oss 6 29 where are dielectric permittivities of the respective materials and Q is a fixed surface charge density For open segments of the boundary E equals zero For boundary segments underneath gate contacts the electric field is approximated by the formula 64 MICROTEC 3 02 User s Manual Chapter 6 Device Simulation Ve uv Ey Mae Vo 6 30 gt hy where Va ej Vo appi Pg ha is the oxide thickness and y is the local potential value at the interface Mobility Models Several options for concentration an
28. O 1E16 AS 1E12 OR 111 ASIM XM 10 EN 300 DZ 1E15 ANNE TC 1000 TM 3600 TA 600 OX 0 EPIT TH 2 PH 1 E12 BO 1 E12 AS 1 E15 TC 1200 TM 600 TA 150 BOIM XM 1 DZ 1 E12 EN 100 ANNE TC 1000 TM 3600 TA 600 OX 0 Emitter region To simulate emitter formation in the large fragment simulated in the previous example only its small upper region is considered The substrate is doped by arsenic at 1015 cm with boron implanted at 100 KeV and 10 ions cm and arsenic implanted at 60 KeV and 101 ions cm through the mask into the left half of the region The wafer is then annealed for 1 hour at 1000 C The mesh is nonuniform in order to resolve a steep initial arsenic profile near the surface MESH NX 15 NY 20 XX 1 Y Y 1 1 IM 0 AX 1 E 5 AY 1 COMM Emitter region SUBS PH 1E12 BO 1E12 AS 1E15 OR 111 BOIM XM 2 DZ 1 E12 EN 100 ASIM XM 0 5 DZ 1 E15 EN 60 ANNE TC 1000 TM 3600 TA 600 OX 0 MICROTEC 3 02 User s Manual 53 Process Simulation Chapter 4 54 MICROTEC 3 02 User s Manual DEVICE FORMATION MICROTEC 3 02 User s Manual 53 Chapter 5 Device formation 5 1 Introduction MergIC provides an interface between the process simulation tool SiDif and the device simula tion tool SemSim MergIC merges device fragments simulated by SiDif into a device domain to be used in the device simulation The fragments may be placed arbitrarily in the device domain symmetrized and replicated The output file of MergIC s
29. and Y cross sections for ward and backward This can also be done by using the arrow keys on the keyboard The button Log Z is used to switch to logarithmic scale and back The last three buttons are used to open SibGraf Map window with the same data and SibGraf 2D windows with the current X and Y cross sections or to add one more curve to the existing X or Y window 3 4 SibGraf Map Menu The user has five menu choices File Surface View Annotate and Help The subtopics avail able under these menus are described below SibGraf Map File Surface View Annotate Help Electron concentration cm 3 2 9 9977e 19 grid 30 x 30 File Open Open a file containing a plot previously created and saved by this program Load Load data from a file containing 2D distribution data 26 MICROTEC 3 02 User s Manual Chapter 3 MicroTec Graphics SibGraf Save Save the plot to the picture file that is currently open If there is no plot that is currently open if the Load function was used instead then this function will behave as the Save As func tion described below Save As Save the plot to a picture file A window will be provided to allow you to choose the file name Clear Erase the plot that is currently in the plot window Print Print the plot that is currently in the plot window to a printer or to a Postscript file New Window Open a new Sibgraf Map window Exit
30. ay be plot ted View Options Opens a window where the user can assign labels for horizontal and vertical axes and the title for the plot The user can also specify the lowest value for the logarithm function corre sponding to the argument approaching zero Tool bar Status bar If checked the items will be shown in the window If you would like to increase the plotting area you may want to uncheck them See the description below in this sec tion Redraw Redraw current surface Zoom Out Turns off zoom can also be done with ESC key Annotate See Help on Annotate below in Section Annotate on page 28 Help Index Open a window with the help index About Display SibGraf info 3D Status Bar The status bar is the strip at the bottom of the plot window The first line of three numbers in the MICROTEC 3 02 User s Manual 25 MicroTec Graphics SibGraf Chapter 3 status bar shows the values of the X and Y coordinates for the corresponding current cross sec tions and the Z value at the point of their intersection The bottom line shows the mesh step num bers of current X and Y cross sections and the overall dimension of the grid 3D Tool Bar The tool bar is the line of buttons just below the main menu and above the plot window The first four buttons are used to rotate the surface about horizontal and vertical axes associated with the screen The next four buttons are used to move the current X
31. c Has 399 1 v E NBsarn Barr u N E E T N E ni i r sat n Symbol Name Default Units Description B BN 475 107 cm s Fitting parameter for perpendicular electric filed Es CON 1 74 10 gt Fitting parameter for perpendicular electric filed and doping concentration 9 CPON 0 125 none Exponent of the doping concentration parameter Ho UON 52 2 em2 Vs Minimum hole mobility Umax UMAN 1 42 10 em2 Vs Maximum hole mobility y ULN 43 4 cm V s Concentration correction term C CRN 0 681016 em Critical doping concentration C CSN 3431022 em Critical doping concentration in the correction term MICROTEC 3 02 User s Manual 77 Device Simulation Chapter 6 Symbol Name Default Units Description P PCN 0 0 cm s Concentration correction of the minimum mobility a ALPN 0 68 none Exponent in the concentration factor B BETN 2 0 none Exponent in the concentration correction factor Y GAMN 2 5 none Temperature factor exponent DELN 5 82 10 4 V s Acoustic term parameter A BESN 2 0 none Exponent in the saturation velocity e VSAN 1 07 107 cm s Saturation velocity Analogous parameters for holes note that expression for u in this case is different 1 V T poexp P N Pmax Hi Ey r Symbol Name Default Units Description B BP 9 9
32. ce Open a window which shows the data source for the current curve Line Color Marker Change the corresponding attribute of the current curve 22 MICROTEC 3 02 User s Manual Chapter 3 MicroTec Graphics SibGraf View Options Open a window where the user can assign labels for horizontal and vertical axes and the title for the plot The user can also specify the lowest value for the logarithm function correspond ing to the argument approaching zero The user can choose to show only markers or only lines for all curves in the current plot Information in this window may be saved by pressing Save button File setup mt will be created and the settings will be read in every time a new SibGraf 2D win dow is opened Grid Legend Switch grid and legend on and off Zoom Out Turn off zoom can also be done with ESC key Annotate See general description of Annotate command in Section Annotate on page 28 Help Index Help index for SibGraf About Display SibGraf info 2D Status Bar The status bar is the strip at the bottom of the plot window It shows the value of the X and Y coor dinates for the current marker on the current curve The current marker is shown in red color 2D Tool Bar The tool bar is the line of buttons just below the main menu and above the plot window The first two buttons are used to change the current curve which is shown in yellow color Each click will change the current cur
33. ce simulators are available mostly for UNIX based workstations Normally they require tens of Mbytes of memory even for modest size meshes Increasing performance and wide spread availability of IBM PCs and compatibles encourage the development of software tools that can be used for 2D modeling of semiconductor devices and processes with a rather low memory capacity and speed of computation Recently a few efficient programs were developed for two dimensional semiconductor process device simulation on a PC which have now been integrated together into a package named MicroTec MicroTec The Semiconductor TCAD Calculator MicroTec allows 2D silicon process modeling including implantation diffusion and oxidation and 2D steady state semiconductor device simulation like MOSFET DMOS JFET BJT IGBT Schottky photosensitive devices etc Although MicroTec is significantly simplified compared to widely available commercial simulators it nevertheless is a very powerful modeling tool for industrial semiconductor process device design In many instances MicroTec outperforms exist ing commercial tools and it is remarkably robust and easy to use MicroTec is especially attractive for educational purposes due to its ease of use and robustness It enables development of a set of problems for a tutorial in semiconductor device physics with min imal effort The goal of such a computer aided course would be to give students basic ideas about modern semiconductor
34. d field dependent mobility models are available For bipolar devices the concentration and field dependent mobility is taken in a form similar to 8 O _ id 1 i n 300 a E Hs nM ED Gunga Hn CE E 30 Gal Gy Fe 300 Weg y a Hs pEnpn Pr U N Ep E Us nN Ep 1 2 6 32 Vsat n And analogous expression for holes For MOS devices either the Yamaguchi expression 9 or the recent expression by Lombardi et al 10 may be used In the first case 9 TS TEARS e 2 up VN E E N E 1 c 6 33 ad ep oe ES vs Ve 1 1 N 2 L N E bol 1 1 alEI 6 34 Net where E and E are corresponding longitudinal and transverse components of the electric field with respect to the current direction In the second case 10 the mobility includes three terms MICROTEC 3 02 User s Manual 65 Device Simulation Chapter 6 6 35 where u is the carrier mobility limited by the surface acoustic phonon scattering y is the carrier mobility in the bulk silicon and u is the carrier mobility limited by the surface roughness scattering These terms are described by the following formulae IN la ML E T B 6 36 by t E Wile L N T Hot Hmax n Ron Bi 6 37 NY C8 Eau os ey h Less _ 6 where Mmax T Umax 300 and We The basic parameters in the above expressions are user defined 6 3 Numerical techniqu
35. dels for MOS LSI fabrication processes IEEE Trans Electr Dev v ED 28 p 574 1981 R B Fair and J C Tsai Theory and measurement of boron segregation in SiO during oxi dation J Electrochem Soc vol 125 p 2050 1978 V I Koldyaev V A Moroz et al Two dimensional simulation of the doping and oxidation of silicon Optoelectronics Instrumentation and Data Processing Avtometria No 3 p 50 1988 A S Grove et al Redistribution of acceptor and donor impurities under oxidation of sili con J Applied Physics vol 35 p 2695 1964 H Runge Distribution of implanted ions under arbitrarily shaped mask Phys Stat Sol v 39 a p 595 1977 G Schneider M Zedan A modified strongly implicit procedure for the numerical solution of field problem Numerical Heat Transfer vol 4 p 1 1981 H A Van Der Vorst Bi CGSTAB a fast and smoothly converging variant of Bi CG for the solution of nonsymmetric linear systems SIAM Journ Sci Stat Comput vol 13 pp 631 644 March 1992 S Furukawa H Matsumura and H Ishiwara Theoretical Considerations on Lateral Spread of Implanted Ions Jap J Apll Phys vol 11 No 2 pp 134 142 1972 L N Lie R R Razouk and B E Deal High Pressure Oxidation of Silicon in Dry Oxygen J Electrochem Soc vol 129 No 12 pp 2828 2834 1982 R R Razouk L N Lie and B E Deal Kinetics of High Pressure Oxidation of Silicon in Pyrog
36. dif ference was 0 02 0 03 microns Thus the important parameter p n junction depth is determined with an accuracy sufficiently high 2 for an I V curve evaluation 4 4 References 1 M S Obrecht A L Alexandrov SIDIF a program for two dimensional modelling of diffu sion and oxidation Solid State Electronics Software Survey Section v 34 No 8 1991 2 A L Alexandrov M S Obrecht G V Gadiyak Efficient finite difference method for numer ical modelling of thermal redistribution of interacting impurities under oxidizing ambient Solid State Electronics v 35 p 1549 1552 1992 3 Process and Device Simulation for MOS VLSI Circuits Ed by P Antognetti R W Dutton et al Martinus Nijhoff Publishers 1983 4 R W Dutton and D A Antoniadis Models for computer simulation of complete IC fabrica 38 MICROTEC 3 02 User s Manual Chapter 4 Process Simulation 10 11 12 13 14 15 16 17 tion processes IEEE Trans Electr Dev v ED 26 p 490 1979 C D Maldonado ROMANS II A two dimensional process simulator Appl Phys vol A31 p 119 1983 R W Dutton C P Ho et al VLSI process modelling SUPREM III IEEE Trans Electr Dev v ED 30 p 1439 1983 B E Deal and A S Grove General relationship for the thermal oxidation of silicon J Applied Physics vol 36 p 3770 1965 K Tanigushi et al Two dimensional computer simulation mo
37. e A finite difference technique on a rectangular grid is used together with a decoupled method of iterating over the non linearity the so called Gummel iteration For discretization of the continuity equations we use the conventional Scharfetter Gummel approximation 11 Conjugate gradient methods with preconditioning 12 13 are available for solving the linear systems 6 4 References 1 M S Obrecht SIMOS two dimensional steady state simulator for MOS devices Solid State Electronics Software Survey Section vol 32 No 6 1989 2 M S Obrecht and J M G Teven BISIM a program for steady state two dimensional modeling of various bipolar devices Solid State Electronics Software Survey Section vol 34 No 7 1991 3 M S Obrecht A new stable method for linearization of discretized basic semiconductor equations Solid State Electronics vol 36 No 4 pp 643 648 1993 4 M S Obrecht and M I Elmasry Speeding up of convergence of Gummel iterations for 66 MICROTEC 3 02 User s Manual Chapter 6 Device Simulation transient simulation Proceedings of the Ninth International Conference on the Numerical Analysis of Semiconductor Devices and Integrated Circuits Copper Mountains CO April 6 8 1993 Front Range Press pp 20 21 M S Obrecht and M I Elmasry Speeding up of convergence of Gummel iterations for transient simulation COMPEL v 12 pp 311 317 J V Slotboom and
38. e and Help The subtopics avail able under these menus are described below SibGraf 3D 1 LEP le EJ os ef Electron c on c o des s 9977e 19 fa DO x7 ax ooo HY grid 30x30 File Open Open a picture file previously created and saved by this program Load Load data from a file containing 2D distribution data By default the files should have extension 3d Save Save the plot to the picture file that is currently open If there is no picture file that is cur rently open if the Load function was used instead then this function will behave as the Save As function described below Save As Save the plot to a picture file A window will be provided to allow you to choose the 24 MICROTEC 3 02 User s Manual Chapter 3 MicroTec Graphics SibGraf picture file name Clear Erase the plot that is currently in the plot window Print Print the plot that is currently in the plot window to a printer or to a Postscript file New Window Opens new Sibgraf 3D window Exit Close the SibGraf 3D window Surface Source Opens a window which shows the data source for the current surface If the current plot was invoked through the Open function Source is the only subitem under Surface If the file with 2D distribution data was loaded through the Load function all the sur faces contained in that file are listed after the Source item Any of these surfaces m
39. e IV data and even correspond to transconductance data The table contains names as well as maximum and minimum values of each column in the current family The first two check boxes beside each column allow the user to choose which column will be the X axis and which will be the Y axis The third check box allows the user to choose a column which will be multiplied by the column chosen as the Y axis In this case a product of the respective elements of the two columns will be plotted The fourth check box allows the user to choose a column which will be used as a divider for the Y axis In this case a ratio of the respective elements of the two columns will be plotted e g current gain B I Tp The user can type the name of the curve being created into the box called Curve Name If no curve name is specified it is the same as the name of the curve given as the column chosen as the Y axis When all required information is selected at least the X and Y axes must be given the curve may be added to the plot by pressing the Add button The data used to create a curve may be viewed later by selecting the Source item from the Curve menu Copy Copy the current curve from the plot to the Sibgraf clipboard A very useful feature to create different windows with different sets of curves in each of them Paste Add the curve from the Sibgraf clipboard to the current plot Delete Delete the current yellow curve from the plot Sour
40. enic Steam J Electrochem Soc vol 128 No 10 pp 2214 2220 1981 4 5 Running SiDif To run SiDif from the MicroTec shell select a SiDif project in the project list on the Select Project page and click Run in the main MicroTec menu You may also Add Update Copy and or Delete projects in the main menu MICROTEC 3 02 User s Manual 39 Process Simulation Chapter 4 If you want to modify a project click on Copy button new project will be created with the old project name and copy at the end After that you may change the project settings by click ing on the Project Settings page tag This will display directives in the input file Double click on a directive unfolds it and lets you edit the parameters If you want to start a new project type the project name in the Name window select SiDif in the Method window and click Add A new project will be created with default parameter set tings On the output SiDif generates a doping data file which may be directly used in the device simu lation This output file also may be used by MergIC to produce a more complex final device structure by copying overlaying and symmetrizing fragments simulated by SiDif Black 3D Output button means that the result has been successfully computed and you may plot the output doping profiles by clicking on this button If it is grey click Run button to per form proces
41. eration has been reached GRES 0 01 kT q Gummel residual criterion for closure Iteration stops when either the Gummel residual or the maximum number of Gum mel iteration has been reached MODE Model options Name Default Units Description ELHL 0 none Solve continuity equations for both carriers if ELHL 0 Solve for electrons or holes only if ELHL is equal 1 or 2 respec tively HVDO 1 none Use Slotboom heavy doping bandgap narrowing model if HVDO 1 and otherwise if HVDO 0 IMPI 0 none Use Chinoweth impact ionization model if IMPI 1 and other wise if IMPI 0 DOP Analytical doping data This directive may include any number of DOPA subdirectives The analytical doping profiles are described by a superposition of wells For each well is defined by one DOPA subdirective according to the following formula 70 MICROTEC 3 02 User s Manual Chapter 6 Device Simulation Ne ie ner A Ve fa a z The concentration in every well is a constant equal to N in the rectangle Xief Ytop Xright Y bottom and decreases as a Gaussian beyond the rectangle N is the maximum concentration in the well it is positive for donors and negative for acceptors DOPA Doping well Name Default Units Description COMM Comm none Doping well name DOP 1 1018 cm Maximum concentration in the doping well XLFT 0 um Left edge of the doping we
42. erves as the numerical doping input file for SemSim MergIC allows one to significantly reduce the fragment size used in the process simulation and hence the CPU time This also significantly simplifies mesh generation for the process simulation 5 2 Running MergIC To run MergIC from the MicroTec shell e Select a project corresponding to MerglC or add a new project by selecting MergIC method in the Method window MergIC requires the main input file with the extension INP and one doping data file for every fragment used in the device structure These fragment doping files must be previously generated by SiDif e Edit parameters by switching to Project Settings page of the in the main MicroTec menu e Click Run button To run SemSim outside the MicroTec shell the command line should look as follows mergic lt project gt inp Refer to sections below for the description of the input file On the output MergIC generates a doping data file which is used in a device simulation by SemSim If you want to plot the output doping file click 3D Output in the main MicroTec menu after running MergIC Note Since the device simulation tool SemSim in the present version of MicroTec does not handle non planar structures a planarization of the doping profiles is made in MergIC Therefore vertical doping profiles generated by SiDif are shifted vertically so as to align the Si SiO interface with the line y O At the same time the impuri
43. eters 69 SOLV Computation control 70 MODE Model options 70 DOP Analytical doping data 70 DOPA Doping well 71 DOPN Numerical doping data 71 ELE Electrode directive 71 OHMI Ohmic electrode 72 GATE Gate electrode 72 SCHO Schottky electrode 73 FIVD IV data directive 73 IVDA IV Curve 73 iv MICROTEC 3 02 User s Manual CONTENTS MAT Material properties 74 BAND Temperature and bandgap parameters 74 PERM Dielectric permittivity 75 WORK Semiconductor work function 75 MOB Mobility models 75 CONM Constant mobility model 75 YAMA Yamaguchi mobility model 76 LOMB Lombardi surface mobility model 77 BIPO Bipolar mobility model 79 REC Recombination parameters 80 SRH Shockley Read Hall recombination parameters 80 AUGE Auger recombination parameters 82 SURF Surface recombination parameters 82 RADI Radiative recombination parameters 82 IMP Impact Ionization 82 IONE Impact ionization exponent 83 IONP Impact ionization coefficient 84 PHO Photogeneration 84 PHOT Photogeneration well 84 MICROTEC 3 02 User s Manual v Chapter vi MICROTEC 3 02 User s Manual GETTING STARTED MICROTEC 3 02 User s Manual 7 Chapter 1 Getting Started 1 1 Introduction Semiconductor device modeling has become a standard design tool in the microelectronics indus try A few years ago this modeling was performed primarily on supercomputers At the present time a number of commercial 2D process and devi
44. f each segment by clicking with the left mouse button in the plot area The click of the right mouse button will terminate the line drawing To modify exist ing Annotate Line object first select it by clicking the left mouse button at the line Then either the whole line or any of its nodes can be moved to the desired position with the left mouse button Click with the left mouse button anywhere away from the line will terminate the modification mode When the subitem Text is chosen a window will appear where the user can type the required text and chose whether the border around the text is shown When the OK button is pressed the text will be placed in the centre of the plot area To move the existing Annotate Text object first select it by clicking the left mouse button inside the text region Then the text region can be moved to the desired position by dragging it with the left mouse button If the content of the text object is to be changed the user should chose subitem Edit under Annotate in the main menu A click of the left mouse button anywhere away from the text region will terminate the modification mode The user can delete an annotate line or text by selecting it as the current annotate object as described above and then choosing subitem Delete under Annotate in the main menu 3 6 Zooming The user may zoom in on a particular rectangle of any plot 2D 3D or Map as follows Position the cursor over a point on the plot that you would
45. fault Units Description TC 1000 je Temperature of oxidation centigrade TM 2000 S Time of oxidation in seconds TAU 1 S Initial time step in seconds The recommended value is 30 s for a temperature of 1200 C 100 s for 1100 C 200 s for 1000 C and 500 s for 900 C and lower For an accurate eval uation on a fine mesh the recommended value is 2 10 times lower than the one above Use a smaller TAU if the number of nonlinear iterations exceeds 7 PH 1 0 10 2 em Initial uniform phosphorus concentration BO 1 0 10 2 cm The same parameter for boron doping AS 1 0 10 2 cm The same parameter for arsenic doping TH 1 um Thickness of the grown epitaxial layer Existing profile of dopants is shifted by TH towards the depth of the domain and the dopant thermal redistribution during epitaxy is evaluated Make sure that YY is large enough not to lose the buried layer COMM Comm none Comment line 4 8 SiDif model parameter directives BAND Bandgap and intrinsic carrier concentration MICROTEC 3 02 User s Manual 45 Process Simulation Chapter 4 E n noT exp 59 2kT Symbol Name Default Units Description Nio CINT 3 873 10 6 em Pre exponential constant for intrinsic concentration E EINT 1 5 none Temperature exponent for intrinsic concentration Ec EGAP 0 60474 eV Bandgap width for intrinsic concentration DIFF Diffusivity of Arsenic Boron and Pho
46. fficient in Delta for bird s beak Yo GAMO 0 83 um The first coefficient in Gamma for bird s beak vi GAMI 4 5e 4 um The second coefficient in Gamma for bird s beak Y GAM2 0 039 um The third coefficient in Gamma for bird s beak Y GAM3 0 76 um The forth coefficient in Gamma for bird s beak Y4 GAM4 3 5e 4 um The fifth coefficient in Gamma for bird s beak Ys GAMS 0 03 um The sixth coefficient in Gamma for bird s beak 50 MICROTEC 3 02 User s Manual Chapter 4 Process Simulation SEGR Segregation parameters 1 Vox Eso J C 1 m A 2n A OX il an Vox seg exp kT EXP kT Symbol Name Default Units Description As e SEGA 1 01022 none The Segregation coefficient for Arsenic Ass SEGP 1 01022 none The Segregation coefficient for Phosphorous A g SGBD 13 4 none The Segregation coefficient for Boron in dry O Es SBDE 0 33 eV The Segregation activation energy in dry O A SBWO 65 2 none The Segregation coefficient for Boron in wet O seg for orientation 100 A SBWI 104 none The Segregation coefficient for Boron in wet O for orientation 111 Eas SBWE 0 66 eV The Segregation activation energy in wet O Ay ALAM 125104 um s Pre factor in critical oxidation rate in segregation for Boron E ELAM 2 0 eV Activation energy in critical oxidation rate in seg regation for Boron 4 9 Examples of SiDif
47. he Update button To mod ify directives parameters switch to the Parameter Settings page as described above If you need to start a new project type a name of the project in the Name window select method in the Method window and click the Add button A project with default directive parameter settings will be created Change current page to Project Settings and edit parameters as described above To run a simulation click the Run button After the simulation is complete you may display the results by clicking on 2D Output or 3D Output button for plotting I V curves or 3D contour plots of two dimensional distributions respectively Click on Curve or Surface for 2D Out put or 3D Output respetively to plot an IV curve or a surface 2D distributions available for plotting are electrostatic potential carrier and current densities Fermi quasi potentials electric field components etc You may also plot 2D cross sections and IV plots as well as transconductances as a function of applied voltage For more information on Graphics Tools refer to Chapter 3 below 12 MICROTEC 3 02 User s Manual MICROTEC USER INTERFACE MICROTEC 3 02 User s Manual 13 Chapter 2 MicroTec User Interface 2 1 Introduction MicroTec is a shell integrating four programs for silicon process device simulation e SiDif two dimensional SImulator for DIFfusion and oxidation e
48. he Disk into this directory Change your current directory to C MICROTEC type pkunzip mt302 zip and press lt Enter gt DO De 7 Ifyou have a multiple copy MicroTec floppy installation disk repeat steps 1 6 on other com puters Note When installing the floppy disk must be open for writing 1 3 Quick start Select a project in the project list window on the Select Project page by clicking the left mouse button at the project name The corresponding simulator name will be shown in the Method window The simulator name may be SiDif MergIC SemSim or Batch for the process simula tion generation of the device structure device simulation or a batch mode simulation respectively In the batch mode you may run a batch of jobs using different tools for example to run a process simulation a generation of the final device structure using MergIC and then a device simulation for the generated device with a number of different IV curves 10 MICROTEC 3 02 User s Manual Chapter 1 Getting Started MICROTEC 3 0 HI Cn Pros EE e e Select Project Project Settings Tes LOCOS process LOCOS oxidation simulation Batch test 2 Drain Gate formation new Method Drain Gate formation test LOCOS process LOCOS process test MerglC Schottky diode 2D implantation diffusion oxidation as una cr p o Select Project To modify project settings click on Project Settings tab Anot
49. he entire structure of a semiconductor device for subsequent evaluation of I V curves in a few minutes on a PC The algorithm 2 is based on the finite difference formulation and a rectangular mesh The phys ical model adopted describes the diffusion process for up to three interacting charged impurities in a two dimensional domain with moving oxide boundary and impurity segregation at the Si SiO interface In the case of implantation the initial profiles of each impurity are approximated by the conventional Runge s model 12 The program is written in FORTRAN 77 and can be used on IBM AT 386 or higher with an EGA VGA SVGA adapter running under Windows Dynamic memory allocation is used in SiDif with 400 Kbytes required for a 2500 node mesh Typical process simulation requires about a minute on Pentium 100 4 2 Physical model Diffusion of charged impurities is influenced by the presence of an internal electric field The physical model for diffusivities which accounts for the influence of charged defects is taken from 4 5 J D NC qZ MC E 4 1 where C is the concentration of the k th impurity D is the diffusivity Z is the charge number H is the electrical mobility q is the elementary charge and E is the electric field This model uses the quasineutral approximation which relates the electric field to impurity concentrations Esivwe Lv m 2 4 2 ac 1 n ac Exc 4 3 MICROTEC 3 02 User s Manual 33
50. her page of the main MicroTec window will appear showing a list of directives subdirectives and parameters Click on a folder symbol to open it Double click a parameter to edit it MICROTEC 3 0 EE Select Project Project Settings 2 LOCOS process P0000010 3D E Domain and Mesh E Numerical Solution E Substrate E Boron implant E Oxidation E Arsenic implant Annealing Selec Project If you click a directive subdirective parameter by the left and then the right mouse button a new window pops up allowing you to Delete Copy Insert or Add a new entry If you select Insert or Add a list of available directives subdirectives parameters pops up Select an item an click Okay Detailed description of the directives may be found in chapters describing every simulator below MICROTEC 3 02 User s Manual 11 Getting Started Chapter 1 MICROTEC 3 0 Select Project Project Settings E LOCOS process P0000010 3D E Domain and Mesh E Numerical Solution Delete E Substrate Boron implant Insert Directive E Oxidation Add Subdirective E Arsenic implant Add Parameter E Annealing teres process Boron implant Jj The most convenient way of starting a new project is to select a proper existing project and then to click the Copy button A new project will be created with copy at the name end in the Name window Edit the name in the Name window and click t
51. icantly reducing the memory requirements Surprisingly these methods appear to be more efficient than the Newton method in a number of instances and certainly are numerically more stable than the latter SemSim as well as its predecessors SIMOS 1 and BiSim 2 is based on the Gummel like decoupled technique and require only 4 Kbyte of memory for a 10 000 node mesh A finite difference technique on a rectangular grid is employed For discretization of the continuity equations the conventional Scharfetter Gummel approximation 11 is used Conjugate gradient methods with preconditioning 12 13 are used for solving the linear systems 6 2 Basic System of Equations The basic equations comprise of the Poisson equation standard notation is used and the continuity equations for electrons and holes Vy L n p Np N 6 1 eE Lo R 6 6 2 q one R G 6 3 q P where J J p are related to the carrier densities and the electrostatic potential J qnu V V qD Vn 6 4 J 4PU V Y X qD Vr 6 5 6 6 MICROTEC 3 02 User s Manual 61 Device Simulation Chapter 6 Bandgap narrowing The additional term x in the drift components of 4 5 is due to the band gap narrowing effects and is treated accordingly to the Slotboom model 6 1 1 os Xo mn Gata L 6 7 where N Np N4 Temperature dependence of the bandgap is as follows E T E 0 E aT 6 8 g T E p Intrinsic carrier conce
52. ion retarded diffusion 8 Oxidation changes the diffusivity because it generates interstitials in the crystalline lattice In SiDif the Taniguchi model 1s used 8 Box E OX dU O Ax 2 D D AD E y exp IT Sep x oz 4 10 The diffusivity enhancement decays exponentially in the above formula where Ax is the distance from the mask edge Ax 0 outside the masked region and y is the vertical distance from the interface 8 Analytical oxidation model For the analytical oxidation model the Deal Grove formulation is used 7 in SiDif dU __B dt 2U A 4 11 where U is the oxide thickness and A B are kinetic constants which are proportional to the pres sure and depend on the ambient composition The values A B are significantly higher if the ambi ent contains water vapor or HCI In the latter case the constants are given by 16 17 E B Ep B P 8 exp a OR P R exp 4 12 Here P x is the pressure of the oxidizing ambient in atmospheres and P eff is the effective pres MICROTEC 3 02 User s Manual 35 Process Simulation Chapter 4 sure for the linear kinetic coefficient 2 In the case of wet oxidation P P P and in the case of dry oxidation P eff pl The factor OR depends on the silicon orientation 17 If there is an initial oxide film with a thickness of U on the surface of the semiconductor then 4 11 leads to U t varf ar 4 4 13 Usually only a fragment of the wafer s
53. ion velocity at the interface VSP 1 105 cm s Hole recombination velocity at the interface FIB 0 eV Potential barrier the difference between the Fermi potential of the contact material and that of the intrinsic semiconductor IVD IV data directive This directive may include any number of IVDA subdirectives Each IVDA subdirective defines one IV curve for which one the contact voltages is ramped IVDA IV Curve Name Default Units Description TEXT none Text to be output to the IV data file NUMC 1 none Number of the contact to sweep the voltage NPNT 1 none Number of IV points to be evaluated MICROTEC 3 02 User s Manual 73 Device Simulation Chapter 6 Name Default Units Description VSTE 0 1 V Voltage step size VI 0 V Initial voltage for contact 1 V2 0 V Initial voltage for contact 2 V3 V20 0 V Same as above just a repetition Initial voltage for a contact 3 20 Maximum contact number is equal to 20 MAT Material properties This directive contains three unique subdirectives BAND PERM and WORK BAND Temperature and bandgap parameters AE X g Vo BGN in N J n N No BGN N E T E 300 2 300 T 300 E T E NAT neo NAM neo E 300 300 Symbol Name Default Units Description T TEMP 300 K Temperature E 300 EG30 1 08 eV Bandgap width
54. izing ambient to create a LOCOS structure MESH NX 25 NY 35 XX 2 Y Y 2 IM 1 COMM LOCOS SUBS PH 1E12 BO 1E15 AS 1E12 OR 111 ASIM XM 1 EN 200 DZ 1E15 BOIM XM 1 EN 100 DZ 1 E13 ANNE TC 1100 TM 3600 TA 100 0X 2 XO 1 PO 0 9 Doping by deposition The substrate is initially doped with phosphorus at 101 cm Then boron is deposited on the whole surface with a surface concentration of 10 8 cm for 30 minutes at 1000 C After this arsenic is deposited through the mask on the left side of the region with a surface concentration of 1020 cm for 30 minutes at 1100 C MESH NX 35 NY 35 XX 2 Y Y 2 5 IM 1 COMM Deposition example SUBS PH 1E12 BO 1E13 AS 1E12 OR 111 BODE XD 3 CS 1 E18 ANNE TC 1000 TM 1800 TA 200 OX 0 ASDE XD 1 CS 1E20 ANNE TC 1100 TM 1800 TA 100 OX 0 Buried layer and epitaxy 3 A substrate is doped by boron at 101 cm arsenic is implanted in the whole region at 300 KeV and 101 jons cm and annealed at 1000 C for 1 hour in an inert ambient Epitaxy follows for 52 MICROTEC 3 02 User s Manual Chapter 4 Process Simulation 10 minutes at 1200 C resulting in a layer thickness of 2 microns which 1s doped by arsenic at 105 cm Then boron is implanted at 100 KeV and 10 2 ions cm into the left side of the region and annealed at 1000 C for 60 minutes A nonuniform mesh is used MESH NX 25 NY 38 XX 2 Y Y 3 5 IM 0 AX 1 E 5 AY 1 COMM Buried layer example SUBS PH 1E12 B
55. like to use as the corner of a new plot Press and hold the left mouse button as you move the mouse which will show a rectangle on the plot corre sponding to the area that will be shown on a new plot When you have a rectangle defined that covers the area of the plot that you would like to zoom in on release the mouse button and the plot will be replaced by a plot of the selected area To restore the original plot you may press the ESC key or select Zoom Out from the View menu In SibGraf 2D and Map windows you may unzoom the plot by selecting a rectangle outside the plotting area using the left mouse button MICROTEC 3 02 User s Manual 29 MicroTec Graphics SibGraf Chapter 3 30 MICROTEC 3 02 User s Manual PROCESS SIMULATION MICROTEC 3 02 User s Manual 31 Chapter 4 Process Simulation 4 1 Introduction It is well known that analytical approximations for doping profiles typically do not adequately reflect results of fabrication processing especially for devices with submicron dimensions A program named SiDif has been developed 1 to compute two dimensional impurity profiles of VLSI elements that have undergone various fabrication steps The fabrication process may include processing steps such as ion implantation or surface deposition arsenic boron or phos phorous with subsequent annealing under oxidizing or inert ambient Resulting doping profiles may be used in a straightforward manner to generate t
56. ll XRGT 1 um Right edge of the doping well YTOP 0 um Top of the doping well YBOT 1 um Bottom of the doping well ALX 0 05 um Characteristic length in X direction ALY 0 07 um Characteristic length in Y direction DOPN Numerical doping data The only parameter in this directive is the doping data file name In this case the doping data file should contain doping data generated by SiDif or post processed by MergIC which in turn uses output files generated by the process simulator SiDif Name Default Units Description FILE none Name of the file where data previously evaluated using SiDif or MergIC are stored ELE Electrode directive MICROTEC 3 02 User s Manual 71 Device Simulation Chapter 6 OHMI Ohmic electrode Name Default Units Description NAME ohmic none Electrode name The first letter will be used for current and voltage subscripts NUM 1 none Electrode number Important when setting initial voltages and voltage step in IV data LOC 1 none Location of the electrode 1 is on the top and 2 is on the bot tom of the domain XLT 0 um Left electrode edge coordinate XRT 1 um Right electrode edge coordinate GATE Gate electrode Name Default Units Description NAME gate none Electrode name The first letter will be used for current and voltage subscripts
57. llel electric field REC Recombination parameters This directive contains four unique subdirectives SRH AUGE SURF and RADI SRH Shockley Read Hall recombination parameters 80 MICROTEC 3 02 User s Manual Chapter 6 Device Simulation R G ory oo Mi SRH n nj exp E kT t p njeexp E kT t ee Tao N N OSRH n i Asen nt Bores es Corn a on gt n Te po P Oe N N SRH p SRH SRH SRH j NSRH p fo N srH p Symbol Name Default Units Description Es ETRA 0 0 eV Energy level of SRH trap relatively to the intrinsic Fermi level T0 TAUN 1 0107 s Life time for electrons Nsru n NSRN 5 010 cm Concentration parameter SRH n ANSR 1 0 none parameter BSRH n BNSR 1 0 none parameter CSRH n CNSR 0 0 none parameter ASRH n EN 2 0 none parameter T0 TAUP 1 0107 s Life time for holes Nsru p NSRP 5 010 cm Concentration parameter SRH p APSR 1 0 none parameter Bor Hp BPSR 1 0 none parameter CSRH p CPSR 0 0 none parameter OSRH p EP 2 0 none parameter MICROTEC 3 02 User s Manual 81 Device Simulation Chapter 6 AUGE Auger recombination parameters 2 R G Auger np MAC Aug n F Caug pP Symbol Name Default Units Description Caro AUGN 2 8 107 cm s Auger recombination coefficient Ci AUGP 9 9 1072 cm s Auger recombination coefficient SURF Surface
58. me Default Units Description NX 30 none Number of mesh nodes in X direction along the wafer sur face It must be greater than 3 A greater number of mesh nodes gives a higher computational accuracy at the expense of a larger CPU time NY 30 none Number of mesh nodes in Y direction into the depth of the wafer It must be greater than 3 XX 1 um Domain size in X direction microns YY 1 um Domain size in Y direction ZZ 1 um Domain size in Z direction in other words device width HYO 0 01 um Y direction first step size used only if IMESH is equal to 0 MICROTEC 3 02 User s Manual 69 Device Simulation Chapter 6 Name Default Units Description MESH 2 none If MESH 0 the mesh size is constant in X direction and expo nentially growing in Y direction If MESH 1 mesh data are to be read from file If MESH 2 automatic remeshing is per formed in both X and Y directions If MESH 3 or 4 remesh ing is done only for X or Y directions respectively SOLV Computation control Name Default Units Description COMM Comm none Comment line to be written in the output file BATC 1 none If BATC 1 simulate without interactive plotting after every IV point if BATC 0 otherwise GUMM 100 none Number of Gummel iterations for closure Iteration stops when either the Gummel residual or the maximum number of Gummel it
59. n for the current surface Automatic the user can assign the start and the step values for Z or Log Z and choose whether all or none of the contour labels are shown Manual the user can add a new contour line by pressing the Add button and specifying Z or Log Z values for it remove existing contour line by choosing it in the table and pressing the but ton Remove or modify the existing contour lines by changing its Z or Log Z value The check box in front of each level value indicates whether the contour labels for all contours at this level are shown or not The user can also modify the existing contour line and its label by positioning the mouse on a par ticular label on the plot and pressing the right mouse button A menu will appear through which the user can choose to remove from the plot either this label or all contour lines at the correspond ing level The location of a label can be changed by dragging the label with the left mouse button If by this operation the label is moved completely out of the plot area it becomes invisible although it still exists and will appear if for example the Unzoom function is used Map Status Bar The status bar is the strip at the bottom of the plot window If the probe mode is off the first line of three numbers in the status bar shows the values of the X and Y coordinates for the corresponding current sections and the Z value at the point of their intersection If the probe mode
60. nded symmetrically to the right and SY 1 means symmetrization over the left edge or extension to the left DX um Length of the fragment extension or a piece fitted between the symmetrical regions It must be larger than 0 It is ignored if SY 0 This region is filled with the doping profile from the fragment borders which face each other 56 MICROTEC 3 02 User s Manual Chapter 5 Device formation Name Default Units Description OV 1 none Extension of the doping profile of the fragment to the whole device domain It is needed to create the basic structure for example the initial doping implantation to the whole device domain or buried layer If OV 1 the doping values on the bot tom edge of the fragment are continued to the bottom of the device domain and then the profiles on the right and left edges of the fitted fragment are extended uniformly to the right and left borders of the device domain respectively If OV 0 the fragment is placed over the region replacing the doping which was there before No extension to the right left or down is made in this case OV 1 option is preferable for the first frag ment IF Name of the SiDif output file with the doping data for the fragment It must be separated by lt 5 4 Examples of MergIC input file Examples of MergIC input files follow The last three examples differ only in the way the fragments are placed
61. nstant in wet O for T lt T Es BWEl 1 17 ev Parabolic activation energy in wet O for T lt Te B BW2 0 1167 um s Parabolic oxidation rate constant in wet O for T gt T Es BWE2 0 78 eV Parabolic activation energy in wet O for T gt Te T TCL 900 0 Le Linear constant critical temperature for wet O R BAWI 575 0 um s Linear oxidation rate constant in wet O for T lt T Ep BAWEI 1 6 eV Linear oxidation activation energy in wet O for T lt T R BAW2 4 917 10 um s Linear oxidation rate constant in wet O for T gt T Ep BAWE2 2 05 eV Linear oxidation activation energy in wet O for T gt Te LOCO Local oxidation bird s beak formula parameters U x t U U t Ug A 2 Y MICROTEC 3 02 User s Manual 49 Process Simulation Chapter 4 _ 89 87 8 gt M U IE 83 04 7 65 U t Lee T1 UO Symbol Name Default Units Description x KHIO 0 0 um The Kappa for 100 orientation for bird s beak x KHII 1 0 um The Kappa for 111 orientation for bird s beak DELO 0 97 um The first coefficient in Delta for bird s beak 5 DEL1 6 0e 4 um The second coefficient in Delta for bird s beak 5 DEL2 0 034 um The third coefficient in Delta for bird s beak 5 DEL3 0 49 um The forth coefficient in Delta for bird s beak 54 DEL4 2 le 4 um The fifth coefficient in Delta for bird s beak 5 DELS 0 03 um The sixth coe
62. nt _ If you select Delete the current entry will be deleted If you select Copy a new entry with a copy of the current entry content will be added at the end of the project tree If you select Insert or Add a new window pops up showing you a list of entries available to add at this stage Select one of them and click Okay Parameters that are added have default values To change this value double click the parameter and a new window will pop up showing you the parameter current value and a brief parameter description Edit the parameter value in the text box and click Okay There are different types of directives in MicroTec unique non unique and mandatory optional For example IV curve subdirective is optional and non unique that is one may skip this subdi rective or may use it a number of times to generate a family of IV curves On contrary the Basic directive is mandatory and unique Any new created project will have all mandatory directives in it with the default values of parameters Mandatory directives cannot be deleted Method Text Box When you start a new project you may select appropriate Method in the Method Text Box The following four options are available e SiDif two dimensional SImulation of implantation diffusion and oxidation e MergIC program for MERGing fragments of simulated by SiDif e SemSim two dimensional steady state semiconductor device simulation e
63. ntration is n T NoN exp 5 6 9 Effective density of states 3 2 NAT Nc 300 6 10 3 2 NAT Ny 300 lt 2 6 11 SRH and Auger Recombination and Impact Ionization The Shockley Read Hall recombination Auger recombination and avalanche generation are taken into account R G R G spy R Gauger Gay gt 6 12 2 np n ee oh 6 13 n Nie Tp p Nie Tn R G srH 62 MICROTEC 3 02 User s Manual Chapter 6 Device Simulation R G auger np nj C n C p 5 6 14 using concentration dependent lifetimes T p li gt e 6 15 as Nn ref Nn ref and an analogous expression for holes Impact ionization is modeled using the Chynoweth model 7 Gay Old Opl 6 16 where bal pl N 17 a a er al and Q a exp T Ji 6 17 Surface Recombination Surface recombination takes place at the interfaces semiconductor oxide or at the surface of non ideal for example polysilicon or Schottky contacts The recombination rate is described by the formula 2 np n 6 18 n Nnie Vsp nie Von e R G surf where v Vip are recombination velocities for electrons and holes Boundary Conditions A few types of boundary conditions are available in SemSim At ideal Ohmic contacts the follow ing conditions are imposed assuming infinite recombination rate for electrons and holes no Ny 4 ni Ny 2 6 19 Po
64. ons in E Eo EPO 0 0 V cm Electric field range for holes E EP1 6 07 105 V cm Electric field range for holes E EP2 6 07 105 V cm Electric field range for holes pt BPO 0 0 V cm Field exponent for holes in 0 Ey pi BP1 2 09 10 V cm Field exponent for holes in Ep E Le BP2 1 4 10 V cm Field exponent for holes in E Ey he BP3 1 4106 V cm Field exponent for holes in E ae ANO 0 0 l cm Ioniz coef for elect in range 0 Ep MICROTEC 3 02 User s Manual 83 Device Simulation Chapter 6 IONP Impact ionization coefficient Symbol Name Default Units Description e ANO 0 0 l cm Ioniz coef for elect in range 0 Ep pa ANI 7 0 10 gt l cm Ioniz coef for elect in range Eq Ej a AN2 7 010 l cm Ioniz coef for elect in range E E gt a AN3 7 0 10 gt l cm Ioniz coef for elect in range E TA APO 0 0 l cm Ioniz coef for holes in range O Ep TA API 1 3106 l cm Ioniz coef for holes in range Eq Ej do AP2 4 4 10 l cm Ioniz coef for holes in range Ej E gt a AP3 4 4 10 l cm Ioniz coef for holes in range E infinity PHO Photogeneration This directive may include any number of PHOT subdirectives The photogeneration distribu tion is described by a superposition of photogeneration wells Each well is defined by one PHOT subdirective similar to the analytical doping profile using subdirective DOPA
65. owed by and should be ended by Each subdirective contains parameters separated by spaces or commas They start 6 with the subdirective key followed by and ended by Input is closed by all directives after are ignored Directive subdirective tree looks as follows BAS Basic directives MESH Mesh and domain parameters SOLV Numerical solution parameters MODE Physical models F DOP Analytical doping data DOPA Doping well DOPN Numerical doping data from file HELE Electrodes OHMI Ohmic electrode GATE Gate electrode SCHO Schottky electrode e IVD IV data or a set of IV curves eIVDA IV curve e MAT Material Properties BAND Temperature and bandgap PERM Dielectric permittivity eWORK Workfunction 68 MICROTEC 3 02 User s Manual Chapter 6 Device Simulation e MOB Mobility models CONM Constant mobility YAMA Yamaguchi mobility LOMB Lombardi mobility BIPO Bipolar mobility F REC Recombination parameters eSRH Shockley Read Hall recombination parameters AUGE Auger recombination parameters eSURF Surface recombination RADI Radiative recombination e IMP Impact ionization I ONE Impact ionization exponents eIONP Impact ionization coefficients PHO Photogeneration PHOT Photogeneration well BAS Basic directives This directive includes the following three unique directives MESH SOLV and MODE MESH Domain and mesh parameters Na
66. recombination parameters 2 np nis R G a gt ee surf 1 Nig Ysp D Mie Von Symbol Name Default Units Description v VSRN 1 1071 cm s Surface recombination velocity for sn 0 electrons v VSRP 10710 cm s Surface recombination velocity for sp 1 10 electrons RADI Radiative recombination parameters 2 R G q B np n gt Symbol Name Default Units Description RATE 110714 cm s Radiative recombination coefficient IMP Impact Ionization This directive contains two unique subdirectives IONE and IONP 82 MICROTEC 3 02 User s Manual Chapter 6 Device Simulation IONE Impact ionization exponent DJ V gt a anexo TEF a apero TEET av Gay Apn 0 1 For four ranges of electric field 0 E Ej E E E gt E infinity piecewise coefficients Ay Ay Bos b are defined below Symbol Name Default Units Description Eo ENO 0 0 V cm Electric field range 0 Eg for electrons E ENI 4 010 V cm Electric field range Eg E for electrons E gt EN2 6 0 10 gt V cm Electric field range E E for electrons bo BNO 0 0 V cm Field exponent for electrons in 0 Ep bl BN1 1 4106 V cm Field exponent for electrons in E E4 p BN2 1 4106 V cm Field exponent for electrons in E Ey b BN3 1 4106 V cm Field exponent for electr
67. rity caused by oxide motion is included 2 The total impurity dose within the semiconductor and oxide is conserved to the extent of the floating point accuracy of the computer For the solution of several coupled diffusion equations the finite difference equations of each impurity are solved sequentially with initial values of impurity concentrations taken from the previous iteration or previous time step Iterations continue until the solution for all impurities converges to a given accuracy The incomplete factorization method 13 combined with the con jugate gradient method 14 are employed to solve the equations of the 5 diagonal matrix The algorithm was tested by comparing results with examples published in papers 3 5 6 10 The following example of LOCOS process simulation demonstrates CPU time requirements 2 014 The boron is implanted with 100 KeV energy and a 1 ions cm dose and the arsenic is implanted with 100 KeV and a 101 ions cm dose An annealing step at 1000 C in a wet ambi ent follows for 30 minutes Ten minutes of CPU time were required for this example using a mesh of 45x45 nodes on a 25 MHz PC 386 The same CPU time on a 12 MHz PC AT 286 was required for the simulation with a mesh of 25x25 and twice as large time step The difference in position of the contour lines for both calculations was less than 0 01 microns in the region of the p n junction In the regions with concentration values of 1014101 cm the
68. s simulation and after the result has been computed the button becomes black 4 6 SiDif input file SiDif main input file contains directives and parameters Each directive starts a group of parame ters separated by spaces or commas and ended by The computational domain and the mesh are the same for all the processing steps The last step must be ended by All directives after will be ignored Note Only one step with the oxidizing annealing is allowed in the present version of SiDif Only implantation deposition and inert annealing may be simulated after the oxide formation All the directives are of two types basic directives and model parameter directives SiDif basic directives MESH computational domain and mesh parameters SUBS substrate parameters SOLV numerical solution control PHDE phosphorus deposition BODE boron deposition ASDE arsenic deposition PHIM phosphorus implant BOIM boron implant eASIM arsenic implant OXID oxidation parameters 40 MICROTEC 3 02 User s Manual Chapter 4 Process Simulation eANNE annealing parameters EPTT epi layer formation SiDif model parameter directives BAND Bandgap and intrinsic carrier concentration DIFF Diffusivity of Arsenic Boron and Phosphorus OED Oxidation enhanced diffusion DROX Dry oxidation kinetic constants WEOX Wet oxidation kinetic constants LOCO Local oxidation bird s beak formula parameters S
69. sphorus E 1 pu Pas kT A1 B Dp Doexp D AS Da exp Symbol Name Default Units Description Dox DX0A 22 9 cm2 s The pre exponential constant for Arsenic Eok DXEA 4 1 eV The activation energy for Arsenic B BETA 100 none The charged vacancy effectiveness for Arsenic Dox DX0B 0 555 cm2 s The pre exponential constant for Boron Eok DXEB 3 42 eV The activation energy for Boron B BETB 3 0 none The charged vacancy effectiveness for Boron Do DXOP 3 85 cm2 s The pre exponential constant for Phosphorous Ep DXEP 3 66 eV The activation energy for Phosphorous D DMP 4 4 cm2 s The pre exponential constant for Phosphorous E DMEP 4 0 eV The activation energy for Phosphorous 46 MICROTEC 3 02 User s Manual Chapter 4 Process Simulation Symbol Name Default Units Description D DMMP 44 2 cm2 s The pre exponential constant for Phosphorous E DMMEP 4 37 eV The activation energy for Phosphorous MICROTEC 3 02 User s Manual 47 Process Simulation Chapter 4 OED Oxidation enhanced diffusion Box E ox dU O Ax 2 D D AD E exp ET exp SS i Jo Symbol Name Default Units Description AD OEAO 0 0 cm2 s The OED for Arsenic 100 orientation AD OEA1 0 0 cm2 s The OED for Arsenic 111 orientation AD OEBO 1 66105 cm2 s The OED for Boron 100 orientation A
70. the interface to not reach equilibrium values In this case a correction was proposed 10 1 Y York Jox c1 m 4 20 a m A Vo where is the kinetic constant of the segregation reaction Equilibrium values of m were taken from 9 Ion implantation Ion implantation is widely used now as a standard tool for the doping of semiconductor wafers In SiDif an analytic ion implantation model is employed In a one dimensional case the implant is described by a Gaussian distribution 1 y R I y exp fate 4 21 2 210 26 where R and are the projected range and vertical standard deviation respectively and y is the distance from the top of the wafer material The two dimensional implant profile is described by the formula 15 el IQ X X E XX IG y 5 e er 4 22 where x and x are the coordinates of the left and the right edges of the grid cell To obtain the MICROTEC 3 02 User s Manual 37 Process Simulation Chapter 4 final implant distribution expression 4 22 is integrated over the exposed surface of the wafer 4 3 Simulation algorithm The finite difference technique 2 was chosen for the diffusion equation discretization due to a property of the matrix equation to be solved symmetrical 5 diagonal matrix with diagonal domi nance For each mesh node the difference mass balance equation is written For nodes adjacent to an oxide boundary the segregation flux of an impu
71. tron Devices vol 11 pp 455 465 1964 15 A De Mari An accurate numerical steady state one dimensional solution of the p n junc tion Solid St Electronics vol 11 p 33 58 1968 16 M S Mock A time dependent numerical model of the insulated gate field effect transis tor Solid State Electronics vol 24 pp 959 966 1981 6 5 Running SemSim To run SemSim from the MicroTec shell Select a project corresponding to SemSim or add a new project by selecting SemSim method in the Method window Edit parameters by switching to Project Settings page of the in the main MicroTec menu Click Run button MICROTEC 3 02 User s Manual 67 Device Simulation Chapter 6 To run SemSim outside the MicroTec the command line should look as follows semsim lt project gt inp File inst pas must be present in the directory where MicroTec is installed There are two output files generated by SemSim 1 A file with two dimensional distributions It has the extension 3D 2 A file with I V data It has the extension 2D These two files may be displayed by MicroTec graphics tools Click on the 2D or 3D button in the MicroTec main menu to plot the results Refer to sections below for the description of the input file 6 6 SemSim input file SemSim main input file contains directives subdirectives and parameters Each directive con tains subdirectives or parameters starts with the directive key foll
72. ty concentration values at y locations beyond the original domain generated by SiDif are filled with the value of the last point available i e the bottom impurity concentration value in the SiDif output file 5 3 MergIC input file e Each directive starts a group of parameters separated by spaces or commas and ended by e Each FRAG directive must be ended by The last directive must be ended by MICROTEC 3 02 User s Manual 55 Device formation Chapter 5 e All directives after will be ignored MESH Domain and mesh Name Default Units Description NX Number of nodes in X direction along the surface it must be greater than 3 NY Number of nodes in Y direction into the depth of the domain It must be greater than 3 The number of nodes affects accuracy and disk space required for the output file XX Device size in X direction um YY Device size in Y direction um COMM Comm none Comment line FRAG fragment description Name Default Units Description X0 0 um X coordinate of the upper left corner of fragment in the device domain um It can exceed the overall length of the device 1f you want to invert the fragment over the vertical symmetry axis SY none Type of the fragment symmetrization If SY 0 there is no fragment symmetrization SY 1 means symmetrization over its right edge that is the fragment is exte
73. urface is exposed to the oxidizing ambient while the rest of the surface is covered by a nitride mask In this case oxidation in the area near the mask edge is described by the bird s beak formula U t U xm U x t Uot Perf 4 14 with the following empirical parameters 10 8 3 T 8 In Uy i 1 3 5 85 8 7 8 7 U t 4 15 _ Y YT y ln Up 1 3 YA T 14I U 1 4 16 where x 1 and 0 for 111 and 100 orientation respectively Segregation The oxidation of silicon is accompanied by the segregation in other words a jump in the impu rity concentration at the moving S1 SiO interface The segregation causes an impurity flux density at the interface which may be written as 1 Joy a i rs 4 17 Ss where C is the impurity concentration in Si at the SiO boundary m is the segregation coefficient v is the oxide growth rate in the direction normal to the interface and is the ratio of volumes of Si and SiO that is equal to 0 44 36 MICROTEC 3 02 User s Manual Chapter 4 Process Simulation For boron EE E m A seg XP us AS A exp 4 18 For phosphorous and arsenic the segregation coefficient is large about 100 and usually close to the equilibrium value 11 so that the impurity may be considered to be completely pushed into the silicon In this case Jox Cpy 4 19 OX At high oxidation rates the segregation may cause concentrations at both sides of
74. ve to the next one The first button cycles upward through the curves and the second cycles downward This can also be done by using the up and down arrow keys on the keyboard The next two buttons change the current point marker on the current curve The current marker is shown in red color The buttons move the point to the left and right respectively This can also be done using the left and right arrow keys on the keyboard The two buttons Log X and Log Y are used to switch to logarithmic scale and back on the X and Y axis respectively The last button marked Del deletes the current curve from the plot MICROTEC 3 02 User s Manual 23 MicroTec Graphics SibGraf Chapter 3 2D Data File Structure This section describes the format of a data file that can be loaded by the Load selection under the File menu By default the program looks for files with an extension of 2d where is any character Each data file contains sets of data which are referred to as families Each family is a number of data columns each with the same number of entries rows After the file is loaded the user may choose which column is the X axis and which column or columns will be shown on the Y axis The user may also choose to plot a product or ratio of any two columns on the Y axis It allows to plot such quantities as current gain B I Ip etc 3 3 SibGraf 3D Output The user has five menu choices File Surface View Annotat

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