FIB Operating Procedure - Nebraska Center for Materials and
Contents
1. NCMN Nebraska Center for Materials and Nanoscience University of Nebraska FIB Operating Procedure Effective Date 08 14 2012 Author s Jiong Hua Phone 402 472 3773 Email jhua2 unl edu 1 Introduction 11 Key Words Focused Ion Beam FIB FEI Strata 201 Ion milling 1 2 Purpose This document provides instructions for operating the FEI Strata 201 workstation Use of this tool requires the understanding of the fundamentals of ion milling SEM and nanopatterning 1 3 Applicability 1 3 1 Locations The tool is located at Clean room of nanoscience research center 1 3 2 Restrictions and Limitations 1 4 e Never put in sticky things All samples should have been cleaned properly in appropriate solvents before being put into the sample holder e Never put anything that can outgas under high vacuum The chamber vacuum is below 1 0x10 mBar e Good electrical contact is necessary to avoid charging of sample Charging effect makes it impossible to get good images or patterns Restrictions on Working Alone Normal working hours are from 8am to 6pm M F Working alone is permitted with completion of an orientation to this written procedure and hands on training from the specialist The user must reserve the time through online calendar in advance Any samples left inside the chamber by the previous user will be taken out without notification Assistance from the specialist is available during w2. Optimizing the Image Change Scan speed and beam current refer to Step 6 Low beam current and slow scan produce better image In general the highest resolution at lowest scan rate gives the best image You can also improve image quality by using Averaging in top menu Scan Correct focus with the knob on MUI keyboard Focusing at 2x to 3x the magnification needed for the final result make the lower magnification image sharper For example for images at magnification 2000x you need to correct focus at magnification 4000x to 8000x Correct astigmatism with the knob on MUI keyboard The sharpest image can be obtained with high resolution single slow scan by selecting Scan gt Set Single Scan and choosing the scan rate in the dialog box 10 Milling Selecting suitable beam current for your purpose Normally higher than 70pA and a typical milling time should between several seconds and 20 minutes Move the stage close to the interested area Focus and stigmate the beam in the area adjacent to the pattern Move to the area for milling and grab an image with single slow scan refer to Step 8 Select a pattern tool and draw the patterns Choose a material file in the patterning box on work page Normally we use Si mtr file for most milling work The relative depth for different materials can be calculated based on corresponding milling yields Put suitable depth for each pattern System will calculate the
3. References e xP FIB User Manual 6 User Access Level Normal User Requires specialist to be present Expert User Does not require specialist to be present
4. total milling time Click Start button in the top toolbar to begin milling You may stop milling at anytime by click Stop button or press Escape on the keyboard Wait until milling procedure finishes 11 Depositing Pt Contact specialist for details 12 Cross sectioning Contact specialist for details 13 Data Transfering The system support floppy disk or CD R USB flash drivers are also applicable Contact specialist for details 14 Turn off Procedures e Turn off High Voltage Click on HV button in startup page Wait until the voltage drops down to Zero and the button turns grey e Turn off Source Click on SOURCE button Wait until the button turns grey N e Check the stage position on the work page if they show different values Lower or level the stage if necessary to ensure the stage won t hit the door or any components inside the chamber iG BS WEEE HSS ISVS WHER IOSAMIRIOSESERIBICS Click VENT button to vent the chamber and remove load your sample refer to Step 3 e Close the chamber door and click PUMP button Wait until Vac OK e Turn off the power of each attached instrument 5 in total 15 Clean up all samples pens and notebooks from the area End End of Procedure 4 Post Performance 4 1 Recordkeeping 4 2 Feedback Report any unusual or problematic behavior of the setup by contacting the specialist 5 References 5 1 Technical
5. d Click Start Scanning button in the top toolbar to begin imaging An image displays possibly out of focus and with incorrect contrast and brightness setting Correct the contrast and brightness with the knobs on MUI board Correct the focus with the knobs on MUI board Using joy stick to move the stage and locate the sample Click Freeze Scanning button in the top toolbar to stop live imaging Eucentric Change the beam current to 70pA and click Start Scanning button to obtain live imaging Adjust contrast brightness and focus if necessary Display the small cross in the center of the screen by press Shift F5 if it is not shown up Set magnification at 1000x find a distinct feature such as a particle or corner of a bond pad and center it under the cross by moving stage or double click the feature with mouse Click Stage gt Zero Beam Shift in the top menu Watching the feature change stage tile to 1 by setting T to 1 in work page Use the knob Z control to bring the feature back under the cross Change the tilt to 0 and move the stage to center the feature again Refocus the image if necessary Repeat the above procedure for 5 10 and 40 Check the eucentric by tilting the stage from 40 to 0 and verifying that the feature stays in the center of the screen If the feature shifts significantly repeat the above steps or contact specialist for help
6. orking hours only If an error occurs during off hours record the error in the Logfile and send an email to the specialist Tool will be checked in the following work day User will be notified when sample left in chamber is available for pickup Problems with equipment malfunctions breakage etc should be reported to the specialist and recorded in the tool Logfile iio For any emergency involving injuries fire chemical spills etc call 911 2 Preparations Receive this procedure from the specialist 3 Execution Step by step work breakdown Step Alerts Action 1 A Operating Software XP 2 25 from FED Checking status of the system before starting Vacuum Vac OK appears in the status area Column vacuum should be lower than 2x107 mbar The ion column SOURCE and HV should be off the buttons are gray Beam BLANK is on the button is yellow Loading samples Always wear Powder free gloves when load unload samples Check the stage position on the work page if they show different values Lower or level the stage if necessary to ensure the stage won t hit the door or any components inside the chamber Click VENT on the startup page Wait 5 minutes until the chamber is vented the chamber door will open slightly Open the chamber door gently and load wafer sample If there is a sample stub on the stage use the 1 5 mm hex Allen wrench to loose the
7. screw in the sample stage Lift the sample stub up and remove it Put the prepared sample stub on the stage and gently tight the screw Check the level of the sample holder is low enough to avoid hitting on the components inside the chamber Use the knob Z control beside the chamber door to adjust the height of stage if necessary Check it with the height checking stand Gently close the chamber door and Click PUMP on the startup page Hold the door until the rough pump works smoothly Wait 15 minutes Vac OK will appear in the status area when evacuation is completed Turning on Source and High Voltage aperture selection Turn on Source mbar click SOURCE ON The system will turn on the source and measure V I slope Wait until all the measurement finish Apply High Voltage After the source is turned on click HV ON to apply high voltage Wait until HV reaches 30KV Log file Entries Fill out the log file with the corresponding parameters Finding the Sample and Obtaining an Image Verify the Source and HV are on the buttons show yellow Set proper imaging Current Select Beam gt click on the proper beam current normally less than 11pA in the top menu Set scan rate Click Scan gt Set Continuous Scan in the top menu to display the Set Continuous Scan dialog box Choose a high resolution fast scan rate Set lowest magnification by using the knob on MUI boar
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