AFM1 Imaging Operation Procedure (Tapping Mode or Contact Mode)

Transcription

1 AFM1 Imaging Operation Procedure (Tapping Mode or Contact Mode) 1. Log into the Log Usage system on the SMIF web site 2. Open Nanoscope 6.14r1 software by double clicking on the Nanoscope 6.14r1 desktop icon 3. Select the desired mode of operation by choosing the appropriate workspace in the File/Open Workspace menu. The workspaces are found in the directory D:V614r1/Workspaces. The following workspaces are good starting points and can be used for most samples: Tapping Mode: smif_default_tapping_d.wks Contact Mode: smif_default_contact_d.wks 4. Click on Scan in the Workspace window to connect the software to the instrument 5. Mount the appropriate AFM tip into the cantilever holder. Be sure that the tip is in contact with the back end and left side of the groove per the following picture. TESP Tip properly positioned in cantilever holder prior to clamping TESP Tip properly positioned in cantilever holder after clamping You may use your own AFM tip, or purchase one of the following from SMIF: Tapping Mode: TESP silicon probe Contact Mode: ORC8-10 silicon nitride probe 6. Mount the cantilever holder onto the end of the scanner head a. Tighten the set screw to unclamp the scanner head from the dove tail and remove the scanner head from the cradle. Be sure not to pull on the cables that connect the scanner head to the electronics box b. Mount the cantilever holder by gently fitting it onto the pins at the end of the scanner head. DO NOT use excessive force as this may damage the scanner head c. Replace the scanner head in the cradle and loosen the set screw to clamp the head assembly in the dove tail 7. Align the laser a. Turn the illumination off by entering a 0 in the Illumination box of the Other controls menu in the Scan ParmList window. b. Place the blank side of a business card face up on the granite stage so that the laser is visible on the card c. Open the Meter window by clicking on Meter in the Workspace window Page 1 of 6 Revision 7

2 d. Using the two knobs at the top of the scanner head, follow the diagram below to adjust the laser position so that the laser is visually aligned with is the tip of the cantilever on the AFM tip. 1. Move the laser in the x direction to find AFM tip edge. Then move slightly back from the edge. 2. Move the laser in the y direction to find the cantilever. 3. Move the laser in the x direction to the right to find the cantilever edge. Now make fine adjustments to the x and y laser position knobs to maximize the signal sum in the meter window as shown below Red dot centered for detector alignment Signal sum maximized for laser alignment e. Remove the business card from the granite stage 8. Align the photodetector a. Use the two knobs on the left side of the scanner head to adjust the photodetector position 1. Coarse adjustment: Center the position of the red dot in the window on the scanner head 2. Fine adjustment: Center the position of the red dot in the cross-hairs of the meter display screen as shown above Tapping Mode: Set the Vertical Deflection to 0.0 volts ( 0.5V) Contact Mode: Set the Vertical Deflection to about 2.0 Volts b. Close the Meter window Page 2 of 6 Revision 7

3 9. Load sample a. Place sample on stage b. Select Navigate window and move the Z-position up using the Z-motor up arrow button in the Navigate window. (This is a precaution to prevent the sample from hitting the head assembly) c. Increase illumination from zero to 100 d. Move the sample under the probe using the X-Y stage movement arrows in the Navigate window. 10. Locate and focus on tip a. Click on Locate Tip in the Navigate window b. Zoom all the way out by clicking on Zoom Out c. Center the tip of the cantilever under the cross hairs using the two adjustment knobs located to the left of the optical objective on the microscope d. Focus on the tip end of the cantilever using the Optics arrows keys in the Navigate window e. Click on Zoom in to zoom all the way in or use the up arrow to zoom partially in on the tip and re-focus and re-center the tip if necessary. f. Click OK (The software will automatically change to the focus on sample surface menu) 11. Focus on the sample surface a. Zoom out to the maximum position to get the largest field of view possible b. Use the Z-motor down arrow button in the Navigate window to visually close the gap between the sample and the scanner head to about 2-3mm. c. Now look at image on screen and keep adjusting the Z-motor position until the sample surface is in focus. If the sample is smooth and has no surface features to focus on, then change the Focus On setting to Tip Reflection and adjust the Z-position until the reflection of the AFM tip is in focus. Page 3 of 6 Revision 7

4 d. Move to the desired measurement area of the sample under the cross hairs using the X-Y arrow keys in the Navigate window e. Zoom in on the area of interest and fine focus using the Z-position if necessary 12. Tune Cantilever (Tapping Mode AFM only) a. Click on the Tuning Fork Icon b. Set the Start and End frequency to bracket the resonant frequency value given on the box that the cantilever probe came from. (Typically 0kHz 500kHz for TESP silicon probes) c. Set the target amplitude to 2 volts d. Set the peak offset to 5% e. Click on Auto Tune button f. Note: If the tool does not auto tune properly and the probe tip is in good condition, try resetting the controller communication connection by selecting Tools/Reset Controller and then repeating the auto tune. g. When completed, click the Exit button 13. Set Initial Scan Parameters a. In the Scan Controls panel, enter the following settings: 1. Scan Size: Set to desired measurement area (< 70 m) 2. Aspect Ratio 1:1 3. X and Y offsets: 0 4. Scan angle: 0 5. Scan rate: Tapping mode: 1 Hz Contact mode: 2 Hz 6. Samples/line: 256, 512, or Lines: 256, 512, or Slow scan enabled 9. XY closed loop Lower setting: Lower resolution, faster speed Higher setting: Higher resolution, slower speed Off for scan size of < 1 m On for scan size of > 1 m b. For Tapping Mode AFM, in the Feedback Controls Panel, enter the following settings: 1. Integral Gain: Proportional Gain: Leave other settings alone c. For Contact Mode AFM, in the Feedback Controls Panel, enter the following settings: 1. Setpoint: 0 volts (2 volts difference from value set in Step 8) 2. Integral Gain: Proportional Gain: Close the instrument cover 15. Click on the Engage Icon Engage Withdraw Page 4 of 6 Revision 7

5 16. Optimize Scan Parameters a. Tapping Mode AFM 1. If the line in the Z-Center position moves far to the extended end (indicator turns red), the tip has false engaged. Disengage the probe tip and execute the engage command again 2. Check to see if Trace and Retrace are tracking each other well. If they are tracking, the lines should look the same, but they will not necessarily exactly overlap each other. 3. If they are not tracking well, adjust the Setpoint and/or Gains, to improve the tracking (See training notebook pages 36-41). It is often easier to disable the slow scan axis while making adjustments, so that the scanned feature stays in the field of view. Typical adjustments are as follows: Lower the setpoint to improve tracking between the trace and re-trace Lower the gains to reduce the noise b. Contact Mode AFM 1. Once engaged increase the Setpoint by using the right arrow key and observe the Z-Center Position. If the line in the Z-Center position moves far to the extended end (indicator turns red), the tip has false engaged. Disengage the probe tip, increase the setpoint by +2 volts and execute the engage command again. If the Z-Center position does not change greatly, you are on the sample surface and can go to the next step. 2. Check to see if Trace and Retrace are tracking each other well. If they are tracking, the lines should look the same, but they will not necessarily exactly overlap each other. 3. If they are not tracking well, adjust the Setpoint, Gains, and/or Scan Rate to improve the tracking (See training notebook pages and 36-41). It is often easier to disable the slow scan axis while making adjustments, so that the scanned feature stays in the field of view. 4. Remember that in Contact Mode, increasing the Setpoint increases the force on the sample. Minimizing the imaging force is recommended to prevent damage to the sample and the probe tip. 17. Set desired Scan Size, Scan Angle, and Offsets Page 5 of 6 Revision 7

6 Image Capturing 1. Choose Capture Filename from the RealTime pull down menu 2. Choose your directory to store the image, and enter a filename for the image. Note: directories must be created in Windows outside of the AFM software. Click OK. 3. Click on the camera icon to begin capturing an image. The image will begin capturing at the beginning of a scan frame. To move the probe to the beginning of a scan frame, click on the frame up or frame down icon 4. When capturing, the status bar at the bottom of the screen will indicate Capture: On, and when the capture is completed, it will indicate Capture: Done When you are finished: 1. Click on the Withdraw icon to stop scanning Engage Withdraw 2. Open the instrument cover 3. Select the Navigate window a. Raise the Probe head away from the sample using the Z-motor up arrow in the Navigate window b. Move the stage to the load position (completely out from under the scanner head) using the X-Y stage arrows in the Navigate window 4. Unload your sample 5. Remove the cantilever holder from the end of the scanner head and unmount your probe (Store your probe in your personal Gel-Pak storage box) 6. Close the instrument cover 7. If you wish to save changes to the workspace, Choose File/Save Workspace As and give the file a new workspace name. DO NOT save changes to the SMIF default workspaces 8. Exit Nanoscope software 9. Logout of the Log Usage system on the SMIF web site Page 6 of 6 Revision 7