Agilent Technologies – Installation Training Nanotechnology Measurements Division Installation Training Dec 2007

Scanner Calibration Scanner Calibration Controls: Scanner calibration file pull-down Sensitivity Non-linearity Hysteresis Sensor calibration Enabled Reverse Offset Gain STM/AFM Preamp Sensitivity Servo Gain Multiplier Installation Training Dec 2007

Scanner Calibration The image to the left shows a typical image from an uncalibrated scanner. Notice how the features are bigger at the start of each scan line and the bottom of the image and how they reduce in size along each scan line and from bottom to top. This is typical behavior for a piezo scanner that has not had the non-linearity corrected. To correct the non linearity increase the non-linear term in the scanner calibration file if the features are larger at the start of the scan then at the end of the scan (line for X frame for Y) and decrease the non-linear term in the file if the features are smaller at the start and larger at the end of a scan. Scan direction Installation Training Dec 2007

Scanner Calibration The image to the left shows the calibration standard after the non-linearity correction has been completed. The next step is to correct for size of the features also known as the sensitivity correction. To do this correction measure the period of several features and use the following equation: Scan direction Installation Training Dec 2007

Scanner Calibration The image to the left shows the image after the scanner has been properly calibrated for non-linearity and sensitivity. Z is calibrated using the same equation that was used for the X and Y sensitivity but the depth or height of a known feature must be used instead of the lateral period. Scan direction Installation Training Dec 2007

Scanner Calibration Hysteresis correction requires the trace and retrace data to calibrate in the fast scan or X direction. Utilize the tool to line up the cursors on the images to help with this calibration. In the Y direction one must watch how the data is redrawn frame to frame to correct for Y hysteresis. Installation Training Dec 2007

Closed Loop Sensor Calibration – Z Axis Select Sensor As Topo in the Advanced tab of the Spectroscopy dialog. Set the Aux1 Input to Topography Select Force vs. Distance spectroscopy. Set the sweep range to the maximum allowed. Select infinite sweeps. Start sweeping the Z piezo full range. Installation Training Dec 2007

Closed Loop Sensor Calibration – Z Axis Adjust the Z sensor gain and offset so that the sensor appears similar to the data shown on the right below the Scanner Setup dialog. The sweep extents should be just about +/-10V for the maximum sensitivity and the sweep should be centered about zero. The Z Sensor Sensitivity term is calibrated while imaging a Z calibration standard with Sensor As Topo selected. The method is the same as it was for calibrating the scanner piezo Z axis but this term applies to the sensor instead. Installation Training Dec 2007

Closed Loop Sensor Calibration – X and Y Axes Initial Setup: False engage system Open two images windows Select X Sensor – No Flattening and Trace and Retrace Set Display Range to 20 and offset to 0 Set scan size to full range (square) Set scan speed to 1 l/s Set angle to zero Start scan and view Realtime Cross Section Installation Training Dec 2007

Closed Loop Sensor Calibration – X and Y Axes Adjust the X Sensor gain and offset as was done for the Z axis. The sensitivity will be calibrated by imaging a calibration standard with closed loop enabled and calibrating the X sensor Sensitivity using the same equation as was used for the open loop sensitivity correction previously. Y can be calibrated in the same manner but the Y sensor channel must be selected and the scan angle set to 90 degrees. The X sensor plot should appear as it does above. If it has the opposite slope check or uncheck the Reversed check box for that sensor. The Y sensor should increase as the scanner scans up with the angle set to 0. If it does not use the Reversed check box for the Y sensor. Installation Training Dec 2007

Scanning in Closed Loop After the X and Y sensors have been calibrated the scanner can be used for scanning in closed loop. In the Advanced tab of the Scan and Motor dialog Enable Closed Loop and adjust the I and P gains for X and Y as needed so the scan is linear and there is no hysteresis. If the gains are set too high the system will oscillate as it will if the servo gains are set too high. Installation Training Dec 2007