Instruction manual

Calibration, Maintenance, Troubleshooting and Warranty
Calibrating Z
304 MultiMode SPM Instruction Manual Rev. B
15.8.6 Calculate Retracted and Extended Offset Deratings
Piezoelectric materials exhibit greater sensitivity at higher voltages. In the steps outlined above, the
Z-axis calibrates while scanning near the middle of its voltage range (i.e., Z Center Position ~ 0
V). In this section, you will calibrate the Z-axis piezo while extended and retracted to offset the
increased sensitivity.
1. Select Engage under the Motor pop-down menu or click on the ENGAGE icon.
2. Use the Realtime > Motor > Tip Up button until the Z Center Position reads 100V (±5V).
Note: By using the motor to move the tip up, the feedback loop forces the Z-axis
piezo to extend to continue its tracking of the surface.
3. Refer to the steps above (Section 15.8.2 - Section 15.8.3) to determine the measured depth of
the calibration standard with a 100V Z Center Position.
4. Record the measured depth. If the depth measured by the extended piezo is off by more than
two percent, continue on to Step 5 - Step 8.
Note: The measured depth should read 200nm on a Veeco 10µm silicon calibration
reference.
5. Select the Realtime > Microscope > Calibrate > Z option to display the Z Calibration
panel
6. Click on the Extended offset der parameter.
7. Perform the following calculation:
For example, if the current offset equals 4% and the measured depth equals 175nm, then:
8. Enter the new percent value (from above example, 19%) for the Extended offset der
parameter in the Z Calibration panel.
Note: The procedure for calculating and setting the Retracted offset der is exactly
the same as for the Extended offset der; however, the piezo must be retracted
by 100V.
9. To calculate the Retracted offset derating, use the Tip Down button in the Motor Control
panel to retract the piezo. Retract the Z Center position to -100V (+/-5V), then repeat Step 3
- Step above.
(1 + current offset der)
200nm
meas. depth
—1
(1 + 0.04)
200nm
175nm
—1
= 0.19