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Maintenance, Troubleshooting and Warranty

Maintenance

340 Dimension 3100 Manual Rev. D

18.1.2 Calibration

A description of the complete scanner calibration is located in a separate chapter. In general the

scanner’s calibration should be checked every three months. The main change in calibration will be

the loss of piezo sensitivity in the ﬁrst year of use. This is an expected behavior. Loss of 10-15% of

the initial scan size is common.

Inspections and Procedures

Noise Test Procedure

Although a noise test is performed prior to shipment and during a new installation, this test is useful

to periodically test the instrument’s performance in your lab. Increases in the noise level of the

instrument are typically due to some sort of environmental change such as the introduction of new

equipment in proximity of the D3100 stage. The D3100 system itself is historically not prone to

degrade over time, although changes to the environment are a common source of noise.

Because the Dimension 3100 is sensitive to vibration, it is often a convenient tool for checking the

performance of the vibration isolation system. The following test can be performed under ambient

conditions or while an external noise source is applied to the ﬂoor.

1. Install a new cantilever and engage in TappingMode on a Si wafer (500nm to 1µm scan

size). You can also image the substrate of a silicon probe. The probe can be mounted to a

small sample AFM puck with double-sided tape and held to the stage magnetically. The only

limit to this sample is that the vacuum seal between the chuck and the sample won’t be

tested.

2. Set the Z limit to 55V (~1µm). Set the Samples/line to 512.

3. Set the gains as low as possible, while still maintaining a good image with visible surface

roughness. Do not lower the Integral and Proportional gain below 0.2; the LookAhead

gain should be 0.

4. Change the Scan size to 1nm and capture an image. The Scan rate is not important for this

Scan size. You can set the Scan rate to 10Hz to save time. If you have low frequency noise,

you may want to set the Scan rate to 2Hz so that you can see at least a few periods (longer

time base).

5. Perform a first order Flatten Auto. Then, run the roughness measurement. The RMS value

should be typically 0.5Å.

An easy way to analyze noise is to use the Section Analysis function. If you draw a line that is

perfectly horizontal, the one dimensional Fourier plot will show you what frequencies are

contributing to your noise. Remember that when the Scan size is this small, you no longer have an

image but rather a temporal graph of the Z displacement.

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