Calibration References

As described in the section on SPM Calibration Theory, each scanner exhibits its own unique sensitivities; therefore, it is necessary to precisely measure these sensitivities to establish software parameters for controlling the scanner. This task is accomplished with the use of a calibration reference:

A calibration reference, also called a calibration standard, consists of a platinum-plated silicon substrate with a regular series of pits of a given depth (typically 180 or 200 nm). The pits are spaced apart on 10 μm centers. Other similar surfaces are available with different dimensions. Atomic scale calibrations are generally carried out with mica or graphite, which exhibit very regular atomic lattices. Calibration references serve as measuring sticks with which to gauge scanner displacement for a given voltage.

The SPM should be capable of measuring a calibration reference with an accuracy of 2 percent or better while scanning at the maximum Scan size setting. Using fine calibration techniques, it is possible to calibrate the SPM with even greater accuracy.

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