The following is a description of the calibration method for low-temperature scanning probe microscopes:

1、 Calibration of Environment and Basic Settings

1. Temperature stability verification: As the equipment needs to operate in a low-temperature environment, the first step is to ensure precise temperature control of the refrigeration system. Place the standard temperature sensor near the sample stage and monitor its fluctuations at the set temperature. In an ideal state, temperature fluctuations during long-term operation should be controlled within a very small range. If the fluctuations are too large, it is necessary to adjust the parameters of the refrigeration machine or check whether the insulation layer is damaged.

2. Vibration isolation verification: Even small vibrations can interfere with the scanning accuracy of the probe. After enabling the shock-absorbing table, sensitive equipment such as laser interferometers are placed to detect the amplitude of table vibration. By adjusting the parameters of the shock-absorbing device, the vibration is reduced to a low level to ensure a smooth scanning process.

2、 Key performance calibration of probes

1. Morphology calibration: Select standard samples with known periodic nanostructures, such as grating diffraction templates. Obtain images at different scanning ranges, compare the actual measured feature sizes with the nominal values, and correct the displacement accuracy of the piezoelectric ceramic tube driven probe to eliminate deformation distortion caused by nonlinear errors.

2. Force curve calibration: Using a microcantilever beam with a known elastic coefficient as a mechanical reference. In tap mode, gradually change the distance between the probe and the sample, record the amplitude and phase of the cantilever beam as a function of distance, fit the true force distance relationship, and correct the force measurement deviation caused by factors such as temperature induced changes in the elastic modulus of the cantilever beam.

3. Current calibration (for conductive samples): Connect a precision current source to a preamplifier, apply a series of known currents to the probe tip, synchronously record the feedback signal strength, draw a standard curve, and facilitate accurate quantification of electrical parameters such as tunneling current in the future.

3、 Optical auxiliary system calibration

If equipped with an optical microscope for assisted positioning, objective calibration is required. A crosshair target with precise markings is fixed on the mobile platform, and different magnification lenses are switched for observation. The optical system is adjusted until the center of the field of view coincides with the coordinate origin, and the markings are undistorted, ensuring that the visual observation area accurately corresponds to the working range of the scanning probe.

4、 Regular comprehensive verification

In addition to the aforementioned specialized calibration, regular overall performance evaluations are also required. Using a single crystal silicon wafer as a comprehensive test sample, perform multiple rounds of scanning tasks continuously, covering a wide range of overview to small area fine imaging, to verify repeatability and consistency; Simultaneously cross compare the measurement results of different probes in the same area to identify probes with individual differences exceeding the tolerance.

The calibration of low-temperature scanning probe microscopy requires comprehensive consideration of environmental stability, probe core performance, and auxiliary system synergy. Through multidimensional and periodic professional calibration operations, it can ensure that the precision instrument provides reliable microscopic characterization data under complex working conditions.