Test Structures

Distortions in scanned images result from non-linearity, hysteresis, and creep of piezoceramics response to applied voltage.

To measure these distortions you can use TGX01 grating. It comprises a chessboard-like array of square pillars with edge shape determined by the silicon crystal structure. This ensures an edge roughness value of about several nanometers.

Fig.1 shows typical images of the grating before and after the correction of non-linearity.

Fig.1a 20x20 µm image of TGX01 before correction of non-linearity.

Fig.1b 20x20 µm image of TGX01 after software correction of non-linearity.

Due to its precise geometry, the grating can be used to measure distortions caused by scanner non-linearity over the whole scanning range. Non-linearity as a function of X, Y position is shown in Fig.2 for a 40 x 40 µm scan.

Fig.2 Non-linearity versus X, Y position.

Fig.3 Image of TGG01 taken by P4-SPM-MDT model of SOLVER. Using a cross section of the image one can detect non-linearity and angular distortion (the apex angle is formed by (111) planes and should be equal to 70°). The curvature radius of the edge in the image is equal to the sum of the curvature radii of the cantilever tip and the step edge.

To determine vertical non-linearity of your microscope, scan the gratings of TGS01 set - TGZ01, TGZ02, and TGZ03.

To detect non-linearity and angular distortion, use TGG01 grating (Fig.3). Lateral faces of the steps of TGG01 are formed by (111) planes of Silica. The apex angle is equal to 70°.

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