Comparative study on the nonperiodic and periodic gratings for scanning probe microscopy drift measurements

Performances of a special nonperiodic grating (NPG) and a conventional periodic grating (PG) for scanning probe microscopy (SPM) drift measurements are compared. Experimental results verify that the NPG has the advantages of robust measurements and large measurable range. The correlation peak contrast of the SPM image of the fabricated NPG reaches 17.8, which enables enough stable drift measurement by correlation analysis of sequentially scanned images. The measurable drift range relies on the grating size of the NPG, while it is limited by the grating pitch of the PG. For SPM drift characterization, the NPG prevails against the ordinary PG since both the peak contrast and the measurable range can be easily improved by more than one order of magnitude.