CALIBRATION AND APPLICATIONS OF A HIGH-PRECISION PIEZO SCANNER FOR NANOMETROLOGY

Piezoelectric tube scanners are being used with many scanning probe microscopes for scanning sample surfaces in three dimensions. Since the piezo effect has nonlinearity, hysteresis, and drift, difficulties will occur with distortion, reproducibility, and accuracy of measurements (Barrett and Quate 1991). Correction procedures, which are not based on improvement of linearity of scan movements, will still be affected by remaining nonlinearities of an order of a few percent. The manufacturing of increasing amounts of miniaturized structures for microsystems and semiconductors, as well as certification of standards and measuring devices, will, however, require higher accuracy of profile measurements in the submicrometer and nanometer range. This publication describes a scanner which has a nonlinearity of < 0.05%, a procedure for calibration and detection of nonlinearity, as well as some applications. The calibration technique is based on the fact that manufacturing and measurement of optical diffraction gratings can be very well controlled, allowing light wavelength as an indirect reference in the nanometer range (Antrak 1993, Bartzke et al. 1993, Grunewald 1993, Hutley 1982).