Height Calibration of Atomic Force Microscopes using Silicon Atomic Step Artifacts

摘要

The decreasing feature dimensions required in the semiconductor manufacturing industry are placing ever increasing demands upon metrology instruments. Atomic force microscopes (AFMs), which can have lateral resolution of 1 nm and vertical resolution of 0.1 nm or below, are being used increasingly as metrology tools in the semiconductor industry. Nanometer level accuracy with AFM metrology, however, remains challenging. The scales of an instrument must be calibrated to perform accurate pitch or height measurements, while surface roughness or feature width measurements are further complicated by the 'convolution' of the probe geometry with that of the sample. Although many commercial AFMs employ some form of position sensor (capacitance or split diode) to linearize scan motions and improve repeatability, the scales of these instruments must still be calbirated using some standard artifact. At present, no AFM standard artifacts exist which are actually calibrated using AFM because no instrument with the required accuracy has been available.