Grating Pitch Measurement Beyond the Diffraction Limit with Modified Laser Diffractometry

Abstract

The demand for accurate measurements of nanostructures is increasing for the microprocesses and nanotechnology used in the semiconductor industry. In this study, we present an improved method for measuring gratings with a pitch size lower than one-half of the laser wavelength by using a modified laser diffractometer (LD). In experiments, the modified LD with a 633nm laser is used to measure a grating with a 288nm pitch size. This result is compared with results measured by both a metrological atomic force microscope and the traditional LD with a 543nm laser. The validity of this method is demonstrated. The difference between the pitch size of 288nm obtained by these three methods is approximately 0.17 nm. (C) 2011 The Japan Society of Applied Physics