Method for Determining the Angle in Two Dimension Nanoscale: Pitch Grating

Abstract

A two-dimensional (2D) grating is useful for calibrating the accuracy of an electron microscope and atomic force microscope (AFM). An inter laboratory comparison has been carried out for measuring pitches and angles of 2D gratings with 292 and 1000nm pitches using both AFM and an optical diffractometer (OD). The grating angle at the 292nm pitch size was obtained at some of the laboratories by the conventional OD method. However, they could not measure the grating angle when the grating pitch was smaller than (lambda/2) x root 2, where lambda denotes the laser wavelength. We propose a diffraction angle rotation method of grating angle measurements. Using a precision rotary table along with diffractive light, we accurately measure a 2D grating angle for any pitch size larger than lambda/2. (C) 2011 The Japan Society of Applied Physics