Pitch Measurement by Traceable Atomic Force Microscope

Abstract

A Traceable Atomic Force Microscope (TAFM) to calibrate the pitch standards is presented. The TAFM consists of an atomic force microscope, a three-axis active compensation flexure stage, two laser interferometers, an L-shape mirror, a vibration isolator, and a super-Invar metrology frame. A test specimen is laid on the same plane of laser interferometers to eliminate the Abbe-offset. The displacements of X and Y axes are taken by the laser interferometers, the Z movement is controlled by AFM cantilever and the displacement is taken by a capacitance sensor while the flexure stage moves the specimen in X and Y axes motions. A water circulator is used to control the TAFM at 20 • C. Measuring results of a standard pitch sample show that this TAFM can be used for measuring of pitch standards. A pitch standard with nominal value of 292 nm was served as a test sample. The combined standard uncertainty was 1.2 nm.