Surface roughness measurement accuracy analysis of grinded silicon wafer by white light scanning interferometry (WLSI)

Abstract

White light scanning interferometry (WLSI) is a fast, noncontact, high-precision method to measure three-dimensional (3D) surface profile and extensively used in roughness measurement of ultra-precision machined surface. However, due to Rayleigh criterion, the lateral resolution of WLSI is limited to hundreds of nanometers. It is hard to measure rough surfaces with delicate details that adjacent distance less than lateral resolution. Also, WLSI can’t measure profiles with large surface gradient for no light reflected and received by objective lens. In this work, with a proposed simulation measurement model, surface gradient error and lateral resolution error on measuring result of WLSI is studied by simulating the response characteristics of sinusoidal signal, square signal, sawtooth signal and actual surface profile of grinding silicon wafer measured by AFM respectively. The effectiveness of the simulation model is verified by comparing the simulation results with the experimental results. The mechanism of surface gradient error and lateral resolution error is revealed from the perspective of simulation analysis, which has certain guiding significance for the future research of error analysis on white light scanning interference.