Measurement of Micro-Roughness on Si Wafer Surface Using System for Measuring Particle Diameter by Light-Scattering Method

Abstract

This paper proposes a method of measuring for a microroughness on a bare silicon (Si) wafer surface by using the measuring system developed for measuring nanoparticle diameter with a light scattering method. This method is based on the principle of determining microroughness by measuring the scattered light obtained when the laser spot is scanned on the surface of a Si wafer, assuming that the surface is consist of nanoparticles. Average of roughness values in the sub-nanometer order on a Si wafer surface can be obtained by this method. To evaluate this method, a relative measurement for microroughness on a Si wafer surface was established with the present measuring system, an Atomic force microscope (AFM) and a phase-shift interferometer. Consequently, it was verified that the values measured by the method and AFM are correlated, and then it was verified that the method is effective in measuring microroughness. Moreover, measurement for a washed Si wafer surface using a wet cleaning method was attempted in order to evaluate the effect of the surface roughness on a Si wafer measured using this method and AFM. As a result, it was verified that this measuring method could measure micro-roughness on a Si wafer surface.