Influences of Organic Additive Molecular Weight in Colloidal-Silica-Based Slurry on Final Polishing Characteristics of Silicon Wafer

Abstract

The influence of molecular weight of hydroxyethyl cellulose (HEC) on the surface qualities of a silicon wafer during final-touch polishing was investigated. Using electro-light scattering, contact-angle measurement, force-distance measurement in AFM, and X-ray photoelectron spectroscopy, confirmed that HEC is adsorbed onto the colloidal-silica-abrasive surface and the silicon-wafer surface and that the adsorption amount increases in accordance with HEC molecular weight. With the increase in HEC molecular weight in the slurry, the number of remaining particles and surface roughness on the silicon wafer are greatly reduced by a firmly adsorbed thick polymer layers on the colloidal-silica-abrasive and silicon-wafer surface that forms with the addition of 250K-molecular-weight HEC to the slurry.