Exploring ISSG process space [Si oxidation

Abstract

This paper describes a computational-modeling effort that investigates silicon oxidation using In-Situ Steam Generation (ISSG). Using a fluid-mechanical boundary-layer model, we have simulated the chemically reacting flow in the Applied Materials Radiance RTP reactor. The model incorporates an elementary gas-phase chemical reaction mechanism that describes the essential free-radical chemistry that is responsible for ISSG. Comparing measurements of oxide thickness and uniformity with modeled flow fields over numerous process conditions for both 200 and 300 mm wafers, we observe a strong correlation between oxide physical characteristics and atomic-oxygen number density. Through this correlation, we find that ideal ISSG process conditions are those that result in a weak, diffuse reaction zone that spans the diameter of the heated wafer. We then expand the modeled process space to conditions outside of common ISSG practice. Varying hydrogen concentration, reactor pressure, reactant flow rate, and wafer temperature, we have extensively mapped the process space and identified process conditions that are robust to process variations.