Influence of the Top Chamber Window Temperature on the STI Etch Process

Abstract

During shallow trench isolation etching it was found that etch stop appears at the center of a 300 mm wafer as the temperature of the top quartz window of the etch chamber exceeds 85°C. We attributed the etch stop to redeposition of some low-volatile SiOxCly etch products. At low quartz window temperature part of the products are deposited on it, but as the window temperature rises well above the wafer temperature (which is constant at 60°C), the products primarily are deposited on the wafer causing the etch stop.