Particle contamination on a silicon substrate in a SF6/Ar plasma

Abstract

Particle contamination on silicon wafers exposed to a SF6/Ar plasma is examined as a function of five critical plasma parameters using response surface methodology. Plasma parameters explored are 13.56 MHz rf power, pressure, process gas flow rate, 100 KHz wafer electrode power, and etch time. The experiment is conducted in a Tegal MCR-1 single wafer reactor operated in the triode mode. Particle count is found to increase linearly as a function of 13.56 MHz rf power, 100 KHz power, and etch time. Also, the particle count has a quadratic dependence as a function of process gas flow rate. Surprisingly, in the pressure range explored, particle deposition on the wafers is found to be independent of pressure. Auger and EDX chemical analysis of the particles reveals the presence of silicon, fluorine, oxygen, sulfur, and aluminum.