Reaction kinetics and reactor modeling of the plasma etching of silicon

Abstract

AbstractA model including the effects of diffusion and convection can be used to predict the etch rate of crystalline silicon in a plasma discharge of nitrogen trifluoride. The case of a radial flow reactor with crystalline silicon wafers located at discrete positions can be solved using a finite‐element solution to a boundary value problem. Such a model is useful to predict the effects of pressure, flow rate of etchant gas, percent silicon exposed, and wafer position on both inter‐and intrawafer etch rates. It was found from modeling that greater uniformity in etch rate is achieved by lowering the pressure and percent exposure of silicon, and to a lesser degree the volumetric flow rate.