Analyses and Modeling of a Wet-Chemical-Etch Process on Rotating Silicon Wafers with an Impinging Etchant Jet

Abstract

We investigate wet chemical etching of bare silicon wafers using a configuration where the wafer rotates and the etchant is supplied to the wafer by a nozzle positioned above the wafer center. The purpose of this study is to identify the change of the etch-rate profile on the wafer in relation to the parameters of speed of rotation, etchant flow rate, and etchant temperature. All of them influence the flow velocity of the etchant on the wafer. As a consequence, we propose to use a simplified model that captures the etchant flow velocity on the rotating wafer in sufficient detail to imply the etch-rate profiles for the wet-chemical-etching process of bare silicon wafers. We validate our approach against measured etch-rate profiles for a wide variety of parameter settings.