Modeling, Optimization and Control of the Selective Plasma Etching of Silicon over Silicon Dioxide

The selective etching of Si over SiO2 in a CF4/O2 plasma has been studied using simulation and optimization. A showerhead plasma reactor was modeled as a well-mixed reactor, which was follwed by development of an otimal recipe. The optimizer, based on the generalized reduced gradient method, calculated optimal etch recipes using a set of mean values for the uncertain parameters. The-optimal end-point of each recipe step was then estimated using moving average control chart methodology.