Integrated real-time and run-to-run control of etch depth in reactive ion etching

Reactive Ion Etching (RIE) is a common process step in semiconductor manufacturing, yet the underlying mechanisms remain poorly understood. Our goal is to reduce the variance of etch characteristics by integrating real-time and run-to-run control of plasma and process variables. The run to run controller suggests plasma variable set-points based on the wafer characteristics of the previous run. The real-time controller maintains the suggested plasma variables by manipulating the process inputs during the etch. We have demonstrated the integrated control architecture for rejecting oxygen and loading disturbances in an Applied 8300 Hexode Reactor during a polysilicon etch.