Feedback control of polysilicon etching: controller design issues

Summary form only given. Feedback control can considerably improve the performance of rf plasma processing reactors. It has been recently demonstrated that plasma simulations can be useful in developing feedback control strategies and controllers. In this paper, we extend that work to address issues related to the improvement of controller design, experimental validation, and advanced control strategies for polysilicon etching in inductively coupled plasmas (ICP). The computational tool used in this study, the virtual plasma equipment model (VPEM), is based on a detailed 2-dimensional hybrid plasma equipment simulation. To validate the control aspects of the VPEM, we simulated a magnetic bucket ICP reactor currently being used for real time feedback control experiments at the University of Wisconsin. Results for the use of capacitively coupled power to control etch rate in real time will be discussed for both PID and PID-feed forward controllers.