SIMULATIONS OF A FEEDBACK-CONTROL SCHEME FOR AN INDUCTIVELY-COUPLED PLASMA SOURCE FOR ETCHING APPLICATIONS

Processing large area wafers with inductively coupled plasma sources w ill require some form of real-time control. The design of such a contr ol system requires a detailed knowledge of the process transfer functi on, i.e., process gains and the response time of the process to contro llers and disturbances. In this paper, a feedback control system is pr oposed and investigated in which two or more independently powered and controlled coils are used to control a density measurement-based unif ormity and the density of a species in an inductively coupled plasma r eactor which is operating in a reactant-limited regime. Stability limi ts and the utility of this control scheme are investigated using zero and two-dimensional models.