Model based predictive control in RTP semiconductor manufacturing

Temperature control in single-wafer semiconductor reactors has become a hot topic. The interest in the subject illustrates the fact that the temperature measurement and control issues are far from trivial. This is due to the reactor design which is inherently non-isothermal, to the principal difficulties in measuring wafer temperature (or film thickness) in real-time and to the typically large interaction present between zones in radiantly heated systems. CVD-RTP (chemical vapor deposition-rapid thermal processing) reactors offer a challenge to control engineers in that the control of temperature uniformity over the wafer surface is of utmost importance for the next generation of processing equipment. This paper presents a solution based on the methodology of model based predictive control.