Temperature control strategies for RTP systems

A simulation of rapid thermal processing (RTP) is made to investigate the accuracy of various control schemes. The simulated RTP process is chemical vapor deposition (CVD) of polycrystalline silicon over an oxide. The simulated control schemes are open loop control, pyrometer control, pyrometer control with corrected emissivity, and open loop control with the programmed lamp heating. Wafer temperature variation and final film thickness are predicted by the simulation. Based on these results, programmed open loop control is probably the best control scheme. An experiment confirms the results and shows reduced wafer temperature variation.<
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