Real time statistical process control for plasma etching

The development and the application of a real-time statistical process control (SPC) scheme are presented. Based on time-series and multivariate statistics, this scheme can accommodate real-time sensor readings such as can be collected from a single-wafer plasma etcher via the SECSII communications protocol. The scheme has been successfully applied on a Lam Rainbow plasma etcher, and it has been able to detect internal machine shifts that cannot be seen with classical SPC procedures.<
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