Performance analysis and comparison between two forms of double EWMA controllers in industrial process

The double EWMA (exponential-weighted-moving-average) controller, as one kind of R2R (Run to Run) controller has been widely used in the industrial process, especially in semiconductor manufacturing. In this paper, two forms of the most popular double EWMA controller are analysed and compared in terms of the stability conditions and long-run performance. We point out their own advantages and disadvantages in use and present each own applicable situations. Finally, a specific chemical mechanical polishing (CMP) process will be used as an example to illustrate the validity of our results.