Cycle prediction EWMA run-to-run controller for mixed-product drifting process

In semiconductor manufacturing processes, mixed- products are usually fabricated on the same set of process tool with different recipes. Run-to-Run controllers which based on the exponential weighted moving average (EWMA) statistic are probably the most frequently used in industry for the quality control of certain semiconductor manufacturing process steps. However, for mixed- product drifting process, if the break length of a product is large, then the process output at the beginning runs of cycle 1,2,... will be far deviated from target which will lead to a possible high rework rate and lots of waste wafers. Therefore, this study aims to develop a cycle prediction EWMA (CP- EWMA) approach to deal with the problem of large deviations in the first few runs of cycle 1,2,... Simulation study showed that the proposed approaches are effective.