Modified EWMA Controller Subject to Metrology Delay in Semiconductor Manufacturing Processes

Abstract

Modified EWMA Controller Subject to Metrology Delay in Semiconductor Manufacturing Processes Chien-Hua Lin (林建華) Department of Statistics and Informatics Science, Providence University ? Due to the resource and capacity limitations of metrology equipment of IC manufacturing process, metrology delay is common for the practical implementation of run-to-run (R2R) control scheme. In the literatures, several papers had provided the efforts of using metrology delay data or virtual metrology (VM) prediction model on the transient behaviors and asymptotic stability of exponentially weighted moving average (EWMA) controller. However, these procedures still suffer from large bias and/or variation of process response variable. To overcome this difficulty, we proposed a modified EWMA controller to adjust the process by fully using the metrology delay data and VM information. An analytical expression of the process output of this controller and its long-term stability and short-term output performance are derived. Furthermore, under some specific parameter settings, a more comprehensive study is presented to illustrate that the proposed controller has the capability of reducing the total mean square error of process response variable comparing to the existing controllers. (joint work with Prof. Sheng-Tsaing Tseng and Hsiang-Fan Wang)