Modified double EWMA approach for mixed product run-to-run CMP process control

Advanced process control (APC) has been recognized as a proper tool for maximizing profitability of semiconductor manufacturing facilities by improving efficiency and product quality. Run-to-run (RtR) process control with good quality and reliable performance for APC applications are most applicable. Chemical mechanical planarization (CMP) is part of critical processing module in semiconductor manufacturing. This paper proposes a new RtR control scheme, modified double EWMA controller (m-dEWMA), which is adaptive to the mixed product CMP processes. The m-dEWMA controller combined thread dEWMA with the drift compensation scheme to deal with the drift and shift disturbances caused by tool and products, respectively. Comparing recently mixed product control schemes: threaded EWMA controller, JADE control and threaded prediction correction controller (threaded PCC), the simulation results show that the m-dEWMA has better control performance than other controllers. The experiment results revealed that the m-dEWMA controller improves the wafer uniformity significantly in mixed product CMP process.