Run-to-run control schemes for CMP process subject to deterministic drifts

During IC fabrication, the chemical-mechanical polishing (CMP) process usually suffers from a drift in the run-to-run removal rate due to the wear of the polishing pad. In this paper, two run-to-run control schemes, the predictor corrector control (PCC) and adjusted exponentially weighted moving average (d-EWMA) schemes, for processes under deterministic drifts are presented. The control performance of both schemes is analytically derived and the determination of the optimal control parameters is provided. Validation results using the field CMP data demonstrate the control effectiveness of both control schemes.