A run-to-run film thickness control of chemical-mechanical planarization processes

With the continuing shrink of device geometries, tightly control of semiconductor manufacturing processes becomes a critical factor to improve the process performance, throughput and yield. In this paper, we present design, analysis and implementation of a run-to-run film thickness control scheme for chemical-mechanical planarization (CMP) processes. A predictor-corrector type of control law is utilized to regulate the CMP process time. The control algorithm uses the information of the monitor wafer removal rate and the consumable lifetime to compensate for process drifts and shifts. We also discuss a compensation method for CMP polisher head-to-head variations. The process results in a production fab show a significant improvement of CMP performance under the proposed control scheme.