Stability analysis of double EWMA run-to-run control with metrology delay

摘要

The double exponentially weighted moving average (d-EWMA) feedback controller is a popular algorithm for controlling semiconductor manufacturing processes which have a deterministic drift. Like all controllers, a poorly tuned d-EWMA controller can result in system instabilities. This paper examines stability bounds for the tuning parameters of both single input-single output (SISO) and multiple input-multiple output (MIMO) d-EWMA controllers when there is plant-model mismatch and delay between product manufacturing and product metrology. In addition, a simulation of chemical mechanical planarization run-to-run (R2R) control is included to illustrate the importance of performing stability analysis in choosing d-EWMA tuning parameters.