Wafer by wafer control in CMP system with metrology delay

Chemical mechanical planarization(CMP) has become part of important processing module in semiconductor manufacturing due to the shallow trench isolation technique. It is known that many different sources of variations are commonly found in CMP process. Hence the run-to-run control scheme which can specify how the recipe for the process should be updated is appropriate for CMP process control. This work tries to treat the issue of practical application of run-to-run control with metrology delay for CMP system. The module characteristics and real operating conditions of CMP processes are first studied and demonstrated by CMP data collected from fab. By considering the effects of metrology delay, the process model and parameters of the observer are properly modified to improve the performance of the double EWMA controller. To sum up, based on the collected CMP data, the process capability index C_pk can be enhanced several times by use of the proposed run-to-run control approach