Issues and solutions for applying process control to semiconductor manufacturing

To follow the historical trend of 30%/function per year reduction in cost of integrated circuits and to meet the future processing challenges, semiconductor processing equipment must include improved control systems and semiconductor manufacturers must deploy more advanced control techniques. In this paper, the challenges of applying process control to semiconductor processing will be examined. Specifically, the various sources of variation which need controlling and diagnosing will be presented. The variation due to physical process changes will be introduced first, and their dynamics will be clarified. Current control practices and metrology limitations will then be reviewed, and the issues for achieving tight control that these practices and limitations generate will be highlighted. The paper will conclude with some examples of and suggestions for successful application of process control.