Simultaneous control of multiple nonuniformity metrics using site models and monitor wafer control

Present day semiconductor manufacturing processes are subject to tight specifications. High yields with tight process specifications require proactive, "drive to target", process control. As the size of the wafer in the semiconductor industry increases, nonuniformity across the wafer becomes a crucial yield limiting issue. Modeling nonuniformity in terms of the equipment settings permits calculation of recipes required to achieve the desired nonuniformity. Models for scaler metrics of nonuniformity, such as standard deviation, or range, do not capture all aspects of the nonuniformity (i.e., shape, symmetry, etc.). In this paper we describe the use of spatial models to quantify various measures of nonuniformity, and a controller to keep the nonuniformities within specifications. A flexible controller, called monitor wafer controller (MWC), has been reported previously for the control of semiconductor processes. Use of spatial models in conjunction with the MWC enables the simultaneous control of multiple nonuniformity metrics. The results of applying the MWC with spatial model to a Plasma Enhanced TEOS (PE-TEOS) deposition process on an Applied Materials Precision 5000 (AMT5000) reactor are presented. The controller has kept the interlevel-dielectric deposition process within specifications for over an year.