Optimal control for increasing throughput in low pressure chemical vapor deposition

We present the application of optimal control theory to the process of low pressure chemical vapor deposition (LPCVD) on patterned surfaces. An optimally controlled CVD protocol is developed by employing an approximate feature scale model, based on the simultaneous one-dimensional Knudsen diffusion and chemical reaction description of LPCVD, for the specific problem of maximizing throughput for a specified step coverage. The corresponding control conditions for the reactor are obtained by an adaptive solution of the inverse problem for the reactor scale model. Rigorous process simulations demonstrate that the computed temperature and partial pressure trajectories provide good step coverage.