Computational algorithm for dynamic optimization of chemical vapor deposition processes in stagnation flow reactors

There are potentially great benefits to developing materials processes that deliberately vary process conditions such as temperature, or flow rates, d uring the course of the process. Transient processing holds the promise of reducing manufacturing cost and the possibility of producing material syste ms that would be infeasible to manufacture with steady processes. Once the notion of transient processing is embraced, there is a need and opportunity to develop optimal trajectories through which the process will proceed. In this paper, a stagnation flow dynamic optimization algorithm for two chemi cal vapor deposition processes is demonstrated. The first example seeks to control film composition during the deposition of yttrium-barium-copper oxi de films, in which a wafer temperature transient is imposed. Transient traj ectories of precursor flow rates are determined by optimization, so that th e correct flux ratios of yttrium, barium, and copper atoms to the surface a re maintained. The second example determines trajectories that minimize the cost associated with multiple competing objectives during the deposition o f a copper film. Time varying trajectories of copper precursor concentratio n and the inlet flow velocity are computed so as to minimize a composite co st function that considers precursor utilization and process throughput. (C ) 2000 The Electrochemical Society. S0013-4651(99)10-034-X. All rights rese rved.