Uniformity optimization techniques for rapid thermal processing systems

This paper presents two efficient robust methods for uniformity optimizatio n of rapid thermal processes. Both of these methods involve the reuse of em pirical response surfaces linking zone powers to measured process data crea ted on a baseline system. The first method uses fossilized gain matrices fr om the baseline system, while the second method involves customization of t he baseline response surface for each system. The approaches use the respon se surfaces for iterative modification of zone powers to reduce the process nonuniformity on successively processed wafers. These methods are applied to the optimization of rapid thermal oxidation processes on several lamp-he ated rapid thermal processing systems. Most of the uniformity improvement i s obtained with the first two optimization runs; in some instances, the pro cess is optimized to less than 1% 1-sigma nonuniformity with the use of jus t two wafers. Because the response surfaces from the baseline system can be reused for all similar systems, considerable savings in time and wafers ar e realized.