Advanced Process Control in Semiconductor Manufacturing

Kostas S. Tsakalis

Supported by SEMY Engineering Inc. (subsequently part of Semitool, Brooks PRI, Applied Materials) under grant No. SEI-950815-MBTC-001,...,6
Best products Award (picture)


This work provides an integrated approach for modeling and robust multivariable controller design, with application to temperature control of diffusion and CVD furnaces. Modeling relies on input-output data, collected in a preliminary identification experiment at the desired operating conditions. An important component of the identification is the computation of uncertainty bounds that describe the confidence limits of the model, in a manner consistent with robust control theory. The results of the identification are then used to design an H-infinity controller with a cascade, hierarchical structure. The final implementation of the controller also includes mechanisms to prevent integrator wind-up. Special emphasis is placed on automating the procedure --for classes of furnaces-- so that, potentially, it can be used by non-experts on the field. Implementations include several industrial furnaces. Experimental results demonstrate the success of the approach as well as the good agreement between predicted and actual closed-loop behavior. 


Related results:

M. Yelverton, K. Stoddard, B. Cusson, T. Timmons, "Improving Diffusion Furnace Capability Using Model-Based Temperature Control in Production Environment," 6th ISSM, San Francisco, Oct. 97.

More Details (Brief description of the project and typical experimental results, courtesy of SEMY Eng. Inc.)