Multiresolution pattern detector networks for controlling plasma etch reactors

Ronald L. Allen; Randy Moore; Mike Whelan

doi:10.1117/12.221321

19 September 1995 Multiresolution pattern detector networks for controlling plasma etch reactors

Ronald L. Allen, Randy Moore, Mike Whelan

Proceedings Volume 2637, Process, Equipment, and Materials Control in Integrated Circuit Manufacturing; (1995) https://doi.org/10.1117/12.221321
Event: Microelectronic Manufacturing '95, 1995, Austin, TX, United States

Abstract

A critical step in semiconductor wafer fabrication is to halt a plasma reactor as soon as the etched film clears to expose the underlying layer. Typically, changes int he optical emissions spectrum are employed to detect this process endpoint. However, differences in plasma chemistry and reactor chambers, small exposed areas, and variations in wafer patterns complicate this control strategy. Our novel approach uses the characteristic local shape of spectral lines as a guide to finding endpoint. With the Haar wavelet representation, we model shapes over many resolutions. A network of pattern detector 'neutrons' runs real- time to locate these shapes and stop the etch process. This provides robust endpoint detection under widely varying reactor and wafer conditions. Our neural network endpointer has been successfully tested on data gathered for six months at a major wafer fabrication facility.

Citation Download Citation

Ronald L. Allen, Randy Moore, and Mike Whelan "Multiresolution pattern detector networks for controlling plasma etch reactors", Proc. SPIE 2637, Process, Equipment, and Materials Control in Integrated Circuit Manufacturing, (19 September 1995); https://doi.org/10.1117/12.221321

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