Tighter process control of poly- and active-to-contact overlay registration via multilayer analysis

Peter M. C. Lee; Paul C. Knutrud

doi:10.1117/12.386453

2 June 2000 Tighter process control of poly- and active-to-contact overlay registration via multilayer analysis

Peter M. C. Lee, Paul C. Knutrud

Proceedings Volume 3998, Metrology, Inspection, and Process Control for Microlithography XIV; (2000) https://doi.org/10.1117/12.386453
Event: Microlithography 2000, 2000, Santa Clara, CA, United States

Abstract

As process technology in high volume production fabs hits the 180 nm window, overlay metrology of the most critical layers needs to be managed very carefully. As feature sizes and other device characteristics shrink, the overlay requirement becomes a larger component of the overall process specification. It is no longer sufficient to measure overlay for only two layers at a time. In no other part of the process is this more critical than the poly and active layer to first contact. The contact layer needs to be aligned to both active and poly within tight tolerances. Since adjustments to overlay for these levels are not independent, it is essential to understand the relationship between all three layers. TSMC in particular, because it is a foundry, is not able to optimize customer circuit design that would allow two-layer registration to be sufficient. Previously, the only method to accomplish this has been to make two sets of overlay measurements and having an engineer analyze the relative overlay between the three layers. The proposed solution to solve this problem is a multi-layer overlay measurement algorithm and measurement target. This paper will report on the analysis of the process improvements that have and can be achieved using this unique measurement capability.

Citation Download Citation

Peter M. C. Lee and Paul C. Knutrud "Tighter process control of poly- and active-to-contact overlay registration via multilayer analysis", Proc. SPIE 3998, Metrology, Inspection, and Process Control for Microlithography XIV, (2 June 2000); https://doi.org/10.1117/12.386453

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