2 June 2000 Sampling plan optimization for detection of lithography and etch CD process excursions
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Effective sample planning requires a careful combination of statistical analysis and lithography engineering. In this paper, we present a complete sample planning methodology including baseline process characterization, determination of the dominant excursion mechanisms, and selection of sampling plans and control procedures to effectively detect the yield- limiting excursions with a minimum of added cost. We discuss the results of our novel method in identifying critical dimension (CD) process excursions and present several examples of poly gate Photo and Etch CD excursion signatures. Using these results in a Sample Planning model, we determine the optimal sample plan and statistical process control (SPC) chart metrics and limits for detecting these excursions. The key observations are that there are many different yield- limiting excursion signatures in photo and etch, and that a given photo excursion signature turns into a different excursion signature at etch with different yield and performance impact. In particular, field-to-field variance excursions are shown to have a significant impact on yield. We show how current sampling plan and monitoring schemes miss these excursions and suggest an improved procedure for effective detection of CD process excursions.
© (2000) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Richard C. Elliott, Richard C. Elliott, Raman K. Nurani, Raman K. Nurani, Sung Jin Lee, Sung Jin Lee, Luis G. Ortiz, Luis G. Ortiz, Moshe E. Preil, Moshe E. Preil, J. George Shanthikumar, J. George Shanthikumar, Trina Riley, Trina Riley, Greg A. Goodwin, Greg A. Goodwin, } "Sampling plan optimization for detection of lithography and etch CD process excursions", Proc. SPIE 3998, Metrology, Inspection, and Process Control for Microlithography XIV, (2 June 2000); doi: 10.1117/12.386461; https://doi.org/10.1117/12.386461

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