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Impact of local variability on defect-aware process windows
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Paper Abstract

CD-based process windows have been an analysis workhorse for estimating and comparing the robustness of semiconductor microlithography processes for more than 30 years. While tolerances for variation of CD are decreasing in step with the target CD size, the acceptable number of printed defects has remained flat (Hint: Zero) as the number of features increases quadratically. This disconnect between two key process estimators, CD variability and defect rate, must be addressed. At nodes that require EUV lithography, estimating the printed defects based solely on a Mean CD (“Critical Dimension”) process window is no longer predictive. The variability / distribution of the printed CDs must be engineered so that there are no failures amongst the billions of instances, rendering the Mean CD, often measured on just hundreds or thousands of instances, a poor predictor for outliers. A “defect-aware” process window, where the count of printed defects is considered in combination with more advanced statistical analysis of measured CD distributions can provide the needed predictability to determine whether a process is capable of sufficient robustness. Determining process robustness where stochastics and defects are taken into account can be simplified by determining the CD process margin. In this work we study dense contact hole arrays exposed with 0.33NA single exposure EUV lithography after both the lithography and etch steps. We describe a methodology for expanding the analysis of process windows to include more than the mean and 3σ of the data. We consider the skew and kurtosis of the distribution of measured CD results per focus-exposure condition and compare / correlate the measured CD process window results to the CD process margin.

Paper Details

Date Published: 14 March 2019
PDF: 15 pages
Proc. SPIE 10957, Extreme Ultraviolet (EUV) Lithography X, 109570H (14 March 2019); doi: 10.1117/12.2514719
Show Author Affiliations
Mark John Maslow, ASML Netherlands B.V. (Netherlands)
Hidetami Yaegashi, Tokyo Electron Ltd. (Japan)
Andreas Frommhold, IMEC (Belgium)
Guido Schiffelers, ASML Netherlands B.V. (Netherlands)
Felix Wahlisch, ASML Netherlands B.V. (Netherlands)
Gijsbert Rispens, ASML Netherlands B.V. (Netherlands)
Bram Slachter, ASML Netherlands B.V. (Netherlands)
Keisuke Yoshida, Tokyo Electron Ltd. (Japan)
Arisa Hara, Tokyo Electron Ltd. (Japan)
Noriaki Oikawa, Tokyo Electron Ltd. (Japan)
Abhinav Pathak, IMEC (Belgium)
Dorin Cerbu, IMEC (Belgium)
Eric Hendrickx, IMEC (Belgium)
Joost Bekaert, IMEC (Belgium)

Published in SPIE Proceedings Vol. 10957:
Extreme Ultraviolet (EUV) Lithography X
Kenneth A. Goldberg, Editor(s)

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