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Proceedings Paper

Characterization Of Voting Suppression Of Optical Defects Through Simulation
Author(s): Kenny K.H. Toh; Chong-Cheng Fu; Kevin L. Zollinger; Andrew R. Neureuther; R. Fabian W. Pease
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Paper Abstract

Two-dimensional image simulation with SPLAT and resist profile dissolution simulation with SAMPLE are used to explore the suppression of large defects with voting in projection printing. The parameters chosen are for the Ultratech 1000 stepper due to the availability of experimental data with programmed defects. The results are stated in terms of feature and defect sizes in λ/NA where λ, is the wavelength and NA is the numerical aperture. Models based on 1) full resist dissolution simulation, 2) 30% clear field intensity of simulated images and 3) simple algebraic approximations are used. The case of using three votes on transparent defects placed at various locations in line patterns is studied in detail. An excellent fit between simulation and experimental results was obtained. It was also found that defect suppression with 3:1 voting is always a factor of 3 for small defects, and improves for larger defects except both when the partial coherence is less than 0.5 and when defects are within 0.2 λ/NA of a neighboring feature. Voting may be used to overcome mask defects which are so large that they have bridged patterns on the wafer. For 10% linewidth variation, the use of voting raises the critical defect size from 0.24 to 0.5 λ/NA. The effects of process bias and overlay are also explored.

Paper Details

Date Published: 1 January 1988
PDF: 9 pages
Proc. SPIE 0922, Optical/Laser Microlithography, (1 January 1988); doi: 10.1117/12.968413
Show Author Affiliations
Kenny K.H. Toh, Univ. of California Berkeley (United States)
Chong-Cheng Fu, Stanford University (United States)
Kevin L. Zollinger, Ultratech Stepper (United States)
Andrew R. Neureuther, Univ. of California Berkeley (United States)
R. Fabian W. Pease, Stanford University (United States)

Published in SPIE Proceedings Vol. 0922:
Optical/Laser Microlithography
Burn Jeng Lin, Editor(s)

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