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Proceedings Paper

Characterization Of The Ultratech Wafer Stepper
Author(s): Ron Hershel; Ron Voison
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Paper Abstract

A brief characterization of the Ultratech Model 900 wafer stepper is presented. Excellent control critical dimensions for 1-gum minimum features is accomplished by using a broad spectral bandwidth for exposure which minimizes standing wave effects and by using numerical aperture of 0.315 illuminated with coherence factor of 0.45. Minimal variation in linewidth is seen over 5000A to 8000A poly and metal steps with little evidence of standing wave patterns in the resist profiles. A large depth of focus is obtained with a highly corrected 1:1 lens design which keeps astigmatism and field curvature below 0.5um. The automatic site-by-site alignment system on the Model 900 has proven extremely reliable at all wafer levels with a repeatability better than 0.16um (2 sigma). Lens-to-lens distortion below 0.2um (2 sigma) results from the inherent symmetry in the folded 1:1 design and from careful lens fabrication. A precision lenedistortion test is described with a 2 sigma error below 0.04um and the overlay distortion for the three Ultratech lenses is presented.

Paper Details

Date Published: 13 September 1982
PDF: 8 pages
Proc. SPIE 0334, Optical Microlithography I: Technology for the Mid-1980s, (13 September 1982); doi: 10.1117/12.933559
Show Author Affiliations
Ron Hershel, Hershel Consulting Inc. (United States)
Ron Voison, Ultratech Corporation (United States)

Published in SPIE Proceedings Vol. 0334:
Optical Microlithography I: Technology for the Mid-1980s
Harry L. Stover, Editor(s)

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