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Proceedings Paper

Deep-UV Photolithography With a Small-Field 0.6 N.A. 'Microstepper'
Author(s): Chris Spence; William G. Oldham; William N. Partlo; John H. Bruning; David A. Markle; Richard Hsu
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Paper Abstract

A 'Microstepper' is being constructed at U.C. Berkeley as a flexible lithography tool to study the possibilities and problems of photolithography using refractive optics with a KrF Excimer laser light source. This paper will present data on the performance of the optical system. 0.3μm line/space elbows were clearly resolved in thin MP2400 resist. Single-pulse, speckle-free images were achieved by modifying the condenser design and using a high-sensitivity chemical-amplification resist. Optical noise was found to be a problem. We were able to substantially reduce this noise by using a moving diffuser. Alternatively, incorporating a light pipe into the condenser design was also found to reduce noise in the image. Data are also presented on the use of air probes as height sensors for this demanding application (the Rayleigh depth of focus for a 0.6 N.A. lens at 248nm is 0.7μm). Data showing the sensitivity, stability and reproducibility of some different probe designs is shown. Finally, we present the design of the microstepper which is currently in the final stages of assembly.

Paper Details

Date Published: 25 July 1989
PDF: 12 pages
Proc. SPIE 1088, Optical/Laser Microlithography II, (25 July 1989); doi: 10.1117/12.953176
Show Author Affiliations
Chris Spence, U.C. Berkeley (United States)
William G. Oldham, U.C. Berkeley (United States)
William N. Partlo, U.C. Berkeley (United States)
John H. Bruning, GCA-Tropel (United States)
David A. Markle, Ultratech Stepper (United States)
Richard Hsu, U.C. Berkeley (United States)

Published in SPIE Proceedings Vol. 1088:
Optical/Laser Microlithography II
Burn Jeng Lin, Editor(s)

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