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Proceedings Paper

Excimer Laser Stepper for Sub-half Micron Lithography
Author(s): Akikazu Tanimoto; Akira Miyaji; Yutaka Ichihara; Tsunesaburoh Uemura; Issey Tanaka
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Paper Abstract

An excimer laser stepper having a flat image field was developed. Using a frequency stabilized, narrow band KrF 248nm laser (FWHM≈3μm), this stepper can print uniform patterns under 0.5 μm over a 15 mm square field. When the excimer laser output power is 2W, illumination intensity is more than 40 mW/cm2. Illumination uniformity is within ±2.5% over the field and exposure energy density is controlled within the precision of ±1.596, using an integrator sensor and a pulse number controller. A chromatic projection lens is adjusted so finely that aberrations are removed. In order to get imaging stability, a lens controller is used. An alignment system is off-axis, using He-Ne laser light spots and diffraction light detectors. By employing the EGA (Enhanced Global Alignment) method, overlay accuracy better than 0.18μm was obtained. Because the alignment detection light is insensitive to the resist, any types of resist may be used. The developed system has all the basic functions of a stepper. It can be used to improve DUV process and to fabricate sub-half micron devices in a laboratory.

Paper Details

Date Published: 25 July 1989
PDF: 7 pages
Proc. SPIE 1088, Optical/Laser Microlithography II, (25 July 1989); doi: 10.1117/12.953172
Show Author Affiliations
Akikazu Tanimoto, Nikon Corp. (Japan)
Akira Miyaji, Nikon Corp. (Japan)
Yutaka Ichihara, Nikon Corp. (Japan)
Tsunesaburoh Uemura, Nikon Corp. (Japan)
Issey Tanaka, Nikon Corp. (Japan)

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

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