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Proceedings Paper

EB-X1: an accurate x-ray mask writer using a variable-shaped beam
Author(s): Nobuo Shimazu; Takashi Watanabe; Tetsuo Morosawa; Hirofumi Morita; Youichi Kuriyama; Tatsuya Kunioka
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Paper Abstract

The EB-X1 is an accurate X-ray mask writer with high-throughput that was developed by modifying one of our EB60 variable-shaped E-beam systems. For high resolution, we developed an electron optical system whose 50-nm beam edge sharpness, a 15 A/cm2 beam current density, and 1.0-micrometers X 0.5-micrometers maximum beam size with an acceleration voltage under 30 keV were determined by proximity-effect Monte Carlo simulation. We adopt a three-pronged approach for accurate pattern placement. First, we improve the beam positioning resolution from 20 nm to 5 nm. Because we suppress mechanical vibration, we can attain a 11-nm standard mark detection accuracy, resulting in a 20-nm compensation accuracy in the beam deflection distortion and a 25-nm field stitching accuracy. Second, our new column with its short beam-path and demagnification image of variable-shaped beam optics can attain a beam position stability within 30 nm over two hours. Finally, the use of an electrostatic chuck to firmly hold the mask-substrate with little holding- deformation and large heat transmission reduces mask-substrate deformation to 23 nm during pattern writing. Experiments confirm the EB-X1 can write a 0.2-micrometers minimum-feature sized pattern, has a pattern placement accuracy of 50 nm (3 (sigma) ) and a high throughput approximately ten times higher than that of a conventional point-beam exposure system. Using optimized correction coefficients for a specific layer, an average pattern placement accuracy of 33 nm (3 (sigma) ) can be achieved. The EB-X1 is now being used in the X-ray mask fabrication process line at NTT LSI Laboratories.

Paper Details

Date Published: 3 November 1994
PDF: 9 pages
Proc. SPIE 2254, Photomask and X-Ray Mask Technology, (3 November 1994); doi: 10.1117/12.191924
Show Author Affiliations
Nobuo Shimazu, NTT LSI Labs. (Japan)
Takashi Watanabe, NTT LSI Labs. (Japan)
Tetsuo Morosawa, NTT LSI Labs. (Japan)
Hirofumi Morita, NTT LSI Labs. (Japan)
Youichi Kuriyama, NTT LSI Labs. (Japan)
Tatsuya Kunioka, NTT LSI Labs. (Japan)

Published in SPIE Proceedings Vol. 2254:
Photomask and X-Ray Mask Technology
Hideo Yoshihara, Editor(s)

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