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Proceedings Paper

Low Distortion X-Ray Mask With W-Ti Absorber
Author(s): Nobuyuki Yoshioka; Susumu Takeuchi; Hiroaki Morirnoto; Yaichiro Watakabe
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Paper Abstract

The performance of W-Ti alloy as an x-ray mask absorber material was investigated in order to obtain a low distortion x-ray mask. The W-Ti films were deposited by sputtering the W-Ti (1wt% Ti content) target using Ar + N2 gas with a DC magnetron sputtering system. It was found that the internal stress and the density in the W-Ti films strongly depend on the gas pressure and N2 content of the Ar + N2 sputtering gas. The internal stress of W-Ti films deposited using Ar + N2 of 30% N2 content decreased with increasing gas pressure from a very large compressive stress, and became small in the region of above 2 Pa. The stress in W-Ti films deposited in this pressure region was very small (0.5-2.0 x 107 N/m2). This value is fully satisfactory for an x-ray mask absorber. The density of the low-stress W-Ti film is also satisfactory for the x-ray mask absorber. The etching properties of W-Ti film were evaluated for CF4 + 02 gas plasma. It was found that the etching rate becomes the maximum (1500 Å/min.) at the 02 content of 15-20%. In order to demonstrate the accuracy of the W-Ti x-ray mask, the full exposure mask (BN/Polyimide membrane) and the stepper mask (SiN/Polyimide membrane) were fabricated. As a result, x-ray masks with very small distortion (less than 0.1pm for 15 x 15mm field ) were obtained. It is concluded that the low distortion W-Ti mask is practical for use in submicron VLSI fabrication.

Paper Details

Date Published: 14 June 1988
PDF: 7 pages
Proc. SPIE 0923, Electron-Beam, X-Ray, and Ion Beam Technology: Submicrometer Lithographies VII, (14 June 1988); doi: 10.1117/12.945626
Show Author Affiliations
Nobuyuki Yoshioka, Mitsubishi Electric Corporation (Japan)
Susumu Takeuchi, Mitsubishi Electric Corporation (Japan)
Hiroaki Morirnoto, Mitsubishi Electric Corporation (Japan)
Yaichiro Watakabe, Mitsubishi Electric Corporation (Japan)

Published in SPIE Proceedings Vol. 0923:
Electron-Beam, X-Ray, and Ion Beam Technology: Submicrometer Lithographies VII
Arnold W. Yanof, Editor(s)

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