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Proceedings Paper

CD uniformity of photomasks written with high-voltage variable-shaped e beam
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Paper Abstract

The critical dimension uniformity required in the fabrication of photomasks for 1 gigabit DRAMs will be more stringent that 20 nm in terms of 3 sigma. High-voltage variable-shaped e-beam (VSB) writing is advantageous because of its high resolution, linewidth stability, and throughput performance. However, stitching errors in VSB writing have been a critical problem in the fabrication of advanced photomasks. In this paper, an improved method to calibrate the size of a VSB shot and reduce shot stitching errors is proposed. The accuracy of the calibration method depends on that of the linewidth measurement system, and shot-size calibration with an accuracy of +/- 10 nm can be achieved using existing measurement systems. The positioning accuracy of VSB shots was enhanced by a multiple pass exposure scheme. With these procedures applied to a 50 kV VSB system, the linewidth variation of a photomask in a local area such as a square region of 200 micrometers X 200 micrometers was reduced to less than 20 nm.

Paper Details

Date Published: 27 May 1996
PDF: 10 pages
Proc. SPIE 2723, Electron-Beam, X-Ray, EUV, and Ion-Beam Submicrometer Lithographies for Manufacturing VI, (27 May 1996); doi: 10.1117/12.240462
Show Author Affiliations
Noriaki Nakayamada, Toshiba USLI Research Lab. (Japan)
Shigehiro Hara, Toshiba USLI Research Lab. (Japan)
Toshiyuki Magoshi, Toshiba USLI Research Lab. (Japan)
Hideaki Sakurai, Toshiba USLI Research Lab. (Japan)
Takayuki Abe, Toshiba USLI Research Lab. (Japan)
Iwao Higashikawa, Toshiba USLI Research Lab. (Japan)


Published in SPIE Proceedings Vol. 2723:
Electron-Beam, X-Ray, EUV, and Ion-Beam Submicrometer Lithographies for Manufacturing VI
David E. Seeger, Editor(s)

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