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Proceedings Paper

High-optical-density photomasks for large exposure applications
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Paper Abstract

Microlithography applications such as advanced packaging, micromachining and thin film head (TFH) production frequently require the use of thick photoresists and large exposure doses for successful pattern transfer onto substrates. When thick negative acting photoresists are used, exposures as high as 5000mJ/cm2 may be required to maintain the pre-exposure photoresist thickness after develop. In this study, light transmission through photomasks with standard (OD3) and high-density (OD4) Cr films was measured through the ultraviolet spectrum to determine leakage thresholds and evaluate the risk of unwanted exposure with highly sensitive photoresists. Because the higher OD photomasks are the result of an increase in Cr film thickness, photomask process differences, resolution capability and Critical Dimension (CD) uniformity issues were also evaluated. The thicker Cr film could also affect pattern transfer to the wafer. Therefore, resolution and CD uniformity were compared on wafers patterned from both OD3 and OD4 Cr reticles.

Paper Details

Date Published: 22 January 2001
PDF: 12 pages
Proc. SPIE 4186, 20th Annual BACUS Symposium on Photomask Technology, (22 January 2001); doi: 10.1117/12.410770
Show Author Affiliations
Dan L. Schurz, Ultratech Stepper, Inc. (United States)
Warren W. Flack, Ultratech Stepper, Inc. (United States)
Makoto Nakamura, Ultratech Stepper, Inc. (United States)

Published in SPIE Proceedings Vol. 4186:
20th Annual BACUS Symposium on Photomask Technology
Brian J. Grenon; Giang T. Dao, Editor(s)

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