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Proceedings Paper

Evaluating next-generation reticle demands on lithography equipment
Author(s): Morihisa Hoga; Masahiro Nei; Ryuichi Ebinuma
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Paper Abstract

Industry trends indicate that the next generation of exposure tool will be scanning steppers. Scanning steppers have a 25 mm by 33 mm field using 6 inch reticles. For device manufacturing, first generation 256M DRAM chips are roughly 12.5 mm by 25 mm, while 1G DRAM are expected to be 30 mm by 15 mm. As a result, a 25 mm by 33 mm field does not allow the exposure of two or more chips per shot. Therefore introduction of a larger mask is expected. To determine next generation reticle size standard, many factors have been investigated. First, an assumption was made that DRAM chip size trends will remain constant. Then, the throughput of scanning stepper was calculated with 6, 7, 8 and 9 inch reticles. The advantages were dependent on chip generation and device (memory or logic). Finally, a 9 inch reticle standard was chosen. Making the leap to a 9 inch reticle standard avoids the development time and costs of incremental changes in the standard. The thickness of a reticle is dependent upon reticle distortions, projection lens focus error. The deformation of the reticle has been simulated for the 0.25 to 0.5 inch thickness range. The final outcome of these simulations was that 9 mm (approximately 0.35 inch) was selected as the best thickness.

Paper Details

Date Published: 28 July 1997
PDF: 5 pages
Proc. SPIE 3096, Photomask and X-Ray Mask Technology IV, (28 July 1997); doi: 10.1117/12.277252
Show Author Affiliations
Morihisa Hoga, Hitachi, Ltd. (Japan)
Masahiro Nei, Nikon Corp. (Japan)
Ryuichi Ebinuma, Canon Inc. (Japan)

Published in SPIE Proceedings Vol. 3096:
Photomask and X-Ray Mask Technology IV
Naoaki Aizaki, Editor(s)

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