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Proceedings Paper

Improving ASM stepper alignment accuracy by alignment signal intensity simulation
Author(s): Gerald Li; Sagar M. Pushpala; Bradley Bradford; Zezhong Peng; Mohan Gottipati
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Paper Abstract

As photolithography technology advances into submicron regime, the requirement for alignment accuracy also becomes much tighter. The alignment accuracy is a function of the strength of the alignment signal. Therefore, a detailed alignment signal intensity simulation for 0.8 micrometers EPROM poly-1 layer on ASM stepper was done based on the process of record in the fab to reduce misalignment and improve die yield. Oxide thickness variation did not have significant impact on the alignment signal intensity. However, poly-1 thickness was the most important parameter to affect optical alignments. The real alignment intensity data versus resist thickness on production wafers was collected and it showed good agreement with the simulated results. Similar results were obtained for ONO dielectric layer at a different fab.

Paper Details

Date Published: 4 August 1993
PDF: 9 pages
Proc. SPIE 1926, Integrated Circuit Metrology, Inspection, and Process Control VII, (4 August 1993); doi: 10.1117/12.148933
Show Author Affiliations
Gerald Li, National Semiconductor Corp. (United States)
Sagar M. Pushpala, National Semiconductor Corp. (United States)
Bradley Bradford, National Semiconductor Corp. (United States)
Zezhong Peng, Advanced Micro Devices, Inc. (United States)
Mohan Gottipati, Advanced Micro Devices, Inc. (United States)

Published in SPIE Proceedings Vol. 1926:
Integrated Circuit Metrology, Inspection, and Process Control VII
Michael T. Postek, Editor(s)

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