Improving ASM stepper alignment accuracy by alignment signal intensity simulation

Gerald Li; Sagar M. Pushpala; Bradley Bradford; Zezhong Peng; Mohan Gottipati

doi:10.1117/12.148933

4 August 1993 Improving ASM stepper alignment accuracy by alignment signal intensity simulation

Gerald Li, Sagar M. Pushpala, Bradley Bradford, Zezhong Peng, Mohan Gottipati

Proceedings Volume 1926, Integrated Circuit Metrology, Inspection, and Process Control VII; (1993) https://doi.org/10.1117/12.148933
Event: SPIE'S 1993 Symposium on Microlithography, 1993, San Jose, CA, United States

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.

Citation Download Citation

Gerald Li, Sagar M. Pushpala, Bradley Bradford, Zezhong Peng, and Mohan Gottipati "Improving ASM stepper alignment accuracy by alignment signal intensity simulation", Proc. SPIE 1926, Integrated Circuit Metrology, Inspection, and Process Control VII, (4 August 1993); https://doi.org/10.1117/12.148933

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