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Proceedings Paper

Importance of wafer flatness for CMP and lithography
Author(s): Yuan Zhang; Lucian Wagner; Peter Golbutsov
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Paper Abstract

Chemical mechanical planarization (CMP) is aimed at planarizing wafer surfaces in order to meet the tightening depth-of-focus requirements for advanced lithography. A simple method will be introduced which uses the site flatness requirement from the 1994 National Technology Roadmap for Semiconductors as a criterion to qualify post- CMP wafer flatness. Wafer dimensional data measured on a capacitance gauge were converted into local flatness with different site sizes according to the roadmap. The resulting site flatness was then subtracted from the required flatness threshold. The results suggest that current CMP technology improves wafer flatness from a 0.35 micrometers technology point of view. As the design rules shrink, however, more than half of the sites do not meet the 0.25 micrometers lithographic requirements even though there are flatness improvements due to CMP. Thus, much flatter wafers and more effective planarization technologies are needed to meet the challenges of next device generations.

Paper Details

Date Published: 7 July 1997
PDF: 4 pages
Proc. SPIE 3050, Metrology, Inspection, and Process Control for Microlithography XI, (7 July 1997); doi: 10.1117/12.275916
Show Author Affiliations
Yuan Zhang, ADE Corp. (United States)
Lucian Wagner, ADE Corp. (United States)
Peter Golbutsov, ADE Corp. (United States)

Published in SPIE Proceedings Vol. 3050:
Metrology, Inspection, and Process Control for Microlithography XI
Susan K. Jones, Editor(s)

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