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Proceedings Paper

Exposure tool chuck flatness study and effects on lithography
Author(s): Moitreyee Mukherjee-Roy; Cher-Huan Tan; Yong Kwang Tan; Ganesh S. Samudra
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Paper Abstract

The flatness of the chuck on the stepper or scanner is critical to obtain good patterning performance especially in the sub quarter micron regime. In this study an attempt has been made to u7nderstand the flatness signature of the chuck by measuring the flatness of a super flat wafer in two different notch orientations and subtracting the signatures. If the chuck or the wafer were ideally flat then there would be no different in flatness signatures between the two orientations. However in practice difference was found as neither the chuck nor the wafer is perfectly flat. This difference could be used to obtain an understanding about the flatness signature on the scanner chuck itself. This signature could be used by equipment manufacturers as an additional method to measure chuck flatness so that only superior chucks are used for equipment that are being made for sub quarter micron lithography. The second part of this study consisted of finding out the effect of this flatness on the resulting CD on wafers. Wafers, with different flatness signatures, were exposed at different orientations and the CD variations were evaluated. All wafers showed improvements in the orientation of better flatness. For some wafers the improvements was significant but for others the result was close to the CD variation due to rework. This could be attributed to the inherent signatures on the wafers and how abrupt the change in flatness was. The wafer deformation factor was not analyzed for brevity as this would make the problem far more complex.

Paper Details

Date Published: 26 April 2001
PDF: 12 pages
Proc. SPIE 4404, Lithography for Semiconductor Manufacturing II, (26 April 2001); doi: 10.1117/12.425211
Show Author Affiliations
Moitreyee Mukherjee-Roy, Institute of Microelectronics (Singapore)
Cher-Huan Tan, Institute of Microelectronics (Singapore)
Yong Kwang Tan, National Univ. of Singapore (Singapore)
Ganesh S. Samudra, National Univ. of Singapore (Singapore)

Published in SPIE Proceedings Vol. 4404:
Lithography for Semiconductor Manufacturing II
Chris A. Mack; Tom Stevenson, Editor(s)

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