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Proceedings Paper

A novel post exposure bake technique to improve CD uniformity over product wafers
Author(s): Tomoyuki Takeishi; K. Hayasaki; Tsuyoshi Shibata
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Paper Abstract

The impact of wafer warpage on critical dimension (CD) control is getting larger in ArF lithography. The product wafers with stacked films are warped due to the stress caused by the difference in the film stack structure between the top side and the back side of the wafers. A typical warpage of the product wafers is of convex shape, and the amount of the warpage is larger than 50 μm for 200mm wafer. On the other hand, proximity bake method is widely used in the Post Exposure Bake (PEB). When the warped wafer is placed on the hot plate, the gap between the wafer and the hot plate varies across the wafer. That is, the temperature of the wafer center is lower than that of wafer edge. Such a temperature variation affects CD uniformity within wafer. In particular the fact is obvious in ArF chemical amplified resist because PEB sensitivity of ArF resist is larger than 5nm/degree. In this study we optimize PEB zone temperature within wafer to suit the wafer warpage. This method is based on controlling zone temperature of the PEB hot plate with concentrically divided heaters. We carry out that the CD uniformity for the warped wafer is improved by 70% compared with the conventional process.

Paper Details

Date Published: 4 May 2005
PDF: 8 pages
Proc. SPIE 5753, Advances in Resist Technology and Processing XXII, (4 May 2005); doi: 10.1117/12.599192
Show Author Affiliations
Tomoyuki Takeishi, Toshiba Corp. (Japan)
K. Hayasaki, Toshiba Corp. (Japan)
Tsuyoshi Shibata, Toshiba Corp. (Japan)

Published in SPIE Proceedings Vol. 5753:
Advances in Resist Technology and Processing XXII
John L. Sturtevant, Editor(s)

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