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Proceedings Paper

New approach to phase metrology for manufacturing 248-nm lithography-based embedded attenuated phase-shifting mask
Author(s): Giang T. Dao; Gang Liu; Alan Snyder; Jeff N. Farnsworth
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Paper Abstract

One of major benefits of attenuated phase-shifting mask, also called half-tone mask, over binary mask is the increase in depth-of-focus. This improvement, however, will be drastically reduced if phase error over the entire reticle is excessive. It is well known that phase error causes focal shift at the wafer level, leading to loss of useful depth of focus. Therefore, controlling phase error is critical in achieving good lithographic performance of embedded attenuated phase-shifting mask (EPSM). Most recently there are newly developed tools that can be used to measure phase at 248 nm wavelength. However, these tools can't measure phase of actual device patterns such as 0.25 xm contact holes due to beam size. This paper will present a new approach that directly measures focal shift of actual device patterns using Aerial Image Measurement. We have successfully utilized this approach in our development of EPSM reticle fabrication process leading to a focal shift uniformity of ≤ 0.2 μm over the entire 6" EPSM reticle. This new approach is also being used as a quality control tool in our mask fabrication process. New metrology pattern design will be described. Measurement accuracy and repeatability and data analysis methodology will be discussed.

Paper Details

Date Published: 24 July 1996
PDF: 12 pages
Proc. SPIE 2793, Photomask and X-Ray Mask Technology III, (24 July 1996); doi: 10.1117/12.245240
Show Author Affiliations
Giang T. Dao, Intel Corp. (United States)
Gang Liu, Intel Corp. (United States)
Alan Snyder, Intel Corp. (United States)
Jeff N. Farnsworth, Intel Corp. (United States)


Published in SPIE Proceedings Vol. 2793:
Photomask and X-Ray Mask Technology III
Hideo Yoshihara, Editor(s)

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