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Proceedings Paper

Interferometric-probe monitors for self-diagnostics of phase-shifting mask performance
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Paper Abstract

A pattern and interferometric-probe technique is introduced for self-testing the effective phase-depth, transmission, and edge effects of shifted regions of a phase-shifting mask (PSM). Both manufacturing error and image intensity imbalance between regions of differing phase necessitate an accurate, feature-dependent measurement. Through utilizing the coherent spillover (proximity effect) from a phase-etched pattern onto a phased-probe, any phase or transmission error is converted into a signal, measurable on either an AIMS tool or observed as an exposed probe in printed resist. The orthogonality of phase and transmission error allows amplification of each separately with either a 0° or 90° probe. The intensity change is a linear function of phase or transmission error and depends only on the size of the pattern and probe used. For example, a simple target of radius 3.1 λ/NA responds with 1% of the clear field intensity per degree of phase error. Simulation studies of several embodiments are shown as well as a mathematical theory describing the monitor's behavior. Target sensitivity is greater than existing image-plane analysis techniques for most feature types, to include phase trenches and contact arrays, and does not require through-focus analysis. Functionality is only slightly affected by lens aberrations and probe-manufacturing errors. Mask manufacturing is relatively simple and can be placed on a special test mask or interspersed in a production mask layout.

Paper Details

Date Published: 17 December 2003
PDF: 7 pages
Proc. SPIE 5256, 23rd Annual BACUS Symposium on Photomask Technology, (17 December 2003); doi: 10.1117/12.518273
Show Author Affiliations
Gregory R. McIntyre, Univ. of California/Berkeley (United States)
Andrew Neureuther, Univ. of California/Berkeley (United States)

Published in SPIE Proceedings Vol. 5256:
23rd Annual BACUS Symposium on Photomask Technology
Kurt R. Kimmel; Wolfgang Staud, Editor(s)

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