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Journal of Micro/Nanolithography, MEMS, and MOEMS

Novel in-situ focus monitor technology in attenuated phase shift mask under actual illumination conditions
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Paper Abstract

Focus monitor technology for attenuated phase shift masks under annular illumination has been developed for a in-line quality control. The focus monitor pattern on a reticle employs a pair of grouped lozenge-shaped opening patterns in the attenuated phase shifting region. Since the phase shifting angles of light passing through the first and second opening patterns are 90° and 0°, respectively, the best focus position for the first pattern shifts to that of the second pattern. Subtraction of the length of the patterns is a linear function of the actual focal position printed on the wafer. The linear function is insensitive to further mask phase error. Therefore, the effective focal position can be extracted by measuring that subtracted from the measured length. High resolution of 10 nm defocus was achieved using this technique.

Paper Details

Date Published: 1 April 2004
PDF: 9 pages
J. Micro/Nanolith. MEMS MOEMS 3(2) doi: 10.1117/1.1669541
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 3, Issue 2
Show Author Affiliations
Kyoko Izuha, Toshiba Corp. (Japan)
Masafumi Asano, Toshiba Corp. (Japan)
Tadahito Fujisawa, Toshiba Corp. (Japan)
Soichi Inoue, Toshiba Corp. (Japan)

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