Paper
22 January 2001 Impact of alternating phase-shift mask quality on 100-nm gate lithography
Tomohiko Yamamoto, Naoyuki Ishiwata, Satoru Asai
Author Affiliations +
Abstract
A dual exposure method with an alternating phase shift mask has been proposed for using KrF laser lithography to fabricate 100 nm gate patterns for logic devices. Fine and uniform patterns can be formed and so this process is considered very advantageous in terms of the formation of gate for logic devices. Several factors determine the lithographic performance of the alternating phase shift mask: phase accuracy, amount of undercutting, quartz and chromium defects, and so on. It is thought that these factors need to be strictly controlled. We thus investigated the impact of errors in the fabrication of alternating phase shift masks to determine the quality required for the dual exposure method, focusing on three factors: phase accuracy, amount of undercutting, and defects. A phase error causes CD variation and lateral shift in the defocused condition. Unsuitable undercutting causes lateral shift at the best focus. Shifter and chromium defects cause CD variation and distortion of the gate patterns. Our experimental results showed that these factors do not need to be strictly controlled. We thus propose a fabrication process for alternating phase shift masks to be used in the dual exposure method. Keywords: Alternating phase shift mask, dual exposure, phase accuracy, undercutting, defect
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Tomohiko Yamamoto, Naoyuki Ishiwata, and Satoru Asai "Impact of alternating phase-shift mask quality on 100-nm gate lithography", Proc. SPIE 4186, 20th Annual BACUS Symposium on Photomask Technology, (22 January 2001); https://doi.org/10.1117/12.410719
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KEYWORDS
Photomasks

Chromium

Phase shifts

Critical dimension metrology

Lithography

Bridges

Quartz

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