12 February 1997 Novel alternating phase-shift mask with improved phase accuracy
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Abstract
We developed an alternating phase shift mask that offers a sufficient phase accuracy for manufacturing sub-0.18 micrometer devices with 248 nm deep-UV lithography. This mask has a Cr/spin-on-glass/quartz structure. Our mask fabrication process utilizes some new techniques which include the use of a SOG shifter with extra thickness, a two step SOG etching, and an additional wet etchign process for phase adjustment. Our process showed a good performance, and a phase controllability of 180 plus or minus 0.7 degrees was achieved. Phase uniformity was less than 3 degrees over a 100 mm square area. It was nearly equal to the uniformity of the SOG thickness. These results prove that the additional etching process is very effective at improving phase accuracy.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Naoyuki Ishiwata, Takema Kobayashi, Satoru Asai, Isamu Hanyu, "Novel alternating phase-shift mask with improved phase accuracy", Proc. SPIE 3236, 17th Annual BACUS Symposium on Photomask Technology and Management, (12 February 1997); doi: 10.1117/12.301196; https://doi.org/10.1117/12.301196
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