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7 December 1994 Chromium-based attenuated phase shifter for DUV exposure
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An attenuated phase shift mask (APSM) for DUV exposure using a chromium fluoride film as an embedded phase shifter is developed. The chromium fluoride film is deposited by the conventional dc reactive sputtering process using gases such as CF4 or SF6 as the fluorine source. This film can be dry-etched by the chlorine chemistry, so that an etch into the quartz plate, which causes phase error, is negligible and high accuracy phase shift control can be achieved. Furthermore, this film shows a transmission of ca. 15% at 248 nm as a single- layered embedded shifter deposited on the quartz plate (100% for air), and therefore, in combination with an opaque chrome layer, various transmissions up to ca. 8% can be obtained without changing the shifter material. Promising properties as a practical shifter material are confirmed, and an exposure test on 2.5 micrometers and 3.0 micrometers hole patterns, using an APSM with a trilayer shifter, where an opaque chrome film is sandwiched by two chromium fluoride films, shows that the focus latitude can be extended compared with conventional chrome masks.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hiroshi Mohri, Masahiro Takahashi, Koichi Mikami, Hiroyuki Miyashita, Naoya Hayashi, and Hisatake Sano "Chromium-based attenuated phase shifter for DUV exposure", Proc. SPIE 2322, 14th Annual BACUS Symposium on Photomask Technology and Management, (7 December 1994);

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