Mr. Fumihiro Koba Profile

Fumihiro Koba

Researcher at SELETE

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Publications (8)

Proceedings Article | 2 April 2007 Paper

Correlation between etching and optical properties of organic films for multilayer resist

E. Soda, F. Koba, S. Kondo, S. Ogawa, S. Saito

Proceedings Volume 6519, 65192P (2007) https://doi.org/10.1117/12.710788

KEYWORDS: Etching, Refractive index, Critical dimension metrology, FT-IR spectroscopy, Silicon, Scanning electron microscopy, Semiconducting wafers, Optical properties, Polymers, Electron beam lithography

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Proceedings Article | 24 March 2006 Paper

Tri-layer resists process for fabricating 45-nm L&S patterns by EPL

Fumihiro Koba, Kazuyuki Matsumaro, Eiichi Soda, Tadayoshi Watanabe, Yoshihisa Matsubara, Hiroshi Arimoto, Tasuku Matsumiya, Daisuke Kawana, Naoki Yamashita, Yasushi Fujii, Katsumi Ohmori, Mitsuru Sato, Takahiro Kozawa, Seiichi Tagawa

Proceedings Volume 6151, 615127 (2006) https://doi.org/10.1117/12.655976

KEYWORDS: Photoresist processing, Failure analysis, Etching, Back end of line, Semiconducting wafers, Critical dimension metrology, Electron beam lithography, Lithography, Extreme ultraviolet lithography, Photomasks

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In this study, we have demonstrated a resist process to fabricate sub 45-nm lines and spaces (L&S) patterns (1:1) by using electron projection lithography (EPL) for a back-end-of-line (BEOL) process for 45-nm technology node. As a starting point we tried to fabricate sub 45-nm L&S (1:1) patterns using a conventional EPL single-layer resist process. There, the resolution of the EPL resist patterns turned out to be limited to 70 nm L&S (1:1) with aspect ratio (AR) of 3.3 which was caused by pattern collapse during the drying step in resist develop process. It has been common knowledge that pattern collapse of this type could be prevented by reducing the surface tension of the rinse-liquid and by decreasing the AR of the resist patterns. Therefore, we first applied a surfactant rinse to a single-layer resist process that could control the pattern collapse by its reduced surface tension. In this experiment, we used the ArF resist instead of the EPL resist because the surfactant that we were able to obtain was the one optimized to the ArF resist materials. From the results of ArF resist experiments, it was guessed that it was difficult for the EPL resist to obtain the L&S patterns with AR of 3.5 or more even if we used the surfactant optimized to the EPL resist. And we found that it was considerably difficult to form 45-nm L&S patterns with AR of 5.1 that was our target. Next, we evaluated a EPL tri-layer resist process to prevent pattern collapse by decreasing the AR of the resist patterns. Because in a tri-layer resist process the purpose of the top-layer resist is to transfer pattern to the middle-layer, a thinner top-layer resist was selected. By using the tri-layer resist process we were able to control the resist pattern collapse and thus were successful in achieving 40-nm L/S (1:1) top-layer resist patterns with AR of 2.3. The process also gave us 40-nm L&S (1:1) patterns after low-k film etching. And moreover, using our tri-layer resist process we were able to fabricate a wiring device with Cu/low-k. Although it was our first attempt, the process resulted in a high yield of 70 % for a 60-nm (1:1) wiring device. As a part of our study we conducted failure analysis of the results of our experiment. We found that the failures were located at the edge of the wafer and might originate in the bottom-layer pattern collapse. We thought that the wiring yield could be increased by control the bottom-layer pattern collapse. These findings indicated that our tri-layer resist process had a high applicability for device fabrication in BEOL.

Proceedings Article | 23 March 2006 Paper

Resolution improvement of EPL stencil mask using thin membrane

Hiroshi Sugimura, Hideyuki Eguchi, Masashi Norimoto, Yoshiyuki Negishi, Isao Yonekura, Kojiro Ito, Akira Tamura, Fumihiro Koba, Hiroshi Arimoto

Proceedings Volume 6151, 61511F (2006) https://doi.org/10.1117/12.655425

KEYWORDS: Photomasks, Reactive ion etching, Etching, Semiconducting wafers, Scattering, Mask making, Electron beam lithography, Silicon, Image resolution, Optical lithography

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Proceedings Article | 6 May 2005 Paper

EPL performance in 65-nm node metallization technology and beyond

F. Koba, T. Tsuchida, H. Sakaue, K. Koike, J. Yamamoto, N. Iriki, H. Yamashita, S. Kageyama, T. Nasuno, E. Soda, K. Takeda, H. Kobayashi, F. Shoji, H. Okamura, Y. Matsubara, H. Arimoto

Proceedings Volume 5751, (2005) https://doi.org/10.1117/12.599257

KEYWORDS: Metals, Transmission electron microscopy, Lithography, Scanners, Copper, Scanning electron microscopy, Resistance, Electron beam lithography, Overlay metrology, Chemical mechanical planarization

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Proceedings Article | 20 May 2004 Paper

Preliminary results of EB stepper in the application of 65-nm process

Hiroshi Takenaka, Kaoru Koike, Takahiro Tsuchida, Fumihiro Koba, Hiroshi Sakaue, Masaki Yamabe

Proceedings Volume 5374, (2004) https://doi.org/10.1117/12.534875

KEYWORDS: Metals, Resistance, Overlay metrology, Lithography, Photomasks, Distortion, Copper, Photography, Electron beam lithography, Optical lithography

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Proceedings Article | 20 May 2004 Paper

Performance and stability of electron projection lithography tool

Hiroshi Sakaue, Kaoru Koike, Hiroshi Takenaka, Takahiro Tsuchida, Fumihiro Koba, Masaki Yamabe

Proceedings Volume 5374, (2004) https://doi.org/10.1117/12.534892

KEYWORDS: Distortion, Reticles, Semiconducting wafers, Photomasks, Optical alignment, Overlay metrology, Electron beam lithography, Projection lithography, Lithography, Data corrections

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Proceedings Article | 20 May 2004 Paper

Design rule of hole-layer for electron projection lithography

Kaoru Koike, Hiroshi Sakaue, Hiroshi Takenaka, Fumihiro Koba, Takahiro Tsuchida, Masaki Yamabe

Proceedings Volume 5374, (2004) https://doi.org/10.1117/12.534868

KEYWORDS: Photomasks, Electron beam lithography, Projection lithography, Lithography, Finite element methods, Semiconducting wafers, Critical dimension metrology, Optical lithography, Semiconductors, Optical simulations

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Proceedings Article | 21 July 2000 Paper

Optimization of PHS-based chemically amplified negative resist for 100-kV electron-beam projection lithography (EPL)

Mami Miyasaka, Kenichi Tokunaga, Fumihiro Koba, Hiroshi Yamashita, Ken Nakajima, Hiroshi Nozue

Proceedings Volume 3997, (2000) https://doi.org/10.1117/12.390070

KEYWORDS: Quantum efficiency, Projection lithography, Lithography, Electron beam direct write lithography, Electron beam lithography, Electron beams, Photomasks, Scanning electron microscopy, Molecules, Chemical analysis

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Showing 5 of 8 publications

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