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Proceedings Paper

A new process for accurate alignment using laser ablation technology
Author(s): Hiroshi Ikegami; Kenji Kawano; Kazuhiko Ishigo; Tatsuhiko Higashiki; Nobuo Hayasaka; Naoto Yoshitaka; Hideaki Kashiwagi ; Masayoshi Kobayashi; Yoichi Ogawa; Shinichi Ito
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Paper Abstract

We have successfully achieved accurate alignment to remove stacked TiN/Ti/Al/TiN/Ti films on damascene W marks by using laser ablation technology. Because, the Al films deposited on the damascene W marks lead to poor quality of alignment accuracy due to the asymmetric topography of the deposited Al surfaces. In the case that the TiN/Ti film is not formed on the Al surface, high-density plasma is formed above the Al surface during laser irradiation. This plasma screens off the surface from laser irradiation. Therefore, it is difficult that the naked Al films are removed completely by the laser irradiation. From the results of thermal analysis of the TiN/Ti/Al films during laser irradiation, it is concluded that the irradiation fluence should be controlled as abrupt evaporation occurs at the Al surfaces without evaporation of the top TiN/Ti films. In this condition, the plasma cannot be formed above the TiN/Ti surfaces during laser irradiation. Therefore, the irradiation energy is absorbed efficiently in the TiN/Ti films and the TiN/Ti/Al/TiN/Ti films could be removed completely by laser irradiation. The global alignment random of wafer alignment after the TiN/Ti/Al/TiN/Ti film ablation on the W marks is equal to that of the ideal W marks before the Al film deposition. These results mean that the laser ablation is the most effective technology for locally removing thin metal films on alignment marks to achieve accurate alignment.

Paper Details

Date Published: 28 May 2004
PDF: 8 pages
Proc. SPIE 5377, Optical Microlithography XVII, (28 May 2004);
Show Author Affiliations
Hiroshi Ikegami, Toshiba Corp. (Japan)
Kenji Kawano, Toshiba Corp. (Japan)
Kazuhiko Ishigo, Toshiba Corp. (Japan)
Tatsuhiko Higashiki, Toshiba Corp. (Japan)
Nobuo Hayasaka, Toshiba Corp. (Japan)
Naoto Yoshitaka, Tokyo Electron Kyushu Ltd. (Japan)
Hideaki Kashiwagi , Tokyo Electron Kyushu Ltd. (Japan)
Masayoshi Kobayashi, Dainippon Screen Manufacturing Co., Ltd. (Japan)
Yoichi Ogawa, Dainippon Screen Manufacturing Co., Ltd. (Japan)
Shinichi Ito, Toshiba Corp. (Japan)

Published in SPIE Proceedings Vol. 5377:
Optical Microlithography XVII
Bruce W. Smith, Editor(s)

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