A new process for accurate alignment using laser ablation technology

Hiroshi Ikegami; Kenji Kawano; Kazuhiko Ishigo; Tatsuhiko Higashiki; Nobuo Hayasaka; Naoto Yoshitaka; Hideaki Kashiwagi; Masayoshi Kobayashi; Yoichi Ogawa; Shinichi Ito

doi:10.1117/12.534907

28 May 2004 A new process for accurate alignment using laser ablation technology

Hiroshi Ikegami, Kenji Kawano, Kazuhiko Ishigo, Tatsuhiko Higashiki, Nobuo Hayasaka, Naoto Yoshitaka, Hideaki Kashiwagi , Masayoshi Kobayashi, Yoichi Ogawa, Shinichi Ito

Author Affiliations +

Proceedings Volume 5377, Optical Microlithography XVII; (2004) https://doi.org/10.1117/12.534907
Event: Microlithography 2004, 2004, Santa Clara, California, United States

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.

Citation Download Citation

Hiroshi Ikegami, Kenji Kawano, Kazuhiko Ishigo, Tatsuhiko Higashiki, Nobuo Hayasaka, Naoto Yoshitaka, Hideaki Kashiwagi , Masayoshi Kobayashi, Yoichi Ogawa, and Shinichi Ito "A new process for accurate alignment using laser ablation technology", Proc. SPIE 5377, Optical Microlithography XVII, (28 May 2004); https://doi.org/10.1117/12.534907

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