Development of Tool for Contamination Layer Thickness Measurement Using High Power Extreme Ultraviolet Light and in Situ Ellipsometer

• Takeo Watanabe

• Yukiko Kikuchi

• Toshiya Takahashi

• Kazuhiro Katayama

• Isamu Takagi

• Norihiko Sugie

• Hiroyuki Tanaka

• Eishi Shiobara

• Soichi Inoue

• Tetsuo Harada

• Hiroo Kinoshita

Abstract

Extreme ultraviolet (EUV) lithographic exposure is performed in a vacuum environment. The Mo/Si multilayers used as imaging optics and a mask can be contaminated by carbon, which is originally an outgassing species of the hydrocarbons that decompose from the resist materials during EUV exposure. This carbon contamination reduces the total reflectivity of the imaging optics and mask, and affects the lithographic performance, including the throughput and resist pattern replication resolution. This contamination should be reduced to maintain the lithographic performance; thus, the relationship between the carbon contamination and the outgassing species should be clarified. We therefore developed a novel tool for in situ contamination layer thickness evaluation. The distinctive features of this tool are as follows: 1) exposure using a total power of in-band EUV light (267 mW/cm 2 ) that is as high as that required for high-volume manufacturing (>100 mW/cm 2 ), 2) the visible light beam of the in situ spectroscopic ellipsometry is focused on the Mo/Si multilayer witness sample to obtain the detection limit for measured thickness and that the limit was found to be 0.03 nm, and 3) the witness and 8-in. resist wafer sample stages have extremely low outgassing characteristics. Using this tool, a starting adhesion point was observed and the carbon contamination layer thickness was evaluated during the resist exposure. For 90 min resist exposure, no contamination adhered onto the Mo/Si witness sample until the exposure time reached 25 min, and after which, the contamination started to adhere to the witness sample.

Journal

• Japanese Journal of Applied Physics

  Japanese Journal of Applied Physics 52 (5R), 056701-, 2013-04-30

  IOP Publishing

Keywords

• General Physics and Astronomy
• General Engineering

Details

• CRID: 1360566399840236288
• NII Article ID: 210000142182
• DOI: 10.7567/jjap.52.056701
• ISSN: 13474065
• ISSN: 00214922
• ISSN: http://id.crossref.org/issn/13474065
• Web Site: https://iopscience.iop.org/article/10.7567/JJAP.52.056701
• Web Site: https://iopscience.iop.org/article/10.7567/JJAP.52.056701/pdf
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