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Proceedings Paper

High-speed actinic EUV mask blank inspection with dark-field imaging
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Paper Abstract

We proposed an actinic (at-wavelength) EUV mask blank inspection method providing a printable phase-defect detection capability within the whole area of the mask blanks in an allowable inspection time. The inspection tool based on our method consists of optics for illuminating a mask blank with an EUV light, a mask blank stage, Schwarzschild optics for dark-field imaging, and a CCD camera. Phase-defect detection experiments were performed using a 10 Hz LPP source and with 0.2 NA imaging optics with the center obscuration NA of 0.1. Two-dimensional dark field image signal of 0.5 mmX0.5 mm area was captured by the CCD camera with 1M pixels and the phase-defects with the size down to 70 nm were successfully detected. In addition, a programmed phase defect and natural defect with 2 nm height were clearly detected. Inspection time including image capture and data processing for 0.5 mmX0.5 mm area was approximately 2 second. This is equivalent to an inspection time of 800 seconds/cm2. Inspection speed will increase by more than 10 times when combined with high power light source and high speed data acquisition. Although further optimization is needed, possibility of actinic inspection of EUV mask blanks within a practical inspection time has been demonstrated.

Paper Details

Date Published: 20 August 2004
PDF: 8 pages
Proc. SPIE 5446, Photomask and Next-Generation Lithography Mask Technology XI, (20 August 2004); doi: 10.1117/12.557814
Show Author Affiliations
Tsuneo Terasawa, Association of Super-Advanced Electronics Technologies (Japan)
Yoshihiro Tezuka, Association of Super-Advanced Electronics Technologies (Japan)
Masaaki Ito, Association of Super-Advanced Electronics Technologies (Japan)
Toshihisa Tomie, National Institute of Advanced Industrial Science and Techology (Japan)


Published in SPIE Proceedings Vol. 5446:
Photomask and Next-Generation Lithography Mask Technology XI
Hiroyoshi Tanabe, Editor(s)

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