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

Tsuneo Terasawa; Yoshihiro Tezuka; Masaaki Ito; Toshihisa Tomie

doi:10.1117/12.557814

20 August 2004 High-speed actinic EUV mask blank inspection with dark-field imaging

Tsuneo Terasawa, Yoshihiro Tezuka, Masaaki Ito, Toshihisa Tomie

Proceedings Volume 5446, Photomask and Next-Generation Lithography Mask Technology XI; (2004) https://doi.org/10.1117/12.557814
Event: Photomask and Next Generation Lithography Mask Technology XI, 2004, Yokohama, Japan

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.

Citation Download Citation

Tsuneo Terasawa, Yoshihiro Tezuka, Masaaki Ito, and Toshihisa Tomie "High-speed actinic EUV mask blank inspection with dark-field imaging", Proc. SPIE 5446, Photomask and Next-Generation Lithography Mask Technology XI, (20 August 2004); https://doi.org/10.1117/12.557814

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available