Zernike phase contrast microscope for EUV mask inspection

Yow-Gwo Wang; Ryan Miyakawa; Andrew Neureuther; Patrick Naulleau

doi:10.1117/12.2048180

17 April 2014 Zernike phase contrast microscope for EUV mask inspection

Yow-Gwo Wang, Ryan Miyakawa, Andrew Neureuther, Patrick Naulleau

Proceedings Volume 9048, Extreme Ultraviolet (EUV) Lithography V; 904810 (2014) https://doi.org/10.1117/12.2048180
Event: SPIE Advanced Lithography, 2014, San Jose, California, United States

Abstract

In this paper, we address a new inspection method which provides in-focus inspection capability and higher defect sensitivity compared with conventional mask inspection methods. In the Zernike phase contrast microscope, an added phase shift to background wave combines with the phase of bump and pit defects to achieve higher contrast at focus. If we use a centralized apodization to half the lens radius to further reduce the intensity of the phase-shifted background wave, the signal strength can be improved up to 6-fold of its original value. Simulation results further show that this apodization for a typical EUV mask power spectral density results in the noise decreasing in absolute level similar to the clear field reference signal. Thus large improvements in signal to noise ratios are possible with the Zernike phase contrast microscope type systems for EUV mask inspection applications.

Citation Download Citation

Yow-Gwo Wang, Ryan Miyakawa, Andrew Neureuther, and Patrick Naulleau "Zernike phase contrast microscope for EUV mask inspection", Proc. SPIE 9048, Extreme Ultraviolet (EUV) Lithography V, 904810 (17 April 2014); https://doi.org/10.1117/12.2048180

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