Improvements in CaF2 material properties for next-generation microlithography applications

Jeffrey T. Kohli; Qiao Li; William R. Rosch

doi:10.1117/12.534578

28 May 2004 Improvements in CaF₂ material properties for next-generation microlithography applications

Jeffrey T. Kohli, Qiao Li, William R. Rosch

Proceedings Volume 5377, Optical Microlithography XVII; (2004) https://doi.org/10.1117/12.534578
Event: Microlithography 2004, 2004, Santa Clara, California, United States

Abstract

The key requirements of CaF₂ lens blanks are transmission, birefringence and optical homogeneity. While it is obvious that high transmission and resistance to fluence- and time-dependent darkening is critical, the subtleties of single crystals, compared to isotropic glasses, play an important role in the implementation of CaF₂ in microlithography steppers. The existence of intrinsic birefringence has caused stepper manufacturers to employ various crystallographic orientations in their lens designs. This fact means that crystal growth and annealing processes must be optimized accordingly. Small-scale defects, known as dislocations and sub-grain mis-orientation, manifest themselves as larger-scale defects known as slip and mosaic. These imperfections may impact birefringence and a critical homogeneity parameter known as residual rms. Residual rms is directly related to the concentration of asymmetric defects in CaF₂ crystals, such as those aforementioned. In the present paper, the author will report on progress made at Corning to meet the stringent requirements of both 193nm and 157nm systems.

Citation Download Citation

Jeffrey T. Kohli, Qiao Li, and William R. Rosch "Improvements in CaF₂ material properties for next-generation microlithography applications", Proc. SPIE 5377, Optical Microlithography XVII, (28 May 2004); https://doi.org/10.1117/12.534578

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