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14 September 2001 Applications of a grating shearing interferometer at 157 nm
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Progress along the path towards smaller semiconductor feature sizes continually presents new challenges. 157nm technology is a promising new step along this path. The major challenges encountered to date include environmental purging for high transmission and beam alignment in a purged environment at this short wavelength. We present a simple shearing interferometer consisting of two Ronchi phase gratings in series, used on axis. The common path set-up and zero optical path difference between the interfering diffraction orders makes this device both robust and easy to align. Ease of alignment is an added benefit when working remotely in a purged environment with low light levels. If one grating is shifted relative to the other, a phase shift is introduced and phase measurement techniques can be employed for high accuracy characterization of the incident wavefront. Set-ups, measurements and characterization of wavefronts and spatial-coherence at 157nm made with this device are presented.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Horst Schreiber, Paul G. Dewa, Michael M. Dunn, Richard Hordin, Stephen K. Mack, Bryan D. Statt, and Paul Jay Tompkins "Applications of a grating shearing interferometer at 157 nm", Proc. SPIE 4346, Optical Microlithography XIV, (14 September 2001);

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