Zoom illumination system for use in photolithography

Abstract

The present invention provides an illumination system for varying the size of an illumination field incident to a scattering optical element. The illumination field is subsequently imaged to a reticle in a photolithographic process. The illumination system includes, in series along an optical axis of the illumination system, an optical source, a beam conditioner, a first optical integrator, a first or input collimating lens, a zoom array integrator (ZAI), a second or output collimating lens, the optical scattering element, a relay lens, and the reticle. The ZAI includes an assembly of fixed and moveable lens components arranged to vary the size of the illumination field throughout a zoom range of the ZAI while maintaining telecentric illumination at a substantially fixed numerical aperture. Illumination telecentricity and substantially fixed numerical apertures are maintained at both the scattering optical element and the reticle throughout the zoom range.

Dependencies are inferred from the claim text.