DEPTH OF FOCUS ENHANCEMENT METHOD AND ITS DEVICE USING OPTICAL COMPONENT MADE BIREFRINGENT MATRIAL LITHOGRAPHT TOOLS

摘要

PURPOSE: A method for extending depth of focus of an optical system for lithographic equipment using transmission-type optical parts made of a double refraction material is provided to extend a range of an image in a direction of an optical axis, by making the image located in different positions have a predetermined interval in an optical axial direction depending on a polarization component of illumination light. CONSTITUTION: An optical system uses transmission-type double refraction optical parts(210) made of a double refraction material or a double refraction optical unit composed of the optical parts. An image by the double refraction optical unit(200) is focused in different positions and in a direction of an optical axis of the optical system to extend depth of focus, depending on a polarization component of illumination light(20).