IMPROVEMENT IN LITHOGRAPHY SYSTEM AND DEFINITION OF LITHOGRAPHY SYSTEM

摘要

PURPOSE: To improve the resolution of a system by inserting a filter for blocking the 0-th beam at a position where a Fraunhofer diffraction pattern of a mask appears to double the grating frequency. CONSTITUTION: A spatial filter 22 is inserted at a position in a projection system where a Fraunhofer diffraction pattern of a mask 18 appears and involves a center dark point which blocks the 0-th beam of the diffraction pattern from reaching the surface of a wafer 20. Owing to this blocking, an irradiation reaching the wafer surface does not form an image of a mask grating but interferes with the prim. beam passing through an opening of the film 22. This doubles the irradiation period to improve the resolution, compared with that of a standard projection system.