Filter manufacturing apparatus

Abstract

A projection exposure apparatus is constituted by a first focusing optical system for focusing light from a mercury-vapor lamp as a light source, a uniforming optical system for uniforming the focused light, a second focusing optical system for focusing the uniformed light and radiating the light onto a reticle mask, and a projection optical system for projecting the light, transmitted through the reticle, onto a wafer. The apparatus is designed to project/expose a predetermined mask pattern, formed on the mask, onto the wafer through the projection optical system. A special stop (i.e., a four-eye filter) is arranged as a secondary source for uniformly illuminating the mask. The special stop serves to set an intensity distribution within the exit plane of the secondary source such that intensities in four regions quadruple-symmetrical about the optical axis of the secondary source and decentered therefrom are higher than intensities in other regions. A translucent pattern is formed as the mask on a light-transmitting substrate. The phase difference between light passing through the translucent film and light passing through the light-transmitting substrate is represented by 180.times.(2n+1).+-.30 (degree) (where n is an integer). In addition, the apparatus includes a halftone mask which allows an amplitude transmittance T of the translucent film and an amplitude transmittance T0 of the light-transmitting substrate to satisfy 0.01.times.T0.ltoreq.T.ltoreq.0.30.times.T0. Furthermore, a projection exposure apparatus is provided, in which a light source and a secondary source is coupled to each other through fibers, and an optical modulator is inserted therebetween so that the spatial distribution of light amounts can be electrically and optically controlled.