Projection exposure apparatus and pattern forming method for use therewith

Abstract

A projection exposure apparatus has an effective source, a mask, a projection lens and an optical filter. The mask is illuminated with the light from the effective source having a substantially annular illumination distribution. The optical filter is disposed in the approximate position of the pupil plane of the projection lens. On the pupil plane, the transmittance of a first region is made lower than that of a second region, the first region being inside of the periphery of an annular region substantially conjugate with the effective source having the annular illumination distribution, the second region being outside of the periphery. Built in this manner, the apparatus forms fine patterns whose unit size is at least as small as the wavelength of the light used while maintaining high values of contrast and deep levels of focal length.

Dependencies are inferred from the claim text.