Method and apparatus for increasing the resolution power of projection lithography exposure system

摘要

A method and apparatus for transferring a fine pattern (12) on a mask (11) onto a substrate (17) by a projection exposure apparatus including an illumination optical system (1-10) for irradiating an illuminating light on the mask (11), and a projection optical system (13) for projecting an image of the fine pattern (12) on the illuminated mask onto the substrate (17). The illuminating light is irradiated at least in the form of a pair of light beams opposedly inclined with respect to the mask through a pair of transparent windows (6a, 6b) of a spatial filter (6) whereby either one of the .+-.first-order diffracted beams and the 0- order diffracted beam produced from the fine pattern (12) of the mask (11) illuminated by each said light beam are respectively passed apart by the equal distance from the optical axis of the projection optical system at or near to the Fourier transform plane within the projection optical system with respect to the fine pattern (12) of the mask (11), thereby forming on the substrate (17) a high-resolution projected image of a strong light-and-dark contrast with a high degree of focus depth. (FIG. 1)