Patent ID: 9046791
Filing Date: 2015-06-02
Classification: G01M,G02B,G03F

Abstract:
1. An apparatus for detecting wave front aberration of a projection objectNe lens in a photolithography machine, comprising: a light source system configured to generate an illuminating beam; a spatial filter configured to receive the illuminating beam and to generate an ideal spherical wave; a splitter plate arranged downstream to the spatial filter at a predetermined angle with respect to an optical axis of the spherical wave and having a transflective film being applied on a surface thereof; a projection objective lens configured to receive a beam from the splitter plate and generate an output beam; a spherical mirror configured to reflect the output beam from the projection objective lens to the projection objective lens, light passing through the projection objective lens being reflected by the splitter plate; and an interferometer configured to receive light reflected by the splitter plate and measure the wave front aberration of the projection objective lens, wherein the interferometer comprises: a beam divider device configured to diffract the light reflected by the splitter plate, the beam divider device being constituted by two one-dimensional binary amplitude gratings or two one-dimensional binary phase gratings having orthogonal reticle directions; an image-plane spatial filter arranged downstream to the beam divider and having windows allowing predetermined orders of diffraction light; a data collection unit configured to collect interference patterns of light passing through the windows; a computer configured to process the collected interference pattern data to obtain the wave front aberration, and a stage configured to carry the two one-dimensional binary amplitude gratings or two one-dimensional binary phase gratings and to move in two dimensional directions precisely.