Method of measuring relative positioning accuracy of a pattern to be formed on a semiconductor wafer

摘要

To determine the position of a mask pattern formed on a surface of a semiconductor wafer (1) relative to the position of a reference pattern previously formed on the surface, a photosensitive film (8) is applied to the surface, and areas of the film are selectively irradiated with light via a photo mask to form a latent image of the mask pattern of exposed and unexposed areas of film. The reference and mask patterns include diffracting portion (4) and (5) respectively. Relative movement is effected between the wafer and a laser beam (6) so that the diffracting portions (4) and (5) of the reference and mask patterns are successively irradiated by the beam. Laser light is diffracted by the reference portion (4) and also by the mask portion (5) due to the difference between the indices of refraction of the exposed and unexposed parts of the latent image prior to development thereof. The spacing between the resulting diffraction patterns is measured to determine the spacing (x) between the reference and mask patterns.