Aligning exposure method

Abstract

Disclosed in an aligning and exposing method suitable for use in the production of LSIs. Coherent ray beams are applied from two directions to form interference fringe through interference of the coherent rays. A diffraction grid is disposed in the optic paths of the ray beams substantially in parallel with the interference fringe. The ray beams reflected and transmitted by the grid are converged by a lens system and the intensities of the ray beams are measured to detect the relative position between the interference fringe formed by two coherent ray beams and the diffraction grid, thereby to permit a highly accurate alignment of fine semiconductor element. The pitch of the grid on the substrate is selected to be n (n being an integer) times as large as the pitch of the interference fringe, so that the grid for alignment purpose is formed simultaneously with the formation of the LSI pattern by photolithographic technic. With this method, it is possible to attain a high degree of accuracy of alignment, and to conduct the subsequent exposure using the same ray beam source as that used for the alignment.