| 摘要 |
PURPOSE:To make it possible to align two substances in a highly precise manner even when an exposing operation is being conducted by a method wherein an interference fringe is formed by interfering two-frequency alignment lights, having the wavelength differentiated from an exposing light, with each other, and the above-mentioned interference fringe is projected on the substances. CONSTITUTION:After the alignment light 10 emitted from a laser light source 9 has been split into two components in a split optical system 1, the light 10 is brought into a circularly polarized light. The split two-component light 10 is interfered by a downward-reflecting mirror 17 and it is made to irradiate on a reticle 1. Then, the alignment light 10, which passed through a correction optical system 18 is made incident on an alignment light deflection element 20, guided into exposure light flux and made incident on a projection lens 4. The light 10 which is made incident on the projection lens 4 is image-formed on a wafer alignment diffraction grating 6, and a progressing type interference fringe is formed again. A beat signal is picked up from the laser light source 9, the beat signal is led to outside an exposure light 8 by an element 20 through the lens 4, and it is inputted to a phase indicator together with the intensity signal of the diffracted beam 21 detected by a light detector 25. As a result, the amount of positional deviation of a wafer 2 can be recognized accurately. |
