Process for positioning a mask relative to a workpiece and device

Abstract

An exposure device in which alignment is performed using light with wavelengths which are different from those of the exposure light, to position the mask to the workpiece with high accuracy by the magnification factor in emission of exposure light being brought into agreement with the magnification factor for emission of nonexposure light. Changes in the focal length and movements of the main planes of the projection lens due to the different wavelengths are taken into consideration in adjusting the distance between the mask and the projection lens and the distance between the projection lens and the workpiece. In this way, the length of the optical path of the optical system is adjusted such that the magnification factor in the emission of nonexposure light matches the magnification factor in emission of exposure light. Then, the nonexposure light is emitted onto a mask, and the workpiece drive carrier or the mask drive carrier is moved such that the alignment identifier of the workpiece with the alignment identifier of the mask come to lie one on top of the other. Furthermore, instead of adjusting the distance between the mask and the projection lens and the distance between the projection lens and the workpiece, an optical part such as a parallel flat plate or the like is inserted into the optical path for adjusting its length.