摘要：

A step-and-repeat alignment and exposure system is provided with a main stage controlled for movement along orthogonal X and Y axes to position either a reference mark or a semiconductive wafer directly beneath a projection lens of the reduction type. The reference mark is formed on a reference mark plate mounted on a substage which is in turn mounted on the main stage and provided with adjustment screws for manually positioning the reference mark plate in a plane parallel to an image plane of the projection lens and for manually positioning the reference mark in alignment with one of the axes of motion of the main stage. Another stage is disposed above the projection lens and controlled for movement along the X and Y axes and about an orthogonal Z axis to position a reticle, held by a vacuum holder and selectively illuminated by a light source unit, with respect to the reference mark. Images of the illuminated portions of the reticle are projected onto the reference mark or the semiconductive wafer by the projection lens. A beam splitter is disposed between the projection lens and the reticle to provide a port for viewing aerial images of the portions of the reference mark or the semiconductive wafer illuminated by the projected images of the illuminated portions of the reticle.

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