Importance

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Abstract

Disclosed is an exposure apparatus for printing a pattern of a reticle on different shot areas of the wafer in a step-and-repeat manner. In the disclosed apparatus, an image of an alignment mark of the reticle is printed, by use of a projection lens system, on each of some shot areas of the wafer which are selected as the subject of detection. By this, a latent image of the reticle mark is formed on each of the selected shot areas. The latent image of the reticle mark is detected by a microscope which may be a phase contrast microscope and, from the results of detection concerning all the latent images of the reticle mark, a reference (correction) grid representing the coordinate positions of all the shot areas of the wafer is prepared and stored. In accordance with the stored reference grid, the stepwise movement of the wafer is controlled at the time of the step-and-repeat exposures of the wafer. This assures improved throughput of the apparatus. Further, use of the phase contrast microscope for the detection of the latent image of the reticle mark ensures further improvement in the alignment accuracy.

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First Claim