| 摘要 |
In an X-Y addressable workpiece positioner the workpiece to be positioned, such as a semiconductive wafer to be aligned with a mask image, is coupled to move with a work stage moveable in X and Y direction and having a two-dimensional array of positioning indicia affixed thereto for movement therewith. An enlarged image of a portion of the positioning array is projected onto a relatively stationary sensor stage to derive an output determinative of the X and Y coordinates of the positioning array relative to the position of the sensor. The sensed X and Y coordinates of the positioning array are compared with the X and Y coordinates of a reference positioning address to derive an error output. The work stage is moved in response to the error output for causing the workpiece to be positioned to the reference address. In a preferred embodiment of a mask aligner, the approximately stationary sensing stage is moved relative to the enlarged image of the positioning array for interpolating the X and Y coordinates of the sensed address. A viewing system is arranged for permitting the operator to superimpose the image of a pattern on the reference addressed position of the semiconductive wafer with a mask image. The sensing stage is moved by the operator to obtain precise registration of the images, thereby zeroing the reference position address to the interpolated value. The machine then sequentially steps the interpolated (zeroed) reference position address by predetermined increments, related to the size mask pattern to be projected onto the wafer, to cause the wafer to be sequentially exposed to the mask pattern in different regions thereof.
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