Electricity: motive power systems – Positional servo systems – With particular 'error-detecting' means
Patent
1981-07-27
1984-04-10
Combs, E. Michael
Electricity: motive power systems
Positional servo systems
With particular 'error-detecting' means
29407, 250201, G05B 106, G01J 120
Patent
active
044423888
ABSTRACT:
In an X-Y addressable workpiece positioner, the workpiece to be positioned, such as a semiconductive wafer to be sequentially exposed at different regions thereof in accordance with a pattern of a mask, is disposed for movement with a work stage along coordinate X and Y axes. The work stage has a two-dimensional array of X and Y coordinate addressing indicia enclosed within a border and affixed to the work stage for movement therewith. A portion of an enlarged image of the array of addressing indicia is projected onto a sensor stage to derive an output indicative of the X and Y coordinates of the array of addressing indicia relative to the position of the sensor stage. The X and Y coordinates of the array of addressing indicia are sensed through addressing indicia recognition windows of the sensor stage and are differentially compared to remove unwanted background effects. Concomitantly, the border is sensed through border sensing windows of the sensor stage to provide a frame of reference for the sensed X and Y coordinates of the array of addressing indicia. The sensed X and Y coordinates of the array of addressing indicia are compared with the X and Y coordinates of a selected addressed position of the work stage to derive an error output. In response to this error output the work stage is moved to the selected addressed position so as to position a region of the workpiece for exposure in accordance with the pattern of the mask. The work stage is sequentially moved to succeeding addressed positions in the same maner to position each of the remaining regions of the workpiece for exposure in accordance with the pattern of the mask.
REFERENCES:
patent: 3581375 (1971-06-01), Rottmann
patent: 3634689 (1972-01-01), Ejiri et al.
patent: 3712740 (1973-01-01), Hennings
patent: 3821545 (1974-06-01), Nakagawa et al.
patent: 3902615 (1975-09-01), Levy et al.
patent: 3943359 (1976-03-01), Matsumoto et al.
patent: 4057347 (1977-11-01), Moriyama et al.
Aine Harry E.
Combs E. Michael
Griffin Roland I.
Optimetrix Corporation
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