Optics: measuring and testing – By polarized light examination – With light attenuation
Patent
1983-12-19
1987-10-20
Evans, F. L.
Optics: measuring and testing
By polarized light examination
With light attenuation
250548, 250557, 356400, 356401, G01B 1100
Patent
active
047010533
ABSTRACT:
In a mark position-detecting apparatus, a rectangular reference mark is performed on a workpiece or photomask. The apparatus includes a movable table for supporting the photomask, a stationary light source for radiating light for forming a light spot on the photomask, a photodetector for detecting a change in light component transmitted through the mask, and a computer control section. The table moves forwardly and reversely in a Y-direction so that the photodetector scans two opposite edges of the reference mark in opposite directions in the Y-direction. The table is then moved forwardly and reversely in a X-direction so that the photodetector scans other two opposite mark edges. The signal detector thus produces edge position data representing the four mark edge scanned. The computer control section computes the coordinates of the mark center based on the edge position data.
REFERENCES:
patent: 3598978 (1971-08-01), Rempert
patent: 4200393 (1980-04-01), Suzuki et al.
patent: 4203064 (1980-05-01), Suzuki
patent: 4292576 (1981-09-01), Watts
patent: 4301470 (1981-11-01), Pagang
Carson et al., IBM Technical Disclosure Bulletin, vol. 21, No. 2, Jul. 1978.
An Automatic Reticle and Mask Defect Inspecting Apparatus, D. Awamura, "Denshi Zairyo", Jun. 1982.
"An Automatic Mask and Reticle Inspection System", Hal Yang, Proceeding of the Society of Photo-Optical Instrumentation Engineers, Mar. 31, 1982.
Evans F. L.
Tokyo Shibaura Denki Kabushiki Kaisha
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