Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1997-04-09
1998-06-16
Le, Que
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
2505593, 2502081, 356401, G01N 2186
Patent
active
057675236
ABSTRACT:
A positioning, alignment, and image quality system comprising a detector having a photosensitive surface covered with an opaque layer having predetermined openings therein, a matched reticle having predetermined apertures therein is used to project the image of the apertures onto the openings. A plurality of different detectors are thereby formed on a single monolithic substrate for providing positioning, alignment, and image quality information. Different sub-detectors provide general positioning information, fine alignment or position information, and image quality information, such as optimum focus and astigmatism. In one embodiment, a pair of rectangular openings having a predetermined distance therebetween is used. An illumination pattern is projected between the rectangular openings filling a portion of the rectangular openings thereby providing a signal. The signals from the two openings are balanced or made equal to obtain positioning information or alignment of the reticle and the detector, and correspondingly a wafer stage attached to the detector. Different opening configurations in the opaque mask covering the photosensitive layer are used to provide different imaging information. The present invention permits alignment information to be obtained in a non-scanning system, as well as in a system using pulsed illumination sources. Additionally, a plurality of sub-detectors may easily be fabricated onto a monolithic detector providing different functions.
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Fattibene Arthur T.
Fattibene Paul A.
Le Que
SVG Lithography Systems, Inc.
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