Optics: measuring and testing – Refraction testing – Prism engaging specimen
Patent
1976-12-01
1978-10-31
Corbin, John K.
Optics: measuring and testing
Refraction testing
Prism engaging specimen
356168, G01B 1100
Patent
active
041231708
ABSTRACT:
An apparatus for detecting defects in patterns, particularly defects in chip patterns of photomasks used for manufacturing semi-conductor integrated circuits comprises means such as a flying spot scanner for producing a scanning light spot, an optical system for projecting said scanning light spot simultaneously on to identical portions of two patterns to be compared with each other, said patterns being placed on a carrier stage, first and second photoelectric converters, each converter receiving the light spot passing through or reflected from a respective pattern to produce an output electrical signal; and an electric circuit for receiving the output signals from said first and second photoelectric converters and subtracting one of them from the other to produce a difference signal which represents detected defects in the patterns. The electric circuit means further comprise a delay circuit for delaying before subtraction one of the signals from the photoelectric converters or delaying said difference signal by a predetermined time period so as to delete pseudo-defects in the patterns.
REFERENCES:
patent: 3379829 (1968-04-01), Gambrell et al.
patent: 3811011 (1974-05-01), Hardy et al.
patent: 3944369 (1976-03-01), Cuthbert et al.
Awamura Daikichi
Uchiyama Yasushi
Corbin John K.
Nippon Jido Seigyo Ltd.
Rosenberger R. A.
LandOfFree
Apparatus for detecting defects in patterns does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for detecting defects in patterns, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for detecting defects in patterns will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1832913