Patent EP0819933A2 successfully refreshed from Google Patents.
EP0819933A2
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EP
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Optical inspection method and apparatus
Assignee: Orbot Instruments Ltd
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Filing: 1997-07-01
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Granted: —
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Expires: 2017-07-01
Abstract
Abstract Apparatus for optically inspecting an object (eg photomask PM) having upper and lower faces for indicating the condition of the object, includes a lighting system (4, 12) periodically reflecting a beam of light from one face of the object (PM) to produce a series of short-duration time-spaced reflected beams, and periodically transmitting a beam of light through both faces of the object (PM) to produce a series of short-duration time-spaced transmitted beams time-interlaced with the reflected beams, a sensor (20) sensing the short-duration time-spaced reflected beams and transmitted beams, and generating electrical outputs corresponding thereto, and processor (32) receiving the electrical outputs and processing them to provide an indication of the condition of the object. A method of optically inspecting an object having upper and lower faces for indicating the condition of the object is also described.
Inventors
- 👤 Emanuel Elyasaf
- 👤 Yair Eran
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 03:04
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/84; G01N21/88
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
99 words
A method of optically inspecting an object having upper and lower faces for indicating the condition of the object, comprising: periodically reflecting a beam of light from one face of the object to produce a series of short-duration time-spaced reflected beams; periodically transmitting a beam of light through the object including both faces thereof to produce a series of short-duration time-spaced transmitted beams time- interlaced with said reflected beams; sensing said short-duration time-spaced reflected beams and transmitted beams, and generating electrical outputs corresponding thereto; and processing said electrical outputs to provide an indication of the condition of said object.
Claim 2
Dependent Claim
21 words
The method according to Claim 1, wherein said reflected beam and transmitted beams are sensed by an area- type image sensor.
Claim 3
Dependent Claim
25 words
The method according to Claim 2, wherein said reflected beams and transmitted beams are produced by separate light sources on opposite sides of the object.
Claim 4
Dependent Claim
42 words
The method according to Claim 2, wherein said reflected beams and transmitted beams are produced by a common light source on one side of the object, and optical steering elements alternatingly steering the light beam to the opposite sides of the object.
Claim 5
Independent Claim
24 words
The method according to either of Claims 3 or 4, wherein said reflected beams and transmitted beams are sensed by a common image sensor.
Claim 6
Dependent Claim
59 words
The method according to Claim 2, wherein said reflected beams and transmitted beams are produced by a single light source on one side of the object, said reflected beams are sensed by a first sensor on said one side of the object, and said transmitted beams are sensed by a second sensor on the opposite side of the object.
Claim 7
Dependent Claim
32 words
The method according to Claim 1, wherein each of said reflected beams and transmitted beams is produced by a high intensity light source periodically energized for periods of less than 1 millisecond.
Claim 8
Dependent Claim
40 words
The method according to Claim 7, wherein each of said reflected beams and transmitted beams is produced by a high intensity light source periodically energized for periods of less than 100 microseconds at a frequency of more than 1 MHz.
Claim 9
Independent Claim
18 words
The method according to either of Claims 7 or 8, wherein said high-intensity light source is a laser.
Claim 10
Dependent Claim
44 words
The method according to Claim 1, wherein the object being optically inspected is a photomask having clear areas and opaque areas, and the condition to be indicated is the presence or absence of defects in said clear areas and opaque areas of the photomask.
Claim 11
Dependent Claim
107 words
Apparatus for optically inspecting an object having upper and lower faces for indicating the condition of the object, comprising: a lighting system periodically reflecting a beam of light from one face of the object to produce a series of short-duration time-spaced reflected beams, and periodically transmitting a beam of light through both faces of the object to produce a series of short-duration time-spaced transmitted beams time-interlaced with said reflected beams; a sensor sensing said short-duration time-spaced reflected beams and transmitted beams, and generating electrical outputs corresponding thereto; and a processor receiving said electrical outputs and processing them to provide an indication of the condition of said object.
Claim 12
Dependent Claim
14 words
The apparatus according to Claim 11, wherein said sensor comprises an area-type image sensor.
Claim 13
Dependent Claim
20 words
The apparatus according to Claim 12, wherein said area-type image sensor includes a rectangular matrix of charge coupled devices (CCDs).
Claim 14
Independent Claim
25 words
The apparatus according to either of Claims 12 or 13, wherein said lighting system comprises first and second light sources on opposite sides ofthe object.
Claim 15
Independent Claim
87 words
The apparatus according to either of Claims 12 or 13, wherein said lighting system comprises: a common light source on one side of the object producing short-duration time-spaced light beams; a first optical system on said one side of the object; a second optical system on the opposite side of the object; and a light-beam steering device on said one side of the object periodically controlled to steer the light from said common light source alternatingly to said first optical system and to said second optical system.
Claim 16
Dependent Claim
15 words
The apparatus according to Claim 15, wherein said light-beam steering device includes a flip-flop mirror.
Claim 17
Dependent Claim
22 words
The apparatus according to Claim 11, wherein said sensor is an area-type sensor sensing both said reflected beams and said transmitted beams.
Claim 18
Independent Claim
61 words
The apparatus according to either of Claims 12 or 13, wherein: said lighting system comprises a single periodically-energized light source on one side of the object; and said sensor comprises a first sensor on said one side of the object for sensing the reflected beams, and a second sensor on the opposite side of the object for sensing the transmitted beams.
Claim 19
Dependent Claim
23 words
The apparatus according to Claim 11, wherein said lighting system is periodically energized to produce high-intensity beams of less than 1 millisecond duration.
Claim 20
Dependent Claim
31 words
The apparatus according to Claim 19, wherein said lighting system is periodically energized to produce high-intensity beams of less than 100 microseconds duration at a frequency of more than 1 MHz.
Claim 21
Dependent Claim
15 words
The apparatus according to Claim 11, wherein said lighting system includes a periodically- energized laser.
References Cited (Backward Citations)
No citation records indexed.
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