US4943734A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Inspection apparatus and method for detecting flaws on a diffractive surface
Assignee: QC Optics Inc
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Filing: 1989-06-30
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Granted: 1990-07-24
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Expires: 2009-06-30
Abstract
Abstract An optical inspection system and method for detecting flaws on a diffractive surface such as a reticle or wafer, includes illuminating a surface to be inspected to generate a first scattered energy angular distribution in response to a flaw on the surface and a second scattered energy angular distribution in response to an unflawed surface; the first and second energy distributions are sensed and the minimum energy detection energy level is established; determining whether the minimum detected energy level is in a first or second predetermined energy range and indicating that no flaw is present when the minimum detected energy level is in the first range and a flaw is present when the minimum detected energy level is in the second range.
Inventors
- 👤 Carl E. A. Johnson
- 👤 Jay L. Ormsby
- 👤 Eric T. Chase
- 👤 George S. Quackenbos
- 👤 Sergey V. Broude
- 👤 Abdu Bou dour
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:13
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/95; G01N21/956; G01N21/95607; G01N21/17; G01N21/47; G01N2021/4704; G01N2021/4711; G01N2021/4714; G01N2021/95676; G01N2201/00; G01N2201/10; G01N2201/108; G01N2201/1085
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
140 words
An optical inspection system for detecting flaws on a diffractive surface, comprising: means for illuminating a surface to be inspected to generate a first scattered energy angular distribution in response to a flaw on the surface, or a second scattered energy angular distribution in response to an unflawed surface; means for sensing said first and second energy distributions; means, responsive to the means for sensing, for establishing the minimum detected energy level within said angular distribution; means, for detecting whether said minimum detected energy level is in a first predetermined energy range or a second predetermined energy range; and means, responsive to said means for determining, for indicating that no flaw is present when said minimum energy detection level is in said first range and a flaw is present when said minimum detected energy level is in said second range.
Claim 2
Dependent Claim
140 words
An optical inspection system for detecting flaws on a diffractive surface, comprising: means for illuminating a surface to be inspected to generate a first scattered energy angular distribution in response to a flaw on the surface, or a second scattered energy angular distribution in response to an unflawed surface; means for sensing said first and second energy distributions; means, responsive to the means for sensing, for establishing the minimum detected energy level within said angular distribution; means, for detecting whether said minimum detected energy level is in a first predetermined energy range or a second predetermined energy range; and means, responsive to said means for determining, for indicating that no flaw is present when said minimum energy detection level is in said first range and a flaw is present when said minimum detected energy level is in said second range.
Claim 3
Dependent Claim
23 words
The system of claim 1 in which said first range includes the noise level and said second range is above the noise level.
Claim 4
Dependent Claim
20 words
The system of claim 1 in which said first range is generally zero and said second range is above zero.
Claim 5
Dependent Claim
15 words
The system of claim 1 in which said first range extends above the noise level.
Claim 6
Dependent Claim
20 words
The system of claim 1 in which said means for illuminating includes means for producing a narrow beam of radiation.
Claim 7
Dependent Claim
14 words
The system of claim 5 in which said means for producing includes a laser.
Claim 8
Dependent Claim
22 words
The system of claim 5 in which said means for illuminating includes means for scanning said narrow beam across said diffractive surface.
Claim 9
Dependent Claim
27 words
The system of claim 1 in which said means for sensing includes a plurality of photocells for monitoring a scan line illuminated by said means for illuminating.
Claim 10
Dependent Claim
40 words
The system of claim 8 in which said means for sensing includes an optical head including a set of segments, each segment including a plurality of elements, said segments and elements being aligned with the direction of said scan line.
Claim 11
Dependent Claim
20 words
The system of claim 9 in which the number of photocells corresponds to the number of elements in a segment.
Claim 12
Dependent Claim
17 words
The system of claim 10 in which each photocell is connected to one element in each segment.
Claim 13
Dependent Claim
27 words
The system of claim 11 in which the element in each segment to which a particular photocell is connected is in the same position in each segment.
Claim 14
Dependent Claim
25 words
The system of claim 8 in which said means for establishing the minimum detected energy level includes a minimum level detector responsive to said photocells.
Claim 15
Dependent Claim
39 words
The system of claim 1 in which said means for determining includes a reference level defining said first and second ranges and comparator means responsive to said means for establishing the minimum detected energy level and said reference level.
Claim 16
Dependent Claim
30 words
The system of claim 9 in which said optical head includes a number of sets of segments adjacent to one another and aligned with the direction of said scan line.
Claim 17
Dependent Claim
111 words
An optical inspection method for detecting flaws on a diffractive surface, comprising: illuminating a surface to be inspected to generate a first scattered energy angular distribution in response to a flaw on the surface and a second scattered energy angular distribution in response to an unflawed surface; sensing the first and second energy distributions; establishing the minimum detected energy level; determining whether the minimum detected energy level is in a first or second predetermined energy range; and indicating that no flaw is present when the minimum detection energy level is in the first range and that a flaw is present when the minimum detection energy level is in the second range.
Claim 18
Dependent Claim
111 words
An optical inspection method for detecting flaws on a diffractive surface, comprising: illuminating a surface to be inspected to generate a first scattered energy angular distribution in response to a flaw on the surface and a second scattered energy angular distribution in response to an unflawed surface; sensing the first and second energy distributions; establishing the minimum detected energy level; determining whether the minimum detected energy level is in a first or second predetermined energy range; and indicating that no flaw is present when the minimum detection energy level is in the first range and that a flaw is present when the minimum detection energy level is in the second range.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1993-07-23 | 1994-01-22 | 1994-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-23 | 1998-01-22 | 1998-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-23 | 2002-01-22 | 2002-07-24 | $7700.00 | Window Closed / Lapsed |