US5883710A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Scanning system for inspecting anomalies on surfaces
Assignee: Tencor Instruments Inc
•
Filing: 1995-07-10
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Granted: 1999-03-16
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Expires: 2015-07-10
Abstract
Abstract A high sensitivity and high throughput surface inspection system directs a focused beam of light at a grazing angle towards the surface to be inspected. Relative motion is caused between the beam and the surface so that the beam scans a scan path covering substantially the entire surface and light scattered along the path is collected for detecting anamolies. The scan path comprises a plurality of arrays of straight scan path segments. The focused beam of light illuminates an area of the surface between 5-15 microns in width and this system is capable of inspecting in excess of about 40 wafers per hour for 150 millimeter diameter wafers (6-inch wafers), in excess of about 20 wafers per hour for 200 millimeter diameter wafers (8-inch wafers) and in excess of about 10 wafers per hour for 300 millimeter diameter wafers (12-inch wafers).
Inventors
- 👤 Mehrdad Nikoonahad
- 👤 Stanley E. Stokowski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:21
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/95; G01N21/9501; G01N21/94; G01N21/956
Claims Analysis
Total Claims: 48
Claim 1
Independent Claim
89 words
A method for detecting anomalies on a surface; comprising the steps of: directing a focused beam of light at a grazing angle towards said surface; causing relative motion between the beam and the surface so that the beam scans a scan path covering substantially the entire surface, said path including a plurality of arrays of scan path segments, wherein each of at least some of such scan path segments has a span shorter than the dimensions of the surface; and collecting light scattered along said path for detecting anomalies.
Claim 2
Independent Claim
89 words
A method for detecting anomalies on a surface; comprising the steps of: directing a focused beam of light at a grazing angle towards said surface; causing relative motion between the beam and the surface so that the beam scans a scan path covering substantially the entire surface, said path including a plurality of arrays of scan path segments, wherein each of at least some of such scan path segments has a span shorter than the dimensions of the surface; and collecting light scattered along said path for detecting anomalies.
Claim 3
Dependent Claim
39 words
The method of claim 1, wherein said directing step directs said beam to illuminate an area of the surface defining a spot having a spot size whose minimum width is in the range of about 5 to 15 microns.
Claim 4
Dependent Claim
85 words
The method of claim 2, said surface being that of a semiconductor wafer, wherein the spot size and said directing and causing steps are such that the beam substantially inspects the entire surface of the wafer at a throughput in excess of about 40 wafers per hour for 150 mm diameter wafers, at a throughput in excess of about 20 wafers per hour for 200 mm diameter wafers, and at a throughput in excess of about 10 wafers per hour for 300 mm diameter wafers.
Claim 5
Dependent Claim
62 words
The method of claim 2, wherein the scan path segments comprise a plurality of straight scan path segments, wherein said directing and causing steps are such that the beam substantially inspects said surface along said scan path segments at such speed that the surface is inspected along said scan path segments at a speed not less than about 2.5 cm 2 /s.
Claim 6
Dependent Claim
56 words
The method of claim 4, wherein the spot size and said directing and causing steps are such that the beam substantially inspects said surface along said scan path segments at such speed that the surface is inspected along said scan path segments at a speed in a range of about 2.5 to 3.8 cm 2 /s.
Claim 7
Dependent Claim
43 words
The method of claim 2, wherein the spot size and said directing and causing steps are such that the beam substantially inspects said surface at such speed that the surface is inspected at a speed not less than about 1.5 cm 2 /s.
Claim 8
Dependent Claim
46 words
The method of claim 6, wherein the spot size and said directing and causing steps are such that the beam substantially inspects said surface at such speed that the surface is inspected at a speed in the range of about 1.5 to 5 cm 2 /s.
Claim 9
Dependent Claim
47 words
The method of claim 2, said surface having dimensions of not less than 200 mm in any direction along the surface, wherein the spot size and said directing and causing steps are such that the beam scans substantially the entire surface in about 50 to 90 seconds.
Claim 10
Dependent Claim
58 words
The method of claim 2, said method employing an acousto-optic deflector for deflecting the light beam in order to scan said surface, said method further comprising expanding the optical beam before it is deflected by the deflector, so that the beam before deflection has at least one cross-sectional dimension in the range of about 4 to 12 mm.
Claim 11
Dependent Claim
36 words
The method of claim 1, wherein the scan path segments comprise a plurality of arrays of substantially parallel and straight scan path segments, wherein the segments are substantially in a range of about 2-10 mm long.
Claim 12
Dependent Claim
73 words
The method of claim 1, wherein said directing step directs said beam to illuminate an area of the surface defining a spot, said beam having an intensity distribution in reference to two axes across the spot, said method further comprising taking a number of samples of the light scattered from any anomaly, if any, in the spot along each of the two axes, said number being in the range of 2 to 10.
Claim 13
Dependent Claim
33 words
The method of claim 1, wherein said directing step is such that the angle between the beam and normal direction to the surface is in the range of about 10 to 85 degrees.
Claim 14
Dependent Claim
33 words
The method of claim 12, wherein said directing step is such that the angle between the beam and normal direction to the surface is in the range of about 50 to 80 degrees.
Claim 15
Dependent Claim
49 words
The method of claim 1, said method employing an acousto-optic deflector for deflecting the light beam in order to scan said surface, said directing and causing steps including driving the deflector with a linear FM chirp signal with a center frequency in the range of 50 to 300 MHz.
Claim 16
Dependent Claim
48 words
The method of claim 1, said method employing an acousto-optic deflector for deflecting the light beam in order to scan said surface, said directing and causing steps including driving the deflector with a linear FM chirp signal with a bandwidth in the range of 50 to 250 MHz.
Claim 17
Dependent Claim
31 words
The method of claim 15, further comprising supplying a linear FM chirp signal to drive the acousto-optic deflector so that the chirp duration is in the range 20 to 200 microseconds.
Claim 18
Dependent Claim
33 words
The method of claim 15, further comprising supplying a linear FM chirp signal to drive the acousto-optic deflector so that the chirp duration is in the range of about 80 to 120 microseconds.
Claim 19
Dependent Claim
54 words
The method of claim 1, said method employing an acousto-optic deflector for deflecting the light beam in order to scan said surface, said method further comprising providing a scan lens substantially at one focal length away from the deflector and between the deflector and the surface so that the beam scans the surface telecentrically.
Claim 20
Dependent Claim
54 words
The method of claim 1, said method employing a polygon scanner for deflecting the light beam in order to scan said surface, said method further comprising providing a scan lens substantially at one focal length away from the deflector and between the deflector and the surface so that the beam scans the surface telecentrically.
Claim 21
Dependent Claim
20 words
The method of claim 1, said collecting step collecting light scattered along said scan path in the forward direction azimuthally.
Claim 22
Dependent Claim
55 words
The method of claim 20, said collecting step collecting light scattered along said scan path using four independent collection channels, two of said collection channels located in the forward direction to collect light in the forward direction substantially at ±45° azimuthally and two of the channels are located to collect light substantially at ±90° azimuthally.
Claim 23
Dependent Claim
40 words
The method of claim 21, each of said collection channels collects light in the range of 3 to 30° in the elevation direction, said channels collecting light in the respective ranges of azimuthal angles of -(75-105)°, (75-105)°, -(30-60)° and (30-60)°.
Claim 24
Dependent Claim
35 words
The method of claim 1, said method further comprising selecting a desired polarization state of a light beam that is directed in the directing step from S state, P state, or a circular polarization state.
Claim 25
Independent Claim
92 words
A system for detecting anomalies on a surface; comprising: means for directing a focused beam of light at a grazing angle towards said surface; means for causing relative motion between the beam and the surface so that the beam scans a scan path covering substantially the entire surface, said path including a plurality of arrays of scan path segments, wherein each of at least some of such scan path segments has a span shorter than the dimensions of the surface; and means for collecting light scattered along said path for detecting anomalies.
Claim 26
Independent Claim
92 words
A system for detecting anomalies on a surface; comprising: means for directing a focused beam of light at a grazing angle towards said surface; means for causing relative motion between the beam and the surface so that the beam scans a scan path covering substantially the entire surface, said path including a plurality of arrays of scan path segments, wherein each of at least some of such scan path segments has a span shorter than the dimensions of the surface; and means for collecting light scattered along said path for detecting anomalies.
Claim 27
Dependent Claim
39 words
The system of claim 24, wherein said directing means directs said beam to illuminate an area of the surface defining a spot having a spot size whose minimum width is in the range of about 5 to 15 microns.
Claim 28
Dependent Claim
85 words
The system of claim 25, said surface being that of a semiconductor wafer, wherein the spot size and said directing and causing means are such that the beam substantially inspects the entire surface of the wafer at a throughput in excess of about 40 wafers per hour for 150 mm diameter wafers, at a throughput in excess of about 20 wafers per hour for 200 mm diameter wafers, and at a throughput in excess of about 10 wafers per hour for 300 mm diameter wafers.
Claim 29
Dependent Claim
66 words
The system of claim 25, wherein the scan path segments comprise a plurality of straight scan path segments, wherein the spot size and said directing and causing means are such that the beam substantially inspects said surface along said scan path segments at such speed that the surface is inspected along said scan path segments at a speed not less than about 2.5 cm 2 /s.
Claim 30
Dependent Claim
56 words
The system of claim 27, wherein the spot size and said directing and causing means are such that the beam substantially inspects said surface along said scan path segments at such speed that the surface is inspected along said scan path segments at a speed in a range of about 2.5 to 3.8 cm 2 /s.
Claim 31
Dependent Claim
43 words
The system of claim 25, wherein the spot size and said directing and causing means are such that the beam substantially inspects said surface at such speed that the surface is inspected at a speed not less than about 1.5 cm 2 /s.
Claim 32
Dependent Claim
46 words
The system of claim 29, wherein the spot size and said directing and causing means are such that the beam substantially inspects said surface at such speed that the surface is inspected at a speed in the range of about 1.5 to 5 cm 2 /s.
Claim 33
Dependent Claim
47 words
The system of claim 25, said surface having dimensions of not less than 200 mm in any direction along the surface, wherein the spot size and said directing and causing means are such that the beam scans substantially the entire surface in about 50 to 90 seconds.
Claim 34
Dependent Claim
58 words
The system of claim 25, said system employing an acousto-optic deflector for deflecting the light beam in order to scan said surface, said system further comprising expanding the optical beam before it is deflected by the deflector, so that the beam before deflection has at least one cross-sectional dimension in the range of about 4 to 12 mm.
Claim 35
Dependent Claim
36 words
The system of claim 24, wherein the scan path segments comprise a plurality of arrays of substantially parallel and straight scan path segments, wherein the segments are substantially in a range of about 2-10 mm long.
Claim 36
Dependent Claim
73 words
The system of claim 24, wherein said directing means directs said beam to illuminate an area of the surface defining a spot, said beam having an intensity distribution in reference to two axes across the spot, said system further comprising taking a number of samples of the light scattered from any anomaly, if any, in the spot along each of the two axes, said number being in the range of 2 to 10.
Claim 37
Dependent Claim
32 words
The system of claim 24, wherein said directing means is such that the angle between the beam and normal direction to the surface is in the range of about 10° to 85°.
Claim 38
Dependent Claim
32 words
The system of claim 35, wherein said directing means is such that the angle between the beam and normal direction to the surface is in the range of about 50° to 80°.
Claim 39
Dependent Claim
49 words
The system of claim 24, said system employing an acousto-optic deflector for deflecting the light beam in order to scan said surface, said directing and causing means including driving the deflector with a linear FM chirp signal with a center frequency in the range of 50 to 300 MHz.
Claim 40
Dependent Claim
48 words
The system of claim 24, said system employing an acousto-optic deflector for deflecting the light beam in order to scan said surface, said directing and causing means including driving the deflector with a linear FM chirp signal with a bandwidth in the range of 50 to 250 MHz.
Claim 41
Dependent Claim
33 words
The system of claim 38, further comprising means for supplying a linear FM chirp signal to drive the acousto-optic deflector so that the chirp duration is in the range 20 to 200 microseconds.
Claim 42
Dependent Claim
35 words
The system of claim 38, further comprising means for supplying a linear FM chirp signal to drive the acousto-optic deflector so that the chirp duration is in the range of about 80 to 120 microseconds.
Claim 43
Dependent Claim
53 words
The system of claim 24, said system employing an acousto-optic deflector for deflecting the light beam in order to scan said surface, said system further comprising a scan lens substantially at one focal length away from the deflector and between the deflector and the surface so that the beam scans the surface telecentrically.
Claim 44
Dependent Claim
51 words
The system of claim 24, said system further comprising: a polygon scanner for deflecting the light beam in order to scan said surface; and a scan lens substantially at one focal length away from the deflector and between the deflector and the surface so that the beam scans the surface telecentrically.
Claim 45
Dependent Claim
20 words
The system of claim 24, said collecting means collecting light scattered along said scan path in the forward direction azimuthally.
Claim 46
Dependent Claim
55 words
The system of claim 43, said collecting means comprising four independent collection channels collecting light scattered along said scan path, two of said collection channels located in the forward direction to collect light in the forward direction substantially at ±45° azimuthally and two of the channels are located to collect light substantially at ±90° azimuthally.
Claim 47
Dependent Claim
40 words
The system of claim 44, each of said collection channels collects light in the range of 3° to 30° in the elevation direction, said channels collecting light in the respective ranges of azimuthal angles of -(75-105)°, (75-105)°, -(30-60)° and (30-60)°.
Claim 48
Dependent Claim
35 words
The system of claim 24, said system further comprising selecting a desired polarization state of a light beam that is directed in the directing means from S state, P state, or a circular polarization state.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-03-15 | 2002-09-14 | 2003-03-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-03-15 | 2006-09-14 | 2007-03-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-03-15 | 2010-09-14 | 2011-03-16 | $7700.00 | Window Closed / Lapsed |