US5083035A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Position location in surface scanning using interval timing between scan marks on test wafers
Assignee: Tencor Instruments Inc
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Filing: 1990-07-17
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Granted: 1992-01-21
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Expires: 2010-07-17
Abstract
Abstract A particle imager and method for imaging particles on surfaces of substrates. A surface is raster scanned by a collimated light beam and particles on the surface are detected by the scattered light caused by the particles. During a scan path the intensity of the scattered light is measured forming intensity traces and location addresses for the detected particles. Data from each scan path is stored in memory. The imager is pre-calibrated with a test wafer having light scattering marker points spaced at known positions thereon. Scanning the test wafer, a clock measures time elapsed from a start position to each marker point. The corresponding elapsed times and known address locations are stored in memory for reference during data collection.
Inventors
- 👤 Jiri Pecen
- 👤 Kenneth P. Gross
- 👤 Brian Leslie
- 👤 George Kren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 14:10
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70483; G01; G01N; G01N21/00; G01N21/84; G01N21/88; G01N21/94; G02; G02B; G02B17/00; G02B17/02; G02B17/06; G01N21/17; G01N21/47; G01N2021/4704; G01N2021/4711; G01N2021/4719; G01N21/93; G01N21/95; G01N21/956; G01N21/95607
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
180 words
A method of determining the position of a scanning beam as it traverses a surface of a wafer in a path comprising: establishing a starting first location for a scan by positioning a scan start marker near an edge of a scan path, for a test wafer with optical marker points spaced at known locations across the wafer surface in said path, scanning the test wafer with scanning optics in a first scan and timing the beam from the scan start marker to each successive marker point, each of the marker points having a unique address, for each marker point address, storing in a memory the elapsed time from the start marker to the marker point address so that each address has a corresponding elapsed time associated therewith, for an unknown wafer, scanning the unknown wafer in a second scan using the same path and the sam scanning optics as said first scan and measuring the elapsed time from the scan start marker, and associating elapsed measured times corresponding to said stored addresses with beam position on the unknown wafer.
Claim 2
Independent Claim
180 words
A method of determining the position of a scanning beam as it traverses a surface of a wafer in a path comprising: establishing a starting first location for a scan by positioning a scan start marker near an edge of a scan path, for a test wafer with optical marker points spaced at known locations across the wafer surface in said path, scanning the test wafer with scanning optics in a first scan and timing the beam from the scan start marker to each successive marker point, each of the marker points having a unique address, for each marker point address, storing in a memory the elapsed time from the start marker to the marker point address so that each address has a corresponding elapsed time associated therewith, for an unknown wafer, scanning the unknown wafer in a second scan using the same path and the sam scanning optics as said first scan and measuring the elapsed time from the scan start marker, and associating elapsed measured times corresponding to said stored addresses with beam position on the unknown wafer.
Claim 3
Dependent Claim
18 words
The method of claim 1 wherein establishing said starting location is by scattering light from a surface irregularity.
Claim 4
Dependent Claim
25 words
The method of claim 1 wherein establishing said starting location is by detecting the shadow of the marker on a detector placed behind the marker.
Claim 5
Dependent Claim
17 words
The method of claim 1 wherein said optical marker points on said test wafer are equidistantly spaced.
Claim 6
Dependent Claim
53 words
The method of claim 4 further defined by computing, for an ideal scanner, theoretical elapsed times at said equidistant marker points and comparing the theoretical elapsed times with actual measured elapsed times at marker points, the difference at each equidistant marker point indicating a difference between an ideal scanner and the actual scanner.
Claim 7
Dependent Claim
22 words
The method of claim 1 wherein locations of said optical markers are stored for equally spaced time intervals of a beam scan.
Claim 8
Dependent Claim
46 words
The method of claim 1 further comprising establishing a second starting location on an opposite side of a scan from the first starting location, the second starting location established by positioning a scan start marker near an edge of a scan path opposite the first edge.
Claim 9
Dependent Claim
40 words
The method of claim 7 wherein scatter data is collected from said unknown wafer with the laser beam moving alternately in both directions from first starting location to second starting location and from second starting location to first starting location.
Claim 10
Dependent Claim
31 words
The method of claim 1 further defined by using one or more markers to produce a reference scatter signal whose amplitude is used to control the gain of the detection system.
Claim 11
Independent Claim
174 words
A method of determining the position of a scanning beam as it traverses a surface of a wafer in a path comprising, marking the starting edge of a scan path with a first light scattering feature, for a test wafer with equidistant optical scattering features spaced at known positions across the wafer surface in said path, scanning the test wafer with scanning optics in a first scan and timing the beam from the scan start marker to each successive scattering feature, each of the scattering features having a unique address, for each marker point address, storing in a memory the elapsed time from the start marker to the marker point address so that each address had a corresponding elapsed time associated therewith, for an unknown wafer, scanning the unknown wafer in a second scan using the same path and the same scanning optics as said first scan and measuring the elapsed time from the scan start marker, and associating elapsed measured times corresponding to said stored addresses with beam position on the unknown wafer.
Claim 12
Independent Claim
174 words
A method of determining the position of a scanning beam as it traverses a surface of a wafer in a path comprising, marking the starting edge of a scan path with a first light scattering feature, for a test wafer with equidistant optical scattering features spaced at known positions across the wafer surface in said path, scanning the test wafer with scanning optics in a first scan and timing the beam from the scan start marker to each successive scattering feature, each of the scattering features having a unique address, for each marker point address, storing in a memory the elapsed time from the start marker to the marker point address so that each address had a corresponding elapsed time associated therewith, for an unknown wafer, scanning the unknown wafer in a second scan using the same path and the same scanning optics as said first scan and measuring the elapsed time from the scan start marker, and associating elapsed measured times corresponding to said stored addresses with beam position on the unknown wafer.
References Cited (Backward Citations)
US4329011A
Cited
US4404596A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-01-20 | 1995-07-22 | 1996-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-01-20 | 1999-07-22 | 2000-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-01-20 | 2003-07-22 | 2004-01-21 | $7700.00 | Window Closed / Lapsed |