US4958129A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Prealigner probe
Assignee: ADE Corp
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Filing: 1989-03-07
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Granted: 1990-09-18
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Expires: 2009-03-07
Abstract
Abstract An edge detection system for measuring lateral position in the presence of height variations such as found in gauging the edge position of a wafer uses first and second capacitive probes formed of passive elements with the active components kept outside the probe and at a distance that permits a smaller, stabler and more economical probe to be located at the location of the wafer. The probes are instrumented in an electronic circuit having plural operational amplifiers that drive the probes to compensate the edge detection for wafer height effects.
Inventors
- 👤 Noel S. Poduje
- 👤 Roy E. Mallory
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 02:46
CPC Classifications
G; G01; G01B; G01B7/00; G01B7/02; G01B7/023
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
158 words
A system for capacitive edge detection of a supported member comprising: a member where the position of an edge of said member is to be detected; a first probe positioned proximate to said member near the edge thereof and having a parameter varying as a function both of a distance from said probe to said member and displacement of a portion of said probe beyond the edge of said member; a second probe positioned near said first probe and closer to an interior location of said member than said first probe, said second probe having a parameter varying with distance of said second probe from said member; a first operational amplifier having the capacitance sensed by the electrode of the first probe in a feedback loop thereof; a second operational amplifier having the capacitance sensed by the electrode of the second probe in an input circuit thereof and; a source of A.C. excitation driving said first operational amplifier.
Claim 2
Independent Claim
158 words
A system for capacitive edge detection of a supported member comprising: a member where the position of an edge of said member is to be detected; a first probe positioned proximate to said member near the edge thereof and having a parameter varying as a function both of a distance from said probe to said member and displacement of a portion of said probe beyond the edge of said member; a second probe positioned near said first probe and closer to an interior location of said member than said first probe, said second probe having a parameter varying with distance of said second probe from said member; a first operational amplifier having the capacitance sensed by the electrode of the first probe in a feedback loop thereof; a second operational amplifier having the capacitance sensed by the electrode of the second probe in an input circuit thereof and; a source of A.C. excitation driving said first operational amplifier.
Claim 3
Dependent Claim
15 words
The system of claim 1 including means for supporting said member at the center thereof.
Claim 4
Dependent Claim
14 words
The system of claim 2 including means for rotating said member about its center.
Claim 5
Dependent Claim
33 words
The system of claim 3 further including means for repositioning said supported member on said support means in response to said indication of edge position to be more centered on said support means.
Claim 6
Dependent Claim
13 words
The system of claim 2 wherein said support means includes a vacuum chuck.
Claim 7
Dependent Claim
12 words
The system of claim 1 wherein said member is a semiconductor wafer.
Claim 8
Dependent Claim
14 words
The system of claim 1 wherein said first probe includes a capacitance sensing electrode.
Claim 9
Dependent Claim
14 words
The system of claim 7 wherein said second probe includes a capacitance sensing electrode.
Claim 10
Dependent Claim
25 words
The system of claim 8 wherein said first and second probe electrodes have a surface area facing said member of approximately the same effective area.
Claim 11
Dependent Claim
15 words
The system of claim 8 further including a guard around each said capacitance sensing electrode.
Claim 12
Dependent Claim
21 words
The system of claim 10 further including means for maintaining a virtually identical potential on each said guard and associated electrode.
Claim 13
Dependent Claim
21 words
The system of claim 1 further including a third operational amplifier connected to receive an output of said second operational amplifier.
Claim 14
Dependent Claim
23 words
The system of claim 12 further including a coupling between said second and third amplifiers compensating for errors sensed by said second probe.
Claim 15
Dependent Claim
31 words
The system of claim 1 further including means for compensating an output of said second operational amplifier for differences in distances between said member and said first and second probes respectively.
Claim 16
Independent Claim
110 words
A system for capacitively gauging distance comprising: a first capacitance sensing electrode spaced a distance from a member at a location adjacent to an edge thereof; a second capacitance sensing electrode spaced a distance from the member at location interior to the edge thereof; an operational amplifier connected to said first electrode; a source of A.C. excitation connected to said second electrode, said second electrode providing an output representative of distance from said second electrode to the member for input to a non-inverting input of said operational amplifier; said operational amplifier providing an output signal varying directly with the displacement of said first electrode from an edge of the member.
Claim 17
Independent Claim
110 words
A system for capacitively gauging distance comprising: a first capacitance sensing electrode spaced a distance from a member at a location adjacent to an edge thereof; a second capacitance sensing electrode spaced a distance from the member at location interior to the edge thereof; an operational amplifier connected to said first electrode; a source of A.C. excitation connected to said second electrode, said second electrode providing an output representative of distance from said second electrode to the member for input to a non-inverting input of said operational amplifier; said operational amplifier providing an output signal varying directly with the displacement of said first electrode from an edge of the member.
Claim 18
Dependent Claim
26 words
The system of claim 15 wherein said first electrode includes a guard and means for driving said guard at the virtual potential of said first electrode.
Claim 19
Dependent Claim
19 words
The system of claim 15 further including circuit means for compensating said output for effects attributable to stray capacitance.
Claim 20
Dependent Claim
25 words
The system of claim 15 further including circuit means for compensating said output for effects attributable to less than infinite gain of said operational amplifier.
Claim 21
Dependent Claim
85 words
An edge detection system comprising: first probe means at a first location for providing a first output representation of its distance from a member; second probe means at a second location for providing a second output representation of its distance from said member in combination with its displacement from an edge of said member; means for compensating said second output with an estimate of what said first output would be if said first output were provided at the second location of said second probe means.
Claim 22
Dependent Claim
85 words
An edge detection system comprising: first probe means at a first location for providing a first output representation of its distance from a member; second probe means at a second location for providing a second output representation of its distance from said member in combination with its displacement from an edge of said member; means for compensating said second output with an estimate of what said first output would be if said first output were provided at the second location of said second probe means.
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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) | 1993-09-17 | 1994-03-19 | 1994-09-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-17 | 1998-03-19 | 1998-09-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-17 | 2002-03-19 | 2002-09-18 | $7700.00 | Window Closed / Lapsed |