Patent US4637726A successfully refreshed from Google Patents.
US4637726A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Nondestructive noncontact device to characterize semiconductor material
Assignee: United States Department of the Army
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Filing: 1985-02-07
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Granted: 1987-01-20
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Expires: 2005-02-07
Abstract
Abstract A wafer is positioned in a magnetic field. A computer initializes the light level and the electronic gain of each detector preamp associated with a fiber optic link from the analyzer. The magnetic field direction would then be reversed by computer command. This would cause a localized change in intensity of light passing through the wafer, due to Faraday Rotation (FR). The resulting change in detector output together with location and wavelength data could be used to compute a map of the wafer.
Inventors
- 👤 Clifford G. Walker
- 👤 George A. Tanton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 14:17
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/21; G01N2021/218; G01N21/84; G01N2021/8461; G01N21/86; G01N2021/8645; G01N2201/00; G01N2201/08
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
205 words
In a system for testing a device which will pass light therethrough, the improvement comprising a light source for producing light, a plurality of first fiber optics located between said light source and said device to be tested whereby light from said light source will be directed through said device to be tested in a plurality of different small areas of said device, a second plurality of second fiber optics positioned to individually receive light that passes through the different areas of said device to be tested, a plurality of detectors positioned to receive light form individual optical fibers of said second plurality of optical fibers so as to detect any change in the characteristics of the light cause by said device to be tested, a polarizer connected between said light source and said first plurality of optical fibers so as to polarize the light entering said second plurality of optical fibers and said device tested, magnetic means for providing a magnetic field across said device to be tested; and a polarizer analyzer positioned between said device to be detected and said second plurality of optical fibers whereby any Faraday rotation (FR) caused by said device to be tested will be detected by said detectors.
Claim 2
Dependent Claim
205 words
In a system for testing a device which will pass light therethrough, the improvement comprising a light source for producing light, a plurality of first fiber optics located between said light source and said device to be tested whereby light from said light source will be directed through said device to be tested in a plurality of different small areas of said device, a second plurality of second fiber optics positioned to individually receive light that passes through the different areas of said device to be tested, a plurality of detectors positioned to receive light form individual optical fibers of said second plurality of optical fibers so as to detect any change in the characteristics of the light cause by said device to be tested, a polarizer connected between said light source and said first plurality of optical fibers so as to polarize the light entering said second plurality of optical fibers and said device tested, magnetic means for providing a magnetic field across said device to be tested; and a polarizer analyzer positioned between said device to be detected and said second plurality of optical fibers whereby any Faraday rotation (FR) caused by said device to be tested will be detected by said detectors.
Claim 3
Dependent Claim
31 words
A system as set forth in claim 1 further comprising a selector means connected to said plurality of detectors so as to individually select and record the outputs of the detectors.
Claim 4
Dependent Claim
66 words
A system as set forth in claim 2 further comprising a controller and processor connected to said selector means for the determining which detector is to be selected and for storing the information detected, and said controller and processor connected to said magnetic means for reversing the magnetic field so as to provide a reverse FR reading of each area of said device to be detected.
Claim 5
Dependent Claim
52 words
A device as set forth in claim 3 further comprising a chopper positioned between said light source and said polarizers so as to pulse the output of said light source; and synchronizing means connected between said chopper, selector means and said controller and processor for synchronizing the selected outputs of the detectors.
Claim 6
Dependent Claim
54 words
A system as set forth in claim 4 further comprising a wavelength selector positioned between said light source and said chopper for determining the wavelength of the light to be passed through said device to be tested, and means connected to said wavelength selector and said controller and processor for controlling said wavelength selector.
Claim 7
Dependent Claim
40 words
A system as set forth in claim 5 whereby the controller processor in cooperation with the selector means provides a map of the device to be tested and an output display connected to the controller processor for displaying said map.
Claim 8
Dependent Claim
122 words
In a system for testing a device which will cause Faraday rotation (FR) of polarized light passing therethrough, the improvement comprising a light source for producing polarized light, a first means located between said light source and said device to be tested whereby light from said light source will be directed through said device to be tested, magnetic means positioned so as to produce a magnetic field through said device to be detected so as to cause FR of the polarized light passing through said device, and a plurality of detectors positioned to receive light from individual small areas of said device so as to detect any change in the characteristics of the polarized light cause by said device to be tested.
Claim 9
Dependent Claim
122 words
In a system for testing a device which will cause Faraday rotation (FR) of polarized light passing therethrough, the improvement comprising a light source for producing polarized light, a first means located between said light source and said device to be tested whereby light from said light source will be directed through said device to be tested, magnetic means positioned so as to produce a magnetic field through said device to be detected so as to cause FR of the polarized light passing through said device, and a plurality of detectors positioned to receive light from individual small areas of said device so as to detect any change in the characteristics of the polarized light cause by said device to be tested.
Claim 10
Dependent Claim
29 words
A system as set forth in claim 7 further comprising a controller means connected to said magnetic means so as to selectively reverse the direction of the magnetic field.
Claim 11
Dependent Claim
23 words
A system as set forth in claim 8 further comprising a polarizer analyzer positioned between said device to be detected and said detectors.
Claim 12
Dependent Claim
18 words
A system as set forth in claim 8 further comprising a conventional means for lowering the wafer temperature.
References Cited (Backward Citations)
US4498780A
Cited
US4559451A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-01-19 | 1990-07-21 | 1991-01-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-01-19 | 1994-07-21 | 1995-01-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-01-19 | 1998-07-21 | 1999-01-20 | $7700.00 | Window Closed / Lapsed |