US4777146A
Expired / Lapsed
US
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Fabrication process involving semi-insulating material
Assignee: Nokia Bell Labs
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Filing: 1987-02-24
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Granted: 1988-10-11
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Expires: 2007-02-24
Abstract
Abstract Semi-insulating wafers such as semi-insulating gallium arsenide wafers are commonly utilized in the fabrication of semiconductor devices, e.g., lasers and optical detectors. The quality of wafer electrical properties is determined before device processing by an optical technique. In this technique a refractive index change is induced with incident light and the rate of decay of this refractive index change upon change of incident light intensity is monitored with a second beam. The rate of decay is directly related to electrical properties such as resistivity. Subsequent processing is then based on this measurement.
Inventors
- 👤 Richard B. Bylsma
- 👤 Alastair M. Glass
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 01:34
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/26; G01R31/265; G01R31/2656; G01N; G01N21/00; G01N21/62; G01N21/63
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
91 words
A process for preparing a body comprising semi-insulating material, said process comprising the steps of (1) fabricating said semi-insulating body, (2) inducing with electromagnetic radiation a first refractive index profile in said material that differs from the unilluminated refractive index profile of said material, (3) changing the intensity of said electromagnetic radiation to cause a change in said first refractive index profile, (4) monitoring said change with electromagnetic radiation, (5) determining from the result of said monitoring the suitability of said body, and (6) employing said body based on said determination.
Claim 2
Dependent Claim
91 words
A process for preparing a body comprising semi-insulating material, said process comprising the steps of (1) fabricating said semi-insulating body, (2) inducing with electromagnetic radiation a first refractive index profile in said material that differs from the unilluminated refractive index profile of said material, (3) changing the intensity of said electromagnetic radiation to cause a change in said first refractive index profile, (4) monitoring said change with electromagnetic radiation, (5) determining from the result of said monitoring the suitability of said body, and (6) employing said body based on said determination.
Claim 3
Dependent Claim
17 words
The process of claim 1 wherein said body comprises a material having a zinc blende crystal structure.
Claim 4
Dependent Claim
11 words
The process of claim 1 wherein said body comprises gallium arsenide.
Claim 5
Dependent Claim
15 words
The process of claim 1 wherein said first refractive index profile comprises a diffraction grating.
Claim 6
Dependent Claim
12 words
The process of claim 1 wherein said electromagnetic radiation comprises laser light.
Claim 7
Dependent Claim
18 words
The process of claim 1 wherein said change in intensity comprises a termination of said inducing electromagnetic radiation.
Claim 8
Dependent Claim
12 words
The process of claim 3 where said body comprises doped gallium arsenide.
Claim 9
Dependent Claim
12 words
The process of claim 4 wherein said electromagnetic radiation comprises laser light.
Claim 10
Dependent Claim
18 words
The process of claim 8 wherein said change in intensity comprises a termination of said inducing electromagnetic radiation.
Claim 11
Dependent Claim
95 words
A process for fabricating a plurality of devices comprising the steps of (1) preparing a wafer comprising a semi-insulating material, (2) inducing with electomagnetic radiation a first refractive index profile in a region of said wafer that differs from the unilluminated refractive index profile of said material, (3) changing the intensity of said electromagnetic radiation to cause a change in said refractive index profile, (4) monitoring said change with electromagnetic radiation, (5) determining from the result of said monitoring the suitably of said wafer, and (6) completing said plurality of devices on said suitable wafer.
Claim 12
Dependent Claim
95 words
A process for fabricating a plurality of devices comprising the steps of (1) preparing a wafer comprising a semi-insulating material, (2) inducing with electomagnetic radiation a first refractive index profile in a region of said wafer that differs from the unilluminated refractive index profile of said material, (3) changing the intensity of said electromagnetic radiation to cause a change in said refractive index profile, (4) monitoring said change with electromagnetic radiation, (5) determining from the result of said monitoring the suitably of said wafer, and (6) completing said plurality of devices on said suitable wafer.
Claim 13
Dependent Claim
17 words
The process of claim 10 wherein said body comprises a material having a zinc blende crystal structure.
Claim 14
Dependent Claim
10 words
The process of claim 10 wherein said body comprises GaAs.
Claim 15
Dependent Claim
15 words
The process of claim 10 wherein said first refractive index profile comprises a diffraction grating.
Claim 16
Dependent Claim
12 words
The process of claim 10 wherein said electromagnetic radiation comprises laser light.
Claim 17
Dependent Claim
18 words
The process of claim 10 wherein said change in intensity comprises a termination of said inducing electromagnetic radiation.
Claim 18
Dependent Claim
27 words
The process of claim 10 wherein said wafer is representative of a plurality of wafers and said devices on said wafers are completed based on said determination.
Claim 19
Dependent Claim
12 words
The process of claim 12 wherein said body comprises doped gallium arsenide.
Claim 20
Dependent Claim
12 words
The process of claim 14 wherein said electromagnetic radiation comprises laser light.
Claim 21
Dependent Claim
18 words
The process of claim 18 wherein said change in intensity comprises a termination of said inducing electromagnetic radiation.
Claim 22
Dependent Claim
79 words
A process for preparing a body comprising semi-insulating material, said process comprising the steps of (1) fabricating said body, (2) inducing with electromagnetic radiation an absorption that differs from the unilluminated absorption of said material, (3) changing the intensity of said electromagnetic radiation to cause a change in said absorption, (4) monitoring said change with electromagnetic radiation, (5) determining from the result of said monitoring the suitability of said boedy, and (6) employing said body based on said determination.
Claim 23
Dependent Claim
79 words
A process for preparing a body comprising semi-insulating material, said process comprising the steps of (1) fabricating said body, (2) inducing with electromagnetic radiation an absorption that differs from the unilluminated absorption of said material, (3) changing the intensity of said electromagnetic radiation to cause a change in said absorption, (4) monitoring said change with electromagnetic radiation, (5) determining from the result of said monitoring the suitability of said boedy, and (6) employing said body based on said determination.
Claim 24
Dependent Claim
16 words
The process of claim 20 wherein said body comprises a semi-insulating layer formed on a wafer.
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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) | 1991-10-11 | 1992-04-11 | 1992-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-11 | 1996-04-11 | 1996-10-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-11 | 2000-04-11 | 2000-10-11 | $7700.00 | Window Closed / Lapsed |