US4398342A
Expired / Lapsed
US
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Method of making a Hall effect device
Assignee: STC PLC
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Filing: 1982-02-22
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Granted: 1983-08-16
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Expires: 2002-02-22
Abstract
Abstract A Hall effect device comprises a thin substrate free epitaxially grown semiconductor body mounted in a magnetically permeable, e.g. ferrite, housing. The layer, which is preferably gallium arsenide or gallium indium arsenide, is grown on a substrate which, after device processing is complete, is removed by a selective etching process. In view of the relatively high sensitivity and good noise characteristics such a device with its flux concentrator is small, since the flux concentrators are themselves much smaller than with conventional Hall effect systems. Other semiconductor materials from which the novel thin Hall effect devices can be made include silicon.
Inventors
- 👤 Gillies D. Pitt
- 👤 Peter D. Greene
- 👤 Edward J. Thrush
- 👤 David H. Whysall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 20:01
CPC Classifications
H; H10; H10N; H10N52/00; H10N52/01; H10W; H10W90/00; H10W90/701; H10W90/721; H10W90/724
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
147 words
A method of making an improved Hall-effect device assembly comprising: providing a substrate with an epitaxial layer, having Hall electrodes thereon, and an intervening barrier layer between said substrate and said epitaxial layer, wherein said barrier layer has a composition different from said epitaxial layer and said substrate; removing said substrate to form a Hall-effect device by dissolving said substrate with an etchant, wherein said etchant and said barrier layer are substantially non-reactive; mounting said Hall-effect device in a space provided by disposing the substantially planar ends of two flux concentrator rods in substantially parallel facing relationship; attaching leads in conducting relationship with said Hall-electrodes; and encapsulating said Hall-effect device and said ends of said rods in a body of potting compound with said Hall-effect device disposed in said space substantially parallel to said rod ends and said leads extending externally of said body of potting compound.
Claim 2
Independent Claim
147 words
A method of making an improved Hall-effect device assembly comprising: providing a substrate with an epitaxial layer, having Hall electrodes thereon, and an intervening barrier layer between said substrate and said epitaxial layer, wherein said barrier layer has a composition different from said epitaxial layer and said substrate; removing said substrate to form a Hall-effect device by dissolving said substrate with an etchant, wherein said etchant and said barrier layer are substantially non-reactive; mounting said Hall-effect device in a space provided by disposing the substantially planar ends of two flux concentrator rods in substantially parallel facing relationship; attaching leads in conducting relationship with said Hall-electrodes; and encapsulating said Hall-effect device and said ends of said rods in a body of potting compound with said Hall-effect device disposed in said space substantially parallel to said rod ends and said leads extending externally of said body of potting compound.
Claim 3
Dependent Claim
54 words
The method recited in claim 1 wherein: said epitaxial layer is gallium arsenide; said barrier layer is gallium aluminum arsenide having the formula Ga 1-x Al x As where 0.8>x>0.5; and said etchant comprises a mixture of a 30% aqueous solution of 95% H 2 O 2 and a 5% concentrated NH 3 solution.
Claim 4
Dependent Claim
33 words
The method recited in claim 1 or 2 further including the step of removing said intervening barrier layer, using an etchant that is substantially non-reactive with said epitaxial layer, after removing said substrate.
Claim 5
Dependent Claim
21 words
The method recited in claim 3 wherein said etchant used to remove said intervening barrier layer is a concentrated HF solution.
Claim 6
Dependent Claim
22 words
The method recited in claim 1 or 2 further including the step of depositing said epitaxial layer by metalorganic chemical vapor deposition.
Claim 7
Dependent Claim
29 words
The method recited in claim 1 wherein said Hall-effect device is mounted to the substantially planar end of one of said rods prior to encapsulation in said potting compound.
Claim 8
Dependent Claim
72 words
The method recited in claim 6 wherein: said leads include a conductive pattern formed on the end of said one rod and lead extensions connected to said conductive pattern extending beyond the periphery of said one rod and externally of said body of potting compound; and said Hall-effect device is mounted with said Hall electrodes in contact with said conductive pattern to provide the current and sensing circuits for said Hall-effect device.
Claim 9
Dependent Claim
18 words
The method recited in claim 7 wherein said lead extensions are supported by a non-magnetic, electrically insulating material.
Claim 10
Dependent Claim
24 words
The method recited in claim 7 wherein said Hall-effect device is mounted on the end of said one rod prior to removing said substrate.
Claim 11
Dependent Claim
76 words
The method recited in claim 6 wherein: said Hall-effect device is mounted on a substantially planar platform; and said leads include a conductive pattern formed on the surface of said platform and lead extensions extending from said platform and externally of said body of potting compound, wherein said Hall-effect device is mounted on said platform with said Hall electrodes in contact with said conductive pattern to provide the current and sensing circuits for said Hall-effect device.
Claim 12
Dependent Claim
39 words
The method recited in claim 10 wherein said lead extensions include a supporting portion that cooperate with the end of said one rod to hold said platform in said space prior to encapsulation in said body of potting compound.
Claim 13
Dependent Claim
64 words
The method recited in claim 1, 2, 6, 7, 8, 9, 10 or 11 wherein: said Hall-effect device is substantially square with sides no longer than 0.5 mm and no thicker than 10 μm; said space is no greater than 0.3 mm; and said rods have a round cross-section no greater than 1.1 mm in diameter and are no greater than 20 mm long.
Claim 14
Dependent Claim
39 words
The method recited in claim 12 wherein: said Hall-effect device has sides about 0.5 mm long and is about 1 μm thick; said space is 10 μm; and said rods are 8 mm long and 0.5 mm in diameter.
Claim 15
Dependent Claim
19 words
The method recited in claim 1, 2, 6, 7, 8, 9, 10 or 11 wherein said rods are metallic-glass.
References Cited (Backward Citations)
US3845445A
Cited
US4021767A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-08-15 | 1987-02-14 | 1987-08-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-15 | 1991-02-14 | 1991-08-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-15 | 1995-02-14 | 1995-08-16 | $7700.00 | Window Closed / Lapsed |