Patent US4298403A successfully refreshed from Google Patents.
US4298403A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ion-implanted evaporated germanium layers as n+ contacts to GaAs
Assignee: Individual
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Filing: 1980-02-28
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Granted: 1981-11-03
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Expires: 2000-02-28
Abstract
Abstract A method of forming a single, reliable n + contact for discrete GaAs devices. A film of p-type Ge is deposited uniformly over the surface of a n-type GaAs substrate. Ions of phosphorous or arsenic are implanted to 5×10 18 ions/cc at a depth of 1500 A. The ends and the sides of the substrate and Ge layer are capped by a CVD oxide and annealed at 450°-500° C. for about one hour. This process over-compensates the initial p-type layers which results in the Ge layer becoming n + . The oxide is removed by an etch process and the n + Ge is etched to form two separate contact sections of n + Ge. The n + Ge is then metalized to form ohmic contacts by use of NiAu. A CVD oxide overcoat may again be applied and annealed at about 500° C. to drive a shallow 200-500 A, n + germanium diffusion into the substrate.
Inventors
- 👤 John E. Davey
- 👤 Aristos Christou
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 08:37
CPC Classifications
H; H10; H10P; H10P30/00; H10P30/20; H10P30/21; H10D; H10D62/00; H10D62/80; H10D62/85; H10D64/00; H10D64/01; H10D64/011; H10D64/0116; H10D64/60; H10D64/62; H10P30/202; H10P30/206; H10P30/28; Y; Y10; Y10S; Y10S438/00; Y10S438/902; Y10S438/914; Y10S438/919
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
114 words
A method for forming n + contacts for GaAs devices which comprises: depositing a p-type Ge film onto a GaAs substrate, implanting ions of arsenic or phosphorous into said Ge film to a desired depth, capping said Ge film on the top and sides and on the sides of the GaAs substrate with an oxide, annealing said capped Ge film-GaAs substrate in an inert gas ambient at a sufficient temperature over a sufficient time period to over-compensate the p-type Ge layer to change the p-type layer to an n + layer, removing the oxide cap, etching said n + Ge film to form contact areas, and depositing an ohmic metallization on the contact areas.
Claim 2
Independent Claim
114 words
A method for forming n + contacts for GaAs devices which comprises: depositing a p-type Ge film onto a GaAs substrate, implanting ions of arsenic or phosphorous into said Ge film to a desired depth, capping said Ge film on the top and sides and on the sides of the GaAs substrate with an oxide, annealing said capped Ge film-GaAs substrate in an inert gas ambient at a sufficient temperature over a sufficient time period to over-compensate the p-type Ge layer to change the p-type layer to an n + layer, removing the oxide cap, etching said n + Ge film to form contact areas, and depositing an ohmic metallization on the contact areas.
Claim 3
Dependent Claim
31 words
A method as claimed in claim 1 in which: said GaAs substrate is desorbed at a temperature of about 575° C. for about 15 minutes prior to depositing said Ge film.
Claim 4
Dependent Claim
28 words
A method as claimed in claim 2 in which: said Ge film is deposited to a thickness of about 3000 A at a temperature of about 475° C.
Claim 5
Dependent Claim
26 words
A method as claimed in claim 3 in which: said ions are implanted at a depth of 1500 A with a dosage of 5×10 18 ions/cc.
Claim 6
Dependent Claim
41 words
A method as claimed in claim 3 in which: said capped Ge film-GaAs substrte is annealed at a temperature of from about 450° C. to about 500° C. for about one hour to convert said p-type Ge to n + .
Claim 7
Dependent Claim
41 words
A method as claimed in claim 4 in which: said capped Ge film-GaAs substrte is annealed at a temperature of from about 450° C. to about 500° C. for about one hour to convert said p-type Ge to n + .
Claim 8
Dependent Claim
27 words
A method as claimed in claim 5 in which: said ohmic metallization on said contact areas are selected from a group consisting of AuNi, Au, and Ni.
Claim 9
Dependent Claim
17 words
A method as claimed in claim 6 in which: gold contacts are deposited onto said contact areas.
Claim 10
Dependent Claim
17 words
A method as claimed in claim 6 in which: nickel contacts are deposited onto said contact areas.
Claim 11
Dependent Claim
17 words
A method as claimed in claim 6 in which: AuNi contacts are deposited onto said contact areas.
Claim 12
Dependent Claim
75 words
A method as claimed in claim 1 in which: a CVD oxide cap is deposited over the said contacts and the periphery of said GaAs device, and said capped GaAs device is annealed at a temperature of about 500° C. for a time period of about one hour to drive a shallow 200-500 A n + germanium diffusion into said GaAs substrate, and removing the oxide cap previously applied over the contacts and GaAs device.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-11-02 | 1985-05-04 | 1985-11-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-11-02 | 1989-05-04 | 1989-11-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-11-02 | 1993-05-04 | 1993-11-03 | $7700.00 | Window Closed / Lapsed |