US4381952A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for fabricating a low loss varactor diode
Assignee: RCA Corp
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Filing: 1981-05-11
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Granted: 1983-05-03
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Expires: 2001-05-11
Abstract
Abstract A low conductivity, first conductivity type epitaxial layer is formed on a substrate of high conductivity, first conductivity type semiconductor material. Conductivity modifiers of second conductivity type are then implanted into the epitaxial layer so as to create a PN junction in the epitaxial layer. The substrate is next thinned, and conductivity modifiers of first conductivity type are implanted into the thinned surface so as to form a very high conductivity layer at the thinned surface.
Inventors
- 👤 Arye Rosen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 03:31
CPC Classifications
H; H10; H10P; H10P30/00; H10P30/20; H10P30/21; H10D; H10D1/00; H10D1/60; H10D1/62; H10D1/64; H10P30/202; H10P30/204; H10P30/28; H10P50/00; H10P50/60; H10P50/64; H10P50/642
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
104 words
A method for fabricating a low loss varactor diode, comprising the steps of: providing a high conductivity first conductivity type semiconductor substrate; epitaxially forming a low conductivity first conductivity type semiconductor layer on said substrate; implanting conductivity modifiers of second conductivity type into said epitaxial layer so as to form a very high conductivity layer at the surface thereof, said implanted layer forming a PN junction with said epitaxial layer; thinning the substrate so as to form a thinned surface; and implanting conductivity modifiers of first conductivity type into the thinned surface so as to form a very high conductivity layer at said surface.
Claim 2
Independent Claim
104 words
A method for fabricating a low loss varactor diode, comprising the steps of: providing a high conductivity first conductivity type semiconductor substrate; epitaxially forming a low conductivity first conductivity type semiconductor layer on said substrate; implanting conductivity modifiers of second conductivity type into said epitaxial layer so as to form a very high conductivity layer at the surface thereof, said implanted layer forming a PN junction with said epitaxial layer; thinning the substrate so as to form a thinned surface; and implanting conductivity modifiers of first conductivity type into the thinned surface so as to form a very high conductivity layer at said surface.
Claim 3
Dependent Claim
16 words
A method in accordance with claim 1, further comprising: annealing the structure following the implantation steps.
Claim 4
Dependent Claim
19 words
A method in accordance with claim 2, wherein the annealing following the second implantation is performed by laser irradiation.
Claim 5
Dependent Claim
22 words
A method in accordance with claim 1, further comprising: forming a first electrode on the epitaxial layer following the first implantation step.
Claim 6
Dependent Claim
21 words
A method in accordance with claim 1, further comprising: forming an electrode on said thinned surface following the second implantation step.
Claim 7
Independent Claim
31 words
A method in accordance with claims 4 or 5, wherein the electrode is formed by the steps of: sequentially evaporating chromium, platinum, and gold; and electroplating a relatively thick copper layer.
Claim 8
Dependent Claim
26 words
A method in accordance with claim 1, wherein the substrate is thinned by: etching the substrate in a mixture of 92% HNO 3 and 8% HF.
Claim 9
Dependent Claim
30 words
A method in accordance with claim 1, further comprising: forming the epitaxial layer with a carrier concentration of approximately 3×10 15 cm -3 and a thickness of approximately 6 microns.
Claim 10
Dependent Claim
26 words
A method in accordance with claim 8, further comprising: implanting at an energy level of 40-50 KeV and a dose of 1.5×10 15 cm -2 .
Claim 11
Dependent Claim
19 words
A method in accordance with claim 8, further comprising: thinning the substrate to a thickness of approximately 10 microns.
References Cited (Backward Citations)
US3523838A
Cited
US3638300A
Cited
US3878001A
Cited
US3634738A
Cited
US3840306A
Cited
US4038106A
Cited
US4106953A
Cited
US4250514A
Cited
US4226648A
Cited
US4230505A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-05-02 | 1986-11-01 | 1987-05-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-05-02 | 1990-11-01 | 1991-05-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-05-02 | 1994-11-01 | 1995-05-03 | $7700.00 | Window Closed / Lapsed |