Patent US3891479A successfully refreshed from Google Patents.
US3891479A
Expired / Lapsed
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Method of making a high current Schottky barrier device
Assignee: Motorola Solutions Inc
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Filing: 1973-03-12
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Granted: 1975-06-24
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Expires: 1993-03-12
Abstract
Abstract A heavily doped N type conductivity substrate having a lightly doped N type conductivity epitaxial layer grown thereon with a centrally located buried layer diffused therein and a second lightly doped N type conductivity epitaxial layer grown on the first layer with a P type conductivity guardring diffused therein. The guardring is generally coaxial with the buried layer and a layer of metal is deposited on the surface of the second epitaxial layer to form a Schottky barrier device with the guardring lying generally below the periphery thereof. The buried layer extends upwardly within the guardring to provide a substantially uniform or constant thickness of lightly doped semiconductive material between the junction of the device and the heavily doped substrate.
Inventors
- 👤 Ross Zwernemann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:24
CPC Classifications
H; H10; H10D; H10D8/00; H10D8/60; H10D62/00; H10D62/10; Y; Y10; Y10S; Y10S148/00; Y10S148/037; Y10S148/139; Y10S148/145
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
220 words
A METHOD OF CONSTRUCTING IMPROVED HIGH CURRENT SCHOTTKY BARRIER DEVICES INCLUDING THE STEPS OF: A. GROWING A FIRST EPITAXIAL LAYER, WITH A RELATIVELY LIGHT CONCENTRATION OF IMPURITIES FOR PROVIDING CONDUCTIVITY OF A FIRST TYPE, ON A SUBSTRATE LAYER WITH A RELATIVELY HEAVY CONCENTRATION OF IMPURITIES FOR PROVIDING CONDUCTIVITY OF THE FIRST TYPE; B. DIFFUSING A RELATIVELY HEAVY CONCENTRATION OF IMPURITIES INTO A CENTRAL PORTION OF SAID FIRST EPITAXIAL LAYER FOR PROVIDING CONDUCTIVITY OF THE FIRST TYPE, SAID CENTRAL PORTION EXTENDING THROUGH SAID FIRST EPITAXIAL LAYER INTO CONTACT WITH SAID SUBSTRATE LAYER; C. GROWING A SECOND EPITAXIAL LAYER, WITH A RELATIVELY LIGHT CONCENTRATION OF IMPURITIES FOR PROVIDING CONDUCTIVITY OF A FIRST TYPE, ON SAID FIRST EPITAXIAL LAYER; D. DIFFUSING A GUARDRING OF IMPURITIES, FOR PROVIDING CONDUCTIVITY OF A SECOND TYPE, ON SAID FIRST EPITAXIAL LAYER IN A RELATIVELY LIGHT CONCENTRATION AND SUBSTANTIALLY EQUALLY SPACED ABOUT SAID CENTRAL PORTION OF SAID FIRST EPITAXIAL LAYER; E. DEPOSITING A LAYER OF INSULATING MATERIAL ON THE SURFACE OF SAID SECOND EPITAXIAL LAYER ANDD FORMING AN APERTURE THERETHROUGH HAVING AN OUTER PERIPHERY LOCATED GENERALLY ABOVE AND COEXTENSIVE WITH SAID GUARDRING, AND EXPOSING A PORTION OF THE SURFACE OF THE SECOND EPITAXIAL LAYER; AND F. DEPOSITING BARRIER AND CONTACT METALS ON THE EXPOSED PORTION OF THE SURFACE OF THE SECOND EPITAXIAL LAYER TO FORM A SCHOTTKY BARRIER.
Claim 2
Independent Claim
220 words
A METHOD OF CONSTRUCTING IMPROVED HIGH CURRENT SCHOTTKY BARRIER DEVICES INCLUDING THE STEPS OF: A. GROWING A FIRST EPITAXIAL LAYER, WITH A RELATIVELY LIGHT CONCENTRATION OF IMPURITIES FOR PROVIDING CONDUCTIVITY OF A FIRST TYPE, ON A SUBSTRATE LAYER WITH A RELATIVELY HEAVY CONCENTRATION OF IMPURITIES FOR PROVIDING CONDUCTIVITY OF THE FIRST TYPE; B. DIFFUSING A RELATIVELY HEAVY CONCENTRATION OF IMPURITIES INTO A CENTRAL PORTION OF SAID FIRST EPITAXIAL LAYER FOR PROVIDING CONDUCTIVITY OF THE FIRST TYPE, SAID CENTRAL PORTION EXTENDING THROUGH SAID FIRST EPITAXIAL LAYER INTO CONTACT WITH SAID SUBSTRATE LAYER; C. GROWING A SECOND EPITAXIAL LAYER, WITH A RELATIVELY LIGHT CONCENTRATION OF IMPURITIES FOR PROVIDING CONDUCTIVITY OF A FIRST TYPE, ON SAID FIRST EPITAXIAL LAYER; D. DIFFUSING A GUARDRING OF IMPURITIES, FOR PROVIDING CONDUCTIVITY OF A SECOND TYPE, ON SAID FIRST EPITAXIAL LAYER IN A RELATIVELY LIGHT CONCENTRATION AND SUBSTANTIALLY EQUALLY SPACED ABOUT SAID CENTRAL PORTION OF SAID FIRST EPITAXIAL LAYER; E. DEPOSITING A LAYER OF INSULATING MATERIAL ON THE SURFACE OF SAID SECOND EPITAXIAL LAYER ANDD FORMING AN APERTURE THERETHROUGH HAVING AN OUTER PERIPHERY LOCATED GENERALLY ABOVE AND COEXTENSIVE WITH SAID GUARDRING, AND EXPOSING A PORTION OF THE SURFACE OF THE SECOND EPITAXIAL LAYER; AND F. DEPOSITING BARRIER AND CONTACT METALS ON THE EXPOSED PORTION OF THE SURFACE OF THE SECOND EPITAXIAL LAYER TO FORM A SCHOTTKY BARRIER.
Claim 3
Dependent Claim
46 words
A method as set forth in claim 1 wherein the said guardring of impurities are diffused into the central portion of the second epitaxial layer so that the guardring is approximately equidistant from said central portion of the first epitaxial layer and from the substrate layer.
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) | 1978-06-23 | 1978-12-23 | 1979-06-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-23 | 1982-12-23 | 1983-06-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-23 | 1986-12-23 | 1987-06-24 | $7700.00 | Window Closed / Lapsed |