US4672403A
Expired / Lapsed
US
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Lateral subsurface zener diode
Assignee: National Semiconductor Corp
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Filing: 1985-09-23
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Granted: 1987-06-09
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Expires: 2005-09-23
Abstract
Abstract A subsurface zener diode is formed in an N type semiconductor substrate such as the kind employed in the epitaxial layer found in silicon monolithic PN junction isolated integrated circuits. A P+ anode is ion implanted into and diffused from an oxide source and an N++ cathode is diffused within the confines of the anode. The cathode is surrounded with a counter-doped region that forces the PN junction breakdown subsurface. The resulting diode has a clean, sharp breakdown curve and the breakdown voltage can be tailored by controlling the anode deposition.
Inventors
- 👤 Dean C. Jennings
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 23:15
CPC Classifications
H; H10; H10D; H10D8/00; H10D8/20; H10D8/25; H10D62/00; H10D62/10; H10D62/124; H10D62/126
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
153 words
A zener diode comprising: an anode comprising a P region extending into an N type substrate and forming a PN junction therewith that extends to a surface of said substrate; a cathode comprising an N region extending part way through said anode and forming a PN junction therewith that extends to said surface of said substrate; a counter-doped region surrounding said cathode and extending from said surface into said anode to a lesser extent than said cathode, said counter-doped region containing N type impurities in a concentration that will raise the resistivity of said anode but will be insufficient to convert said anode region to N type conductivity, whereby the PN junction that exists between said anode and said cathode has a breakdown region that lies just under said counter-doped region so that said breakdown region is located below said surface; and means for making electrical contact to said anode and said cathode.
Claim 2
Dependent Claim
153 words
A zener diode comprising: an anode comprising a P region extending into an N type substrate and forming a PN junction therewith that extends to a surface of said substrate; a cathode comprising an N region extending part way through said anode and forming a PN junction therewith that extends to said surface of said substrate; a counter-doped region surrounding said cathode and extending from said surface into said anode to a lesser extent than said cathode, said counter-doped region containing N type impurities in a concentration that will raise the resistivity of said anode but will be insufficient to convert said anode region to N type conductivity, whereby the PN junction that exists between said anode and said cathode has a breakdown region that lies just under said counter-doped region so that said breakdown region is located below said surface; and means for making electrical contact to said anode and said cathode.
Claim 3
Dependent Claim
28 words
A zener diode of claim 1 wherein the topography of said cathode includes a portion having a small radius of curvature whereby said breakdown is localized and initiated.
Claim 4
Dependent Claim
22 words
The zener diode of claim 1 wherein said breakdown occurs at a voltage determined primarily by the doping level of said anode.
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) | 1990-06-08 | 1990-12-08 | 1991-06-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-08 | 1994-12-08 | 1995-06-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-08 | 1998-12-08 | 1999-06-09 | $7700.00 | Window Closed / Lapsed |