US4044373A
Expired / Lapsed
US
⏱️ 0.0 years remaining
IGFET with gate protection diode and antiparasitic isolation means
Assignee: Hitachi Ltd
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Filing: 1973-06-12
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Granted: 1977-08-23
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Expires: 1993-06-12
Abstract
Abstract Described are insulated gate-type field effect transistors used in capacitive memory circuits and having protective diodes for protecting the insulating films below the gate electrodes from electrical breakdown, in which parasitic transistor action which might be caused by minority carriers injected into semiconductor substrates by noise signals applied to the protective diodes are eliminated by means for suppressing injection of minority carriers or by means for preventing injected minority carriers from reaching the drain regions of the field effect transistors.
Inventors
- 👤 Kosei Nomiya
- 👤 Toshihiko Kohisa
- 👤 Isao Matsumura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 12:50
CPC Classifications
H; H10; H10W; H10W10/00; G; G11; G11C; G11C19/00; G11C19/18; G11C19/182; G11C19/184; H03; H03K; H03K17/00; H03K17/08; H03K17/081; H03K17/0812; H03K17/08122; H10D; H10D84/00; H10D84/40; H10D84/401; H10D84/403; H10D84/409; H10D89/00; H10D89/60; H10D89/601; H10W10/01; H10W10/021; H10W10/031; H10W10/20; H10W10/30
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
262 words
In a semiconductor device comprising: an insulated gate type field effect element including a semiconductor substrate of first conductivity type, a pair of source and drain regions of second conductivity type opposite to said first conductivity type formed in a surface of said semiconductor substrate, an insulated gate electrode disposed on said surface between said source and drain regions, and an insulating film interposed between said insulated gate electrode and said semiconductor substrate; a protecting diode means formed unitarily with said field effect element and connected in parallel between said insulated gate electrode and said semiconductor substrate for preventing the insulating film below said gate electrode from breakdown, said protecting diode means including a semiconductor region and an electrode means with a rectifying barrier disposed therebetween, said rectifying barrier having a backward breakdown voltage lower than the breakdown voltage of the insulating film below said gate electrode; the improvement comprising isolation means for electrically isolating said semiconductor region of said protecting diode means from said semiconductor substrate in which said field effect element is formed; and wherein the conductivity type of said semiconductor region of said protecting diode means is said first conductivity type, and said isolation means includes a semiconductor layer of said second conductivity type interposed between said semiconductor region of said protecting diode means and said semiconductor substrate; and wherein said semiconductor layer is biased in the backward polarity to said semiconductor region of said protecting diode means and said semiconductor substrate; and wherein the semiconductor region of said protecting diode means is connected together with said semiconductor substrate.
Claim 2
Dependent Claim
262 words
In a semiconductor device comprising: an insulated gate type field effect element including a semiconductor substrate of first conductivity type, a pair of source and drain regions of second conductivity type opposite to said first conductivity type formed in a surface of said semiconductor substrate, an insulated gate electrode disposed on said surface between said source and drain regions, and an insulating film interposed between said insulated gate electrode and said semiconductor substrate; a protecting diode means formed unitarily with said field effect element and connected in parallel between said insulated gate electrode and said semiconductor substrate for preventing the insulating film below said gate electrode from breakdown, said protecting diode means including a semiconductor region and an electrode means with a rectifying barrier disposed therebetween, said rectifying barrier having a backward breakdown voltage lower than the breakdown voltage of the insulating film below said gate electrode; the improvement comprising isolation means for electrically isolating said semiconductor region of said protecting diode means from said semiconductor substrate in which said field effect element is formed; and wherein the conductivity type of said semiconductor region of said protecting diode means is said first conductivity type, and said isolation means includes a semiconductor layer of said second conductivity type interposed between said semiconductor region of said protecting diode means and said semiconductor substrate; and wherein said semiconductor layer is biased in the backward polarity to said semiconductor region of said protecting diode means and said semiconductor substrate; and wherein the semiconductor region of said protecting diode means is connected together with said semiconductor substrate.
Claim 3
Dependent Claim
202 words
A semiconductor device comprising: a semiconductor substrate of first conductivity type; an insulated gate type field effect element including a pair of source and drain regions of second conductivity type opposite to said first conductivity type formed in a surface of said semiconductor substrate, an insulated gate electrode disposed on said surface between said source and drain regions, and an insulating film interposed between said insulated gate electrode and said semiconductor substrate; a protective diode means including a terminal region formed in said surface of said semiconductor substrate with a rectifying barrier disposed between said terminal region of the protective diode means and said semiconductor substrate, said rectifying barrier having a backward breakdown voltage lower than a voltage which causes the insulating film below said gate electrode to breakdown; an auxiliary semiconductor region of said second conductivity type formed in said surface of said semiconductor substrate and disposed between said field effect element and said terminal region of the protecting diode means for preventing minority carriers injected through said rectifying barrier of said protecting diode means into said semiconductor substrate from reaching said drain region; and conductive means for connecting the terminal region of said protecting diode with said insulated gate electrode.
Claim 4
Dependent Claim
202 words
A semiconductor device comprising: a semiconductor substrate of first conductivity type; an insulated gate type field effect element including a pair of source and drain regions of second conductivity type opposite to said first conductivity type formed in a surface of said semiconductor substrate, an insulated gate electrode disposed on said surface between said source and drain regions, and an insulating film interposed between said insulated gate electrode and said semiconductor substrate; a protective diode means including a terminal region formed in said surface of said semiconductor substrate with a rectifying barrier disposed between said terminal region of the protective diode means and said semiconductor substrate, said rectifying barrier having a backward breakdown voltage lower than a voltage which causes the insulating film below said gate electrode to breakdown; an auxiliary semiconductor region of said second conductivity type formed in said surface of said semiconductor substrate and disposed between said field effect element and said terminal region of the protecting diode means for preventing minority carriers injected through said rectifying barrier of said protecting diode means into said semiconductor substrate from reaching said drain region; and conductive means for connecting the terminal region of said protecting diode with said insulated gate electrode.
Claim 5
Dependent Claim
25 words
The semiconductor device of claim 2, wherein the PN junction between said auxiliary semiconductor region and said semiconductor substrate is biased in the backward direction.
Claim 6
Dependent Claim
35 words
The semiconductor device of claim 2, further comprising a high conductivity semiconductor region of said first conductivity type lying at least under said terminal region of said protecting diode means and said auxiliary semiconductor region.
Claim 7
Dependent Claim
18 words
The semiconductor device of claim 4, wherein said auxiliary semiconductor region contacts with said high conductivity semiconductor region.
Claim 8
Dependent Claim
51 words
The semiconductor device of claim 4, wherein said auxiliary semiconductor region is spaced from said high conductivity semiconductor region, and the PN junction between said auxiliary semiconductor region and said semiconductor substrate is biased so that the depletion layer extending from said PN junction contacts with said high conductivity semiconductor region.
Claim 9
Dependent Claim
20 words
The semiconductor device of claim 2, further comprising a capacitor means connected between said semiconductor substrate and said drain region.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-08-22 | 1981-02-21 | 1981-08-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-22 | 1985-02-21 | 1985-08-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-22 | 1989-02-21 | 1989-08-23 | $7700.00 | Window Closed / Lapsed |