Patent US4903099A successfully refreshed from Google Patents.
US4903099A
Expired / Lapsed
US
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Field effect transistor for use as ion sensor
Assignee: Nihon Kohden Corp
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Filing: 1988-09-28
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Granted: 1990-02-20
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Expires: 2008-09-28
Abstract
Abstract A field effect transistor for use as an ion sensor has a P-type silicon substrate on which are formed a source region and a drain region. An N-type isolation diffusion layer is formed on the outer peripheral surface of the silicon substrate and this diffusion layer is surrounded by an insulation layer. According to this arrangement, even when the potential of the electrolyte has been raised to a level which is positive with respect to the silicon substrate, an electrical isolation is established by the reverse dielectric strength exhibited by the P-N junction.
Inventors
- 👤 Tetsushi Sekiguchi
- 👤 Tetsuo Hamatani
- 👤 Hideo Ozawa
- 👤 Masao Takahashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 22:39
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/26; G01N27/403; G01N27/414
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
76 words
A field effect transistor for use as an ion sensor, comprising: a P-type silicon substrate having a top, a bottom and sides; a source region and a drain region of N-type material formed on said top of said P-type silicon substrate; an N-type isolation diffusion layer formed on the outer periphery of said bottom and sides of said P-type silicon substrate; and an insulating layer formed on the outer peripheral surface of said N-type isolation layer.
Claim 2
Dependent Claim
76 words
A field effect transistor for use as an ion sensor, comprising: a P-type silicon substrate having a top, a bottom and sides; a source region and a drain region of N-type material formed on said top of said P-type silicon substrate; an N-type isolation diffusion layer formed on the outer periphery of said bottom and sides of said P-type silicon substrate; and an insulating layer formed on the outer peripheral surface of said N-type isolation layer.
Claim 3
Dependent Claim
54 words
A field effect transistor for use as an ion sensor according to claim 1, wherein said insulating layer is a double layer composed of a silicon nitride film and a silicon oxide film, said silicon oxide film being adjacent said P-type silicon substrate, and said silicon nitride film being adjacent said silicon oxide film.
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) | 1993-02-19 | 1993-08-21 | 1994-02-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-02-19 | 1997-08-21 | 1998-02-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-02-19 | 2001-08-21 | 2002-02-20 | $7700.00 | Window Closed / Lapsed |