Patent US4446474A successfully refreshed from Google Patents.
US4446474A
Expired / Lapsed
US
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Ion sensor FET with surface treated metal gate
Assignee: Olympus Corp
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Filing: 1980-06-27
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Granted: 1984-05-01
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Expires: 2000-06-27
Abstract
Abstract An ion sensor and more particularly ion sensitive field effect transistor comprising an inorganic film, and an impurity layer formed in at least surface layer of said inorganic film by thermal diffusion or ion implantation.
Inventors
- 👤 Takashi Mizusaki
- 👤 Tadayuki Matsuo
- 👤 Masayoshi Esashi
- 👤 Hiroshi Abe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 18:51
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/26; G01N27/403; G01N27/414
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
88 words
A field effect transistor type ion sensor comprising an inorganic film formed on a gate insulating film of a field effect transistor, and an impurity layer formed in at least the surface layer of said inorganic film, and containing an impurity sensitive to a given ion, said impurity layer being operative as an ion sensitive region when it makes contact with a test substance, and said inorganic film is formed of a composition selected from the group consisting of silver (Ag), copper (Cu), cadmium (Cd) and lead (Pb).
Claim 2
Dependent Claim
88 words
A field effect transistor type ion sensor comprising an inorganic film formed on a gate insulating film of a field effect transistor, and an impurity layer formed in at least the surface layer of said inorganic film, and containing an impurity sensitive to a given ion, said impurity layer being operative as an ion sensitive region when it makes contact with a test substance, and said inorganic film is formed of a composition selected from the group consisting of silver (Ag), copper (Cu), cadmium (Cd) and lead (Pb).
Claim 3
Dependent Claim
27 words
A field effect transistor type ion sensor according to claim 1, wherein said inorganic film is formed through a surface stabilizing film on said gate insulating film.
Claim 4
Dependent Claim
37 words
A field effect transistor type ion sensor according to claim 1, wherein one semiconductor substrate is provided with a plurality of gate portions and impurity layers sensitive to different ions are formed in said gate portions, respectively.
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) | 1987-05-01 | 1987-10-31 | 1988-05-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-05-01 | 1991-10-31 | 1992-05-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-05-01 | 1995-10-31 | 1996-05-01 | $7700.00 | Window Closed / Lapsed |