US4144636A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for manufacture of a moisture sensor
Assignee: International Business Machines Corp
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Filing: 1977-08-08
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Granted: 1979-03-20
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Expires: 1997-08-08
Abstract
Abstract A method and resulting structure for a relative humidity monitor which can be built into an integrated circuit chip. A small area on a silicon chip is made porous by anodic etching. This region is then oxidized and a metal counter electrode is deposited over part of the porous area. The surface area in the dielectric under the counter electrode is very high and because of the openness of the structure, ambient moisture can quickly diffuse into the dielectric under the electrode and adsorb onto the silicon dioxide surface. Changes in ambient humidity will then be reflected by measurable changes in capacitance or conductance of the device.
Inventors
- 👤 Paul J. Burkhardt
- 👤 Michael R. Poponiak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:32
CPC Classifications
H; H10; H10D; H10D48/00; H10D48/30; G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/12; G01N27/121; Y; Y10; Y10S; Y10S438/00; Y10S438/96
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
103 words
The method for producing a moisture sensor comprising: anodizing a region of a monocrystalline silicon body to form a porous silicon layer having an average porosity of 30 to 80 percent; oxidizing the surface of said porous silicon layer to form a porous silicon dioxide layer having an average porosity of 15 to 40 percent; and forming a plurality of spaced apart electrodes onto said sensor and wherein at least one of which is connected to the said porous silicon dioxide layer so as to allow the detection of electrical measurable changes due to adsorption of moisture in said porous silicon dioxide layer.
Claim 2
Independent Claim
103 words
The method for producing a moisture sensor comprising: anodizing a region of a monocrystalline silicon body to form a porous silicon layer having an average porosity of 30 to 80 percent; oxidizing the surface of said porous silicon layer to form a porous silicon dioxide layer having an average porosity of 15 to 40 percent; and forming a plurality of spaced apart electrodes onto said sensor and wherein at least one of which is connected to the said porous silicon dioxide layer so as to allow the detection of electrical measurable changes due to adsorption of moisture in said porous silicon dioxide layer.
Claim 3
Dependent Claim
30 words
The method of claim 1 wherein the porous silicon layer is formed in a 10 to 33 percent concentrated HF-water solution at from about 0.1 to 20 milliamps/cm 2 .
Claim 4
Dependent Claim
24 words
The method of claim 1 wherein the porous silicon dioxide layer is formed by thermal oxidation at a temperature greater than about 500° C.
Claim 5
Dependent Claim
15 words
The method of claim 1 wherein the porous silicon dioxide layer is formed by anodization.
Claim 6
Dependent Claim
32 words
The method of claim 1 wherein the porous silicon layer is formed in about 0.5 to 26 percent HF in HCl water solution at from about 0.1 to 20 milliamps/cm 2 .
Claim 7
Dependent Claim
21 words
The method of claim 1 wherein said electrodes include an electrode on said silicon body which allows measurable changes in capacitance.
Claim 8
Dependent Claim
30 words
The method of claim 1 wherein said electrodes include two spaced but interleaved serpentine patterns connected to said porous silicon dioxide layer so as to allow measurable changes in resistance.
Claim 9
Dependent Claim
16 words
The method of claim 1 wherein an integrated circuit is formed in said monocrystalline silicon body.
References Cited (Backward Citations)
US3835530A
Cited
US3919060A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-03-19 | 1982-09-18 | 1983-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-03-19 | 1986-09-18 | 1987-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-03-19 | 1990-09-18 | 1991-03-20 | $7700.00 | Window Closed / Lapsed |