US5451786A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Uncooled mis capacitor for infrared detection
Assignee: Raytheon Co
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Filing: 1994-04-19
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Granted: 1995-09-19
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Expires: 2014-04-19
Abstract
Abstract An uncooled thermal detector (10) includes a MIS capacitor (12) that is suspended from a material (26, 26a) having a low thermal conductivity. The MIS capacitor includes a doped semiconductor body portion (14) having a gate dielectric (20), a gate electrode (22), and a second electrode (24) disposed over a surface thereof. In operation, the capacitance of the MIS capacitor at a frequency near a high-frequency/low-frequency transition is measured or sensed. As the temperature of the MIS capacitor increases, the sensed capacitance increases because minority carriers are able to respond faster to a modulating gate voltage. Similarly, if the temperature decreases, the sensed capacitance decreases, because the minority carriers respond more slowly. A high thermal coefficient of capacitance (> 20%/K) is achieved at all gate bias values for which the MIS capacitor is in inversion. By a suitable choice of doping level and the introduction of a deep level (24) to control the minority-carrier lifetime, the transition frequency may be tailored to a desired operating frequency at a given temperature. A method for fabricating the uncooled detector, and an array of same, within a Si film (2) of an SOI wafer (1) is also disclosed.
Inventors
- 👤 Kenneth Kosai
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:19
CPC Classifications
G; G01; G01J; G01J5/00; G01J5/10; G01J5/34
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
80 words
A method of operating a thermal detector, comprising the steps of: providing a metal-insulator-semiconductor MIS capacitor having an associated temperature dependent transition frequency between low-frequency C-V operation and high-frequency C-V operation; applying an electrical signal to said MIS capacitor, said electrical signal having a characteristic that is a function of the transition frequency; and responsive to the applied electrical signal, sensing a capacitance of the MIS capacitor, the sensed capacitance being a function of the temperature of the MIS capacitor.
Claim 2
Independent Claim
80 words
A method of operating a thermal detector, comprising the steps of: providing a metal-insulator-semiconductor MIS capacitor having an associated temperature dependent transition frequency between low-frequency C-V operation and high-frequency C-V operation; applying an electrical signal to said MIS capacitor, said electrical signal having a characteristic that is a function of the transition frequency; and responsive to the applied electrical signal, sensing a capacitance of the MIS capacitor, the sensed capacitance being a function of the temperature of the MIS capacitor.
Claim 3
Dependent Claim
18 words
A method as set forth in claim 1 wherein the characteristic is a frequency of the electrical signal.
Claim 4
Dependent Claim
22 words
A method as set forth in claim 2 wherein the frequency of the electrical signal is approximately equal to the transition frequency.
Claim 5
Dependent Claim
19 words
A method as set forth in claim 1 wherein the characteristic is a pulse width of the electrical signal.
Claim 6
Dependent Claim
30 words
A method as set forth in claim 4 wherein the pulse width of the electrical signal is approximately equal to 1/2τf T , where f T is the transition frequency.
Claim 7
Dependent Claim
35 words
A method as set forth in claim 1 and further comprising the step of: adjusting the characteristic of the applied electrical signal to compensate for a change in an ambient temperature of the MIS capacitor.
Claim 8
Dependent Claim
85 words
A method as set forth in claim 1 wherein the step of providing includes an initial step of adjusting the transition frequency to a desired value by the steps of: selecting a doping concentration for a semiconductor body portion of the MIS capacitor, the doping concentration being selected to provide a desired concentration of minority charge carriers within the semiconductor body portion; and providing a deep trap for the semiconductor body portion to control a lifetime of minority charge carriers within the semiconductor body portion.
Claim 9
Dependent Claim
27 words
A method as set forth in claim 1, wherein the step of applying includes an initial step of forming a depletion region within the semiconductor body portion.
Claim 10
Dependent Claim
88 words
A thermal detection system, comprising: at least one metal-insulator-semiconductor MIS capacitor having an associated temperature dependent transition frequency between low-frequency C-V operation and high-frequency C-V operation; means for applying an electrical signal to said at least one MIS capacitor, said electrical signal having a characteristic that is a function of the transition frequency; and means, responsive to the applied electrical signal, for sensing a capacitance of the at least one MIS capacitor, the sensed capacitance being a function of the temperature of the at least one MIS capacitor.
Claim 11
Dependent Claim
88 words
A thermal detection system, comprising: at least one metal-insulator-semiconductor MIS capacitor having an associated temperature dependent transition frequency between low-frequency C-V operation and high-frequency C-V operation; means for applying an electrical signal to said at least one MIS capacitor, said electrical signal having a characteristic that is a function of the transition frequency; and means, responsive to the applied electrical signal, for sensing a capacitance of the at least one MIS capacitor, the sensed capacitance being a function of the temperature of the at least one MIS capacitor.
Claim 12
Dependent Claim
18 words
A system as set forth in claim 9 wherein the characteristic is a frequency of the electrical signal.
Claim 13
Dependent Claim
22 words
A system as set forth in claim 10 wherein the frequency of the electrical signal is approximately equal to the transition frequency.
Claim 14
Dependent Claim
19 words
A system as set forth in claim 9 wherein the characteristic is a pulse width of the electrical signal.
Claim 15
Dependent Claim
30 words
A method as set forth in claim 12 wherein the pulse width of the electrical signal is approximately equal to 1/2τf T , where f T is the transition frequency.
Claim 16
Dependent Claim
58 words
A system as set forth in claim 9 wherein said MIS capacitor includes a semiconductor body portion having a doping concentration selected to provide a desired concentration of minority charge carriers within the semiconductor body portion, said semiconductor body portion further including a deep trap for controlling a lifetime of minority charge carriers within the semiconductor body portion.
Claim 17
Dependent Claim
47 words
A system as set forth in claim 9, and further comprising: means for sensing an ambient temperature of said MIS capacitor; and means, responsive to said temperature sensing means, for adjusting the characteristic of the applied electrical signal to compensate for a change in the ambient temperature.
References Cited (Backward Citations)
US3562425A
Cited
US3497698A
Cited
FR2017497A1
Cited
US3786441A
Cited
US4210922A
Cited
US4197469A
Cited
JPS57206838A
Cited
US4603258A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1998-09-18 | 1999-03-20 | 1999-09-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-09-18 | 2003-03-20 | 2003-09-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-09-18 | 2007-03-20 | 2007-09-19 | $7700.00 | Window Closed / Lapsed |