EP0137988A2
Expired / Lapsed
EP
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Infrared imager
Assignee: Raytheon Co
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Filing: 1984-08-24
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Granted: —
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Expires: 2004-08-24
Abstract
Abstract (@ An infrared imager, wherein a transparent gate (14) is separated from a very narrow bandgap semiconductor (106) (such as HgCdTe) by a thin dielectric (15, 62). The gate (14) is biased to create a depletion well in the semiconductor (106), and photo-generated carriers are collected in the well. The gate voltage is sensed to measure the accumulated charge. Preferably the accumulated charge is not sensed directly from the gate, but the gate output is repeatedly averaged with another capacitor, so that the output of the imager is sensed as an average over a number of read cycles, which provides a greatly improved signal-to-noise ratio. Preferably an array of the MIS detection devices is formed in a thin layer of HgCdTe (106), which is bonded to a silicon substrate (107) containing a corresponding array of the averaging capacitors with addressing and output connections, and via holes (16) through the HgCdTe are used to connect each detection device to its corresponding averaging capacitor.
Inventors
- 👤 Claude E. Tew
- 👤 Adam J. Lewis
- 👤 Eric F. Schulte
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 21:48
CPC Classifications
H; H10; H10W; H10W20/00; H10W20/01; H10W20/031; H10W20/069; H04; H04N; H04N23/00; H04N23/20; H10D; H10D62/00; H10D62/80; H10D62/86; H10D62/862; H10F; H10F39/00; H10F39/011; H10F39/022; H10F39/10; H10F39/12; H10F39/18; H10F39/184; H10F39/1843; H10F39/80; H10F39/811; H10P; H10P14/00; H10P14/60; H10P14/69; H10P14/692; H10P50/00; H10P50/20; H10P52/00; H10P95/00; H10P95/70
Claims Analysis
Total Claims: 49
Claim 1
Independent Claim
111 words
An infrared imager comprising: a plurality of detector locations, each said detector location comprising a substrate comprising a narrow-band-gap semiconductor, an insulator on said semiconductor, and a conductive storage gate on said insulator, said semiconductor being positioned to receive infrared photons; means, connected to said respective storage gates, for biasing said semiconductor at said respective detector locations into depletion, whereby optically generated carriers can collect in the depletion region defined beneath said respective storage gate; and means, connected to said storage gate, for detecting the potential of each said respective storage gate after said semiconductor beneath said storage gate has been exposed to infrared photons for a predetermined length of time.
Claim 2
Dependent Claim
111 words
An infrared imager comprising: a plurality of detector locations, each said detector location comprising a substrate comprising a narrow-band-gap semiconductor, an insulator on said semiconductor, and a conductive storage gate on said insulator, said semiconductor being positioned to receive infrared photons; means, connected to said respective storage gates, for biasing said semiconductor at said respective detector locations into depletion, whereby optically generated carriers can collect in the depletion region defined beneath said respective storage gate; and means, connected to said storage gate, for detecting the potential of each said respective storage gate after said semiconductor beneath said storage gate has been exposed to infrared photons for a predetermined length of time.
Claim 3
Dependent Claim
25 words
The imager of claim 1, wherein said semiconductor has a band gap which is less than that corresponding to the energy of a ten-micron-wavelength photon.
Claim 4
Dependent Claim
10 words
The imager of claim 2, wherein said semiconductor comprises HgCdTe.
Claim 5
Dependent Claim
12 words
The imager of claim 1, wherein said semiconductor comprises indium bismuth antimonide.
Claim 6
Dependent Claim
18 words
The imager of claim 1, further comprising means for recursively averaging the output potential of said storage gate.
Claim 7
Dependent Claim
14 words
The imager of claim 5, wherein said detector elements comprise HgCdTe glued onto silicon.
Claim 8
Dependent Claim
25 words
The imager of claim 6, wherein said means for biasing, said means for averaging, and said means for detecting are embodied in said silicon substrate.
Claim 9
Dependent Claim
40 words
The imager of claim 5, wherein said means for recursive averaging comprises a capacitor located in said silicon, said capacitor being repeatedly connected with said storage gate after said detector has been exposed to infrared light for an integration time.
Claim 10
Dependent Claim
20 words
The imager of claim 7, wherein said storage gate comprises a thin metal layer which is transparent to infrared radiation.
Claim 11
Dependent Claim
20 words
The imager of claim 6, wherein said storage gate is connected to said silicon through a via in said HgCdTe.
Claim 12
Dependent Claim
27 words
The imager of claim 1, wherein said semiconductor comprises HgCdTe, said insulator comprises zinc sulphide, and said storage gate comprises less than two hundred angstroms of nickel.
Claim 13
Dependent Claim
15 words
The imager of claim 1, wherein said detector locations are bump-bonded to a silicon substrate.
Claim 14
Dependent Claim
123 words
An infrared imager comprising: a plurality of detector locations, each said detector location comprising a substrate comprising a narrow-band-gap semiconductor, an insulator on said semiconductor, and a conductive storage gate on said insulator, said semiconductor being positioned to receive infrared photons; means, connected to said respective storage gates, for biasing said semiconductor at said respective detector locations into depletion, whereby optically generated carriers can collect in the depletion region defined beneath said respective storage gate; and means connected to said storage gate, for detecting the voltage of each said respective storage gate after said semiconductor beneath said storage gate has been exposed to infrared photons for a predetermined length of time; wherein said narrow-band-gap substrate is continuous across all of said detector locations.
Claim 15
Dependent Claim
123 words
An infrared imager comprising: a plurality of detector locations, each said detector location comprising a substrate comprising a narrow-band-gap semiconductor, an insulator on said semiconductor, and a conductive storage gate on said insulator, said semiconductor being positioned to receive infrared photons; means, connected to said respective storage gates, for biasing said semiconductor at said respective detector locations into depletion, whereby optically generated carriers can collect in the depletion region defined beneath said respective storage gate; and means connected to said storage gate, for detecting the voltage of each said respective storage gate after said semiconductor beneath said storage gate has been exposed to infrared photons for a predetermined length of time; wherein said narrow-band-gap substrate is continuous across all of said detector locations.
Claim 16
Dependent Claim
25 words
The imager of claim 13 wherein said semiconductor has a band gap which is less than that corresponding to the energy of a ten-micron-wavelength photon.
Claim 17
Dependent Claim
10 words
The imager of claim 14, wherein said semiconductor comprises HgCdTe.
Claim 18
Dependent Claim
18 words
The imager of claim 13, further comprising means for recursively averaging the output potential of said storage gate.
Claim 19
Dependent Claim
15 words
The imager of claim 16, wherein said HgCdTe substrate is glued onto a silicon substrate.
Claim 20
Dependent Claim
26 words
The imager of claim 17, wherein said means for biasing, said means for averaging, and said means for voltage detecting are embodied in said silicon substrate.
Claim 21
Dependent Claim
40 words
The imager of claim 16, wherein said means for recursive averaging comprises a capacitor located in said silicon, said capacitor being repeatedly connected with said storage gate after said detector has been exposed to infrared light for an integration time.
Claim 22
Dependent Claim
20 words
The imager of claim 18, wherein said storage gate comprises a thin metal layer which is transparent to infrared radiation.
Claim 23
Dependent Claim
20 words
The imager of claim 17, wherein said storage gate is connected to said silicon through a via in said HgCdTe.
Claim 24
Dependent Claim
37 words
The imager of claim 13, wherein said semiconductor comprises HgCdTe, said insulator comprises zinc sulfide, and said storage gate comprises less than two hundred angstroms of a metal selected from the group consisting of nickel and chromium.
Claim 25
Dependent Claim
107 words
An infrared imager comprising: an array of infrared detector locations, each said infrared detector comprising a narrow-bandgap semiconductor region, said narrow-bandgap semiconductor region being positioned to receive infrared photons, and means for providing an output signal indicative of infrared photon flux received by said narrow-bandgap semiconductor region; a silicon substrate, said silicon substrate being glued to said array of detector locations; said silicon substrate further comprising an array of averaging capacitors, said array of averaging capacitors being aligned with said array of detector locations; means for connecting each respective averaging capacitor to a corresponding detector location selectively; and means for reading out each of said averaging capacitors.
Claim 26
Dependent Claim
107 words
An infrared imager comprising: an array of infrared detector locations, each said infrared detector comprising a narrow-bandgap semiconductor region, said narrow-bandgap semiconductor region being positioned to receive infrared photons, and means for providing an output signal indicative of infrared photon flux received by said narrow-bandgap semiconductor region; a silicon substrate, said silicon substrate being glued to said array of detector locations; said silicon substrate further comprising an array of averaging capacitors, said array of averaging capacitors being aligned with said array of detector locations; means for connecting each respective averaging capacitor to a corresponding detector location selectively; and means for reading out each of said averaging capacitors.
Claim 27
Dependent Claim
24 words
The imager of claim 23, wherein said semiconductor has a bandgap which is less than that corresponding to the energy of a 10-micron-wavelength photon.
Claim 28
Dependent Claim
14 words
The imager of claim 23, wherein said semiconductor comprises Hg 1-X Cd X Te.
Claim 29
Dependent Claim
11 words
The imager of claim 23, wherein said semiconductor comprises indium antimonide.
Claim 30
Dependent Claim
13 words
The imager of claim 23, wherein each said detector location comprises a photodiode.
Claim 31
Dependent Claim
25 words
The imager of claim 23, wherein each said detector location is connected to said corresponding averaging capacitor through a via hole in said narrow-bandgap semiconductor.
Claim 32
Dependent Claim
23 words
The imager of claim 23, wherein said array of detector locations is bump-bonded to said array of averaging capacitors on said silicon substrate.
Claim 33
Dependent Claim
117 words
An infrared imager comprising: an array of infrared detector locations in a narrow-band- gap semiconductor substrate, said narrow-bandgap semiconductor substrate being positioned to receive infrared photons, each detector location comprising a diode having a barrier height less than 1/2 electron volt and means for providing an output signal indicative of infrared photon flux received by said semiconductor; a silicon substrate, said silicon substrate being glued to said array of detector locations; said silicon substrate further comprising an array of averaging capacitors, said array of averaging capacitors being aligned with said array of detector locations; means for connecting each respective averaging capacitor to a corresponding detector location selectively; and means for reading out each of said averaging capacitors.
Claim 34
Dependent Claim
117 words
An infrared imager comprising: an array of infrared detector locations in a narrow-band- gap semiconductor substrate, said narrow-bandgap semiconductor substrate being positioned to receive infrared photons, each detector location comprising a diode having a barrier height less than 1/2 electron volt and means for providing an output signal indicative of infrared photon flux received by said semiconductor; a silicon substrate, said silicon substrate being glued to said array of detector locations; said silicon substrate further comprising an array of averaging capacitors, said array of averaging capacitors being aligned with said array of detector locations; means for connecting each respective averaging capacitor to a corresponding detector location selectively; and means for reading out each of said averaging capacitors.
Claim 35
Dependent Claim
117 words
An infrared imager comprising: an array of infrared detector locations in a narrow-band- gap semiconductor substrate, said narrow-bandgap semiconductor substrate being positioned to receive infrared photons, each detector location comprising means for providing an output signal indicative of infrared photon flux received by said detector location, said narrow-bandgap semiconductor substrate extending continuously through all of said detector locations; a silicon substrate, said silicon substrate being glued to said narrow-bandgap semiconductor substrate; said silicon substrate further comprising an array of averaging capacitors, said array of averaging capacitors being aligned with said array of detector locations; means for connecting each respective averaging capacitor to a corresponding detector location selectively; and means for reading out each of said averaging capacitors.
Claim 36
Dependent Claim
117 words
An infrared imager comprising: an array of infrared detector locations in a narrow-band- gap semiconductor substrate, said narrow-bandgap semiconductor substrate being positioned to receive infrared photons, each detector location comprising means for providing an output signal indicative of infrared photon flux received by said detector location, said narrow-bandgap semiconductor substrate extending continuously through all of said detector locations; a silicon substrate, said silicon substrate being glued to said narrow-bandgap semiconductor substrate; said silicon substrate further comprising an array of averaging capacitors, said array of averaging capacitors being aligned with said array of detector locations; means for connecting each respective averaging capacitor to a corresponding detector location selectively; and means for reading out each of said averaging capacitors.
Claim 37
Dependent Claim
25 words
The imager of claim 31, wherein said narrow-bandgap semiconductor has a bandgap which is less than that corresponding to the energy of a 10-micron-wavelength photon.
Claim 38
Dependent Claim
15 words
The imager of claim 31, wherein said narrow-bandgap semiconductor comprises Hg 1-X Cd X Te.
Claim 39
Dependent Claim
12 words
The imager of claim 31, wherein said narrow-bandgap semiconductor comprises indium antimonide.
Claim 40
Dependent Claim
13 words
The imager of claim 31, wherein each said detector location comprises a photodiode.
Claim 41
Dependent Claim
26 words
The imager of claim 31, wherein each said detector location is connected to said corresponding averaging capacitor through a via hole in said narrow-bandgap semiconductor substrate.
Claim 42
Dependent Claim
23 words
The imager of claim 31, wherein said array of detector locations is bump-bonded to said array of averaging capacitors on said silicon substrate.
Claim 43
Independent Claim
51 words
A method for forming vias in HgCdTe, comprising the steps of: ion milling a hole through said HgCdTe, said hole being substantially smaller than the desired diameter of said via; and wet etching said HgCdTe, whereby said hole is enlarged to form a via having a desired size and smooth walls.
Claim 44
Independent Claim
51 words
A method for forming vias in HgCdTe, comprising the steps of: ion milling a hole through said HgCdTe, said hole being substantially smaller than the desired diameter of said via; and wet etching said HgCdTe, whereby said hole is enlarged to form a via having a desired size and smooth walls.
Claim 45
Dependent Claim
21 words
The method of claim 38, wherein said wet etching step comprises spraying said HgCdTe with a solution of bromine and methanol.
Claim 46
Dependent Claim
22 words
The method of claim 38, wherein said wet etching step applies a solution which comprises approximately 1/8% bromine in an organic solvent.
Claim 47
Dependent Claim
30 words
The method of claim 38, further comprising the preliminary step of applying a patterned masking material to expose only a predetermined portion of said HgCdTe to said ion milling step.
Claim 48
Dependent Claim
18 words
The method of claim 41, wherein said masking material is left in place during said wet etching step.
Claim 49
Dependent Claim
12 words
The method of claim 39, wherein said solvent consists essentially of methanol.
References Cited (Backward Citations)
US3977018A
Cited
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