GB2197984A - Cadmium mercury telluride photodiode - Google Patents
Cadmium mercury telluride photodiode Download PDFInfo
- Publication number
- GB2197984A GB2197984A GB08723068A GB8723068A GB2197984A GB 2197984 A GB2197984 A GB 2197984A GB 08723068 A GB08723068 A GB 08723068A GB 8723068 A GB8723068 A GB 8723068A GB 2197984 A GB2197984 A GB 2197984A
- Authority
- GB
- United Kingdom
- Prior art keywords
- type
- substrate
- infra
- layer
- heterojunction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 229910000661 Mercury cadmium telluride Inorganic materials 0.000 title claims description 14
- MCMSPRNYOJJPIZ-UHFFFAOYSA-N cadmium;mercury;tellurium Chemical compound [Cd]=[Te]=[Hg] MCMSPRNYOJJPIZ-UHFFFAOYSA-N 0.000 title claims description 14
- 239000000758 substrate Substances 0.000 claims abstract description 19
- 229910052751 metal Inorganic materials 0.000 claims abstract description 6
- 239000002184 metal Substances 0.000 claims abstract description 6
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 6
- 239000010703 silicon Substances 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims description 12
- 230000003628 erosive effect Effects 0.000 claims description 5
- MARUHZGHZWCEQU-UHFFFAOYSA-N 5-phenyl-2h-tetrazole Chemical compound C1=CC=CC=C1C1=NNN=N1 MARUHZGHZWCEQU-UHFFFAOYSA-N 0.000 claims description 3
- 230000003667 anti-reflective effect Effects 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 claims 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 5
- 238000000992 sputter etching Methods 0.000 abstract 1
- 150000002500 ions Chemical class 0.000 description 4
- 239000000463 material Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
- 238000010849 ion bombardment Methods 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000004943 liquid phase epitaxy Methods 0.000 description 1
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000001451 molecular beam epitaxy Methods 0.000 description 1
- 229920002120 photoresistant polymer Polymers 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 229910052724 xenon Inorganic materials 0.000 description 1
- -1 xenon ions Chemical class 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
- H01L31/0256—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by the material
- H01L31/0264—Inorganic materials
- H01L31/0296—Inorganic materials including, apart from doping material or other impurities, only AIIBVI compounds, e.g. CdS, ZnS, HgCdTe
- H01L31/02966—Inorganic materials including, apart from doping material or other impurities, only AIIBVI compounds, e.g. CdS, ZnS, HgCdTe including ternary compounds, e.g. HgCdTe
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/08—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors
- H01L31/10—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof in which radiation controls flow of current through the device, e.g. photoresistors characterised by potential barriers, e.g. phototransistors
- H01L31/101—Devices sensitive to infrared, visible or ultraviolet radiation
- H01L31/102—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier
- H01L31/109—Devices sensitive to infrared, visible or ultraviolet radiation characterised by only one potential barrier the potential barrier being of the PN heterojunction type
Landscapes
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Electromagnetism (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Light Receiving Elements (AREA)
Abstract
A CMT photodiode is formed by bonding to a silicon chip (2) an epitaxially grown CMT pn-junction (1). A hole (8) is formed through the junction layers (9, 10) by ion-etching, which converts the p-type region of the inner surface of the hole to n-type, and exposes a metal contact pad (6) on the silicon substrate. A homojunction is thus formed in parallel with the heterojunction. The invention enables the use of high quality grown junctions in CMT photodetectors. <IMAGE>
Description
Cadmium Mercury Telluride Photodiode
This invention relates to a method of forming a cadmium mercury telluride (CMT) infra-red detector.
It is known to use a pn junction made of cadmium mercury telluride and mounted on a suitable substrate to form a photodiode.
Standard methods of producing the pn junction are by diffusion, ion implantation or ion bombardment of a body of p-type CMT to convert a layer of the body to n-type. However, owing to the greater number of crystalline defects, the quality of junctions produced by these damage techniques is poor compared with an epitaxially grown CMT junction. There is a requirement for a reliable interconnect scheme for a high quality grown pn junction; this invention provides an alternative to the known 'Indium Bump' and 'flip-chip' bonding techniques.
An object of this invention is to provide a method of forming a CMT photodetector using a grown heterojunction.
According to the invention a method of forming an infra-red detector using a grown cadmium mercury telluride heterojunction diode includes the steps of attaching to a substrate the p-type face of the heterojunction diode which comprises a p-type layer and an n-type
layer, the p-type layer having a mole fraction of cadmium telluride
greater than that of the n-type layer, forming a hole by ion erosion through both layers of the heterojunction diode to expose part of a contact pad on the substrate, the region of the p-type layer exposed by the ion erosion being converted to n-type, and lining the hole with contact metal, thereby forming a homojunction in parallel with the heterojuncti on.
Preferably the p-type face of the heterojunction diode to be attached to the substrate is covered by a passivating layer. The heterojunction diode may also incorporate an anti reflection layer.
The substrate is suitably silicon.
The photodetector may be one of an array of mutually isolated photodetectors formed on the substrate.
The invention also includes a photodetector made by any method as aforesaid.
One embodiment of the invention will now be described, by way of example, with reference to the accompanying - drawings, of which:
Figure 1 shows a section through a segment of a CMT heterojunction on a substrate and
Figure 2 shows a section through one of an array of CMT detector elements in accordance with the invention.
Referring to Figure 1, a pn junction layer 1 of CMT is bonded to a substrate 2 by a bonding layer 4. A metal contact pad 6 is provided set into the bonding surface of the substrate.
The heterojunction 1 is grown by metal organic chemical vapour deposition to suit the particular requirements of the detector.
The lower layer 9 of the heterojunction, adjacent the substrate, is p-type, the upper layer 10 is n-type. The mole fraction of cadmium telluride in the p-type layer 9 is greater than that in the n-type layer 10. The junction could also be grown by molecular beam epitaxy or 2-stage liquid phase epitaxy.
Before being bonded to the substrate the p-type face of the heterojunction 1 is provided with a passivating layer 12 to prevent degradation of the semiconductor material. Using a very thin layer of epoxy resin as adhesive, the junction layer is bonded to the substrate 2, which is a silicon chip. To complete the device a homojunction is required in parallel with this pn heterojunction.
The surface of the n-type layer 10 is masked with photoresist and the semiconductor material is ion etched right through to the contact pad 6 by conventional ion erosion techniques using, for example, argon or xenon ions. As shown in Figure 2, the metal contact pad 6 thus forms the base of a hole 8 cut through the junction layer 1. The region of the layer 9 forming the wall of the hole 8, where it was originally p-type, is converted to n-type by the ion beam so that there is a continuous layer of n-type CMT running from the upper surface of the detector, i.e. the exposed face of layer 10, to the contact pad 6. Contact metal is then deposited over the wall and base of the hole. A homojunction is thus formed in the layer 9 between the p-type and converted n-type material in parallel with the heterojunction. The compositions are selected so that the heterojunction determines the infrared response and noise characteristcs and the homojunction acts as a noiseless isolation device.
Figures 1 and 2 show a segment containing one detector element of an array of such elements. A large number of contact pads are deposited on the silicon multiplexer chip 2 each of which forms the base of a respective hole 8. The individual detector elements are isolated by, for example, chemically etching the n-type surface to form isolating regions. This can be carried out before or after the junction layer 1 is bonded to the substrate 2.
The finished detector may incorporate an anti-reflection coating.
Claims (8)
1. A method of forming an infra-red detector using a grown cadmium mercury telluride heterojunction diode comprising the steps of attaching to a substrate the p-type face of said heterojunction diode which comprises a p-type layer and an n-type layer, the p-type layer having a mole fraction of cadmium telluride greater than that of the n-type layer, forming a hole by ion erosion through both layers of the heterojunction diode to expose part of a contact pad on the substrate, the region of the p-type layer exposed by the ion erosion being converted to n-type, and lining said hole with contact metal, thereby forming a homojunction in parallel with said heterojunction.
2. A method according to Claim 1 including the step of passivating said p-type face before attaching it to said substrate.
3. A method according to Claim 1 or 2 including the step of providing an anti reflective layer.
4. A method according to any of Claims 1 to 3 wherein said substrate is silicon.
5. An infra-red detector made according to the method claimed in any preceding claim.
6. An infra-red detector array comprising a plurality of detectors as claimed in Claim 5 formed on a single substrate and electrically isolated from each other.
7. An infra-red detector substantially as hereinbefore described with reference to the accompanying drawings.
8. A method of making an infra-red detector substantially as hereinbefore described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB868627886A GB8627886D0 (en) | 1986-11-21 | 1986-11-21 | Cadmium mercury telluride photodiode |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8723068D0 GB8723068D0 (en) | 1987-11-25 |
| GB2197984A true GB2197984A (en) | 1988-06-02 |
| GB2197984B GB2197984B (en) | 1991-02-20 |
Family
ID=10607722
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB868627886A Pending GB8627886D0 (en) | 1986-11-21 | 1986-11-21 | Cadmium mercury telluride photodiode |
| GB8723068A Expired - Lifetime GB2197984B (en) | 1986-11-21 | 1987-10-01 | Cadmium mercury telluride photodiode |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB868627886A Pending GB8627886D0 (en) | 1986-11-21 | 1986-11-21 | Cadmium mercury telluride photodiode |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB8627886D0 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5185648A (en) * | 1990-09-12 | 1993-02-09 | U.S. Philips Corp. | Plural-wavelength infrared detector devices |
| US5198370A (en) * | 1991-04-17 | 1993-03-30 | Mitsubishi Denki Kabushiki Kaisha | Method for producing an infrared detector |
| RU2611211C1 (en) * | 2015-11-20 | 2017-02-21 | Акционерное общество "НПО "Орион" | Method of passivating surface of cadmium-mercury telluride |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1259212A (en) * | 1968-07-01 | 1972-01-05 | ||
| US4295002A (en) * | 1980-06-23 | 1981-10-13 | International Business Machines Corporation | Heterojunction V-groove multijunction solar cell |
-
1986
- 1986-11-21 GB GB868627886A patent/GB8627886D0/en active Pending
-
1987
- 1987-10-01 GB GB8723068A patent/GB2197984B/en not_active Expired - Lifetime
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1259212A (en) * | 1968-07-01 | 1972-01-05 | ||
| US4295002A (en) * | 1980-06-23 | 1981-10-13 | International Business Machines Corporation | Heterojunction V-groove multijunction solar cell |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5185648A (en) * | 1990-09-12 | 1993-02-09 | U.S. Philips Corp. | Plural-wavelength infrared detector devices |
| US5198370A (en) * | 1991-04-17 | 1993-03-30 | Mitsubishi Denki Kabushiki Kaisha | Method for producing an infrared detector |
| RU2611211C1 (en) * | 2015-11-20 | 2017-02-21 | Акционерное общество "НПО "Орион" | Method of passivating surface of cadmium-mercury telluride |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8723068D0 (en) | 1987-11-25 |
| GB8627886D0 (en) | 1987-04-15 |
| GB2197984B (en) | 1991-02-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |