GB2082562A - Coating germanium or silica with carbon - Google Patents
Coating germanium or silica with carbon Download PDFInfo
- Publication number
- GB2082562A GB2082562A GB8125094A GB8125094A GB2082562A GB 2082562 A GB2082562 A GB 2082562A GB 8125094 A GB8125094 A GB 8125094A GB 8125094 A GB8125094 A GB 8125094A GB 2082562 A GB2082562 A GB 2082562A
- Authority
- GB
- United Kingdom
- Prior art keywords
- carbon
- layer
- germanium
- glow discharge
- infra red
- 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
- 229910052732 germanium Inorganic materials 0.000 title claims abstract description 35
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 title claims abstract description 35
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 20
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 19
- 238000000576 coating method Methods 0.000 title claims description 8
- 239000011248 coating agent Substances 0.000 title claims description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title 2
- 239000000377 silicon dioxide Substances 0.000 title 1
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 16
- 239000010703 silicon Substances 0.000 claims abstract description 16
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims abstract description 13
- 239000007789 gas Substances 0.000 claims abstract description 12
- 229910052786 argon Inorganic materials 0.000 claims abstract description 8
- 238000000151 deposition Methods 0.000 claims abstract description 6
- 239000004215 Carbon black (E152) Substances 0.000 claims abstract description 5
- 229930195733 hydrocarbon Natural products 0.000 claims abstract description 5
- 150000002430 hydrocarbons Chemical class 0.000 claims abstract description 5
- 229910000078 germane Inorganic materials 0.000 claims abstract description 4
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 claims abstract description 3
- 238000010849 ion bombardment Methods 0.000 claims abstract description 3
- 229910000077 silane Inorganic materials 0.000 claims abstract description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 14
- 229910021385 hard carbon Inorganic materials 0.000 claims description 9
- 230000008021 deposition Effects 0.000 claims description 4
- 239000000758 substrate Substances 0.000 claims description 2
- 238000000034 method Methods 0.000 claims 9
- -1 carbon ions Chemical class 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 2
- 239000001273 butane Substances 0.000 description 2
- 229910003460 diamond Inorganic materials 0.000 description 2
- 239000010432 diamond Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 2
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 2
- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 1
- 239000005030 aluminium foil Substances 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 125000002534 ethynyl group Chemical group [H]C#C* 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
- C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
- C23C16/503—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using dc or ac discharges
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/26—Deposition of carbon only
-
- G02B1/105—
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
- G02B1/14—Protective coatings, e.g. hard coatings
-
- 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
- H01L31/02—Details
- H01L31/0216—Coatings
- H01L31/02161—Coatings for devices characterised by at least one potential jump barrier or surface barrier
Abstract
An infrared transparent element (8) of germanium or silicon is coated with a layer of hard infrared transparent carbon. The carbon is deposited on the element, used as a cathode (7, 8) in a glow discharge chamber (1) by applying a D.C. voltage (12) to a hydrocarbon gas at a pressure of e.g. 10<-1> to 10<-2> Torr. Prior to depositing the carbon the element may be heated and cleaned using argon ion bombardment. Layers of germanium and silicon may also be deposited using the gases germane and silane respectively. <IMAGE>
Description
SPECIFICATION
Coating infra red transparent semiconductor material
This invention relates to the coating of infra red transparent semi-conductor materials e.g. germanium and silicon.
The materials germanium and silicon can be produced in infra red (IR) transparent optical quality and are thus useful in lenses and windows for thermal imager systems. Such systems are used for night time viewing e.g. as part of burglar alarms, or for externally detecting high temperature areas in buildings to assist in applying insulation.
One problem with germanium and silicon is their high refractive indices - hence the need for antireflection coatings. There are various single and multiple anti-reflection coatings for germanium, some of which are able to provide abrasion and chemically durable layers.
It has been reported, "Thin Solid Films" 58 (1979) 107, L. Holland and S. M. Ojha, that infra red transparent thin hard carbon layers may be deposited on germanium by use of an r.f. glow discharge system.
In the same paper reference is also made to D.C.
glow discharge being used to deposit a hard carbon film on a metal cathode. It appears to have been believed that growth of hard carbon in a D.C. glow discharge system would not be possible on germanium due to charging of the surface.
It has now been found that hard carbon layers can be deposited onto a germanium cathode using the straightforward D.C. glow discharge without the need to compensate for surface charge.
According to this invention a germanium or silicon element is coated with a thin layer of hard carbon grown in a D.C. glow discharge chamber.
The germanium or silicon element is shaped in the form of a flat or curved plate, or a lens.
The hard carbon layer is deposited in a chamber which is evacuated, then filled with a hydro carbon gas. A D.C. voltage is applied to a holder carrying the germanium or silicon element and a glow discharge is established. This forms a plasma from which carbon ions strike the germanium or silicon and form a hard diamond like layer that is vary hard (diamondlike) and transparent in the 3 to 5 and 8 to 14 ,am wavelength regions of the electro magnetic spectrum.
Prior to depositing the carbon the germanium or silicon may be cleaned by argon ions. This also provides a heating of the semiconductor to assist in good bonding of the carbon. Additionally the germanium or silicon may be heated by a heater in the holder.
The invention will now be described, by way of example only, with reference to the accompanying drawing which shows apparatus for coating germanium.
As shown in the drawing a chamber 1 has a gas inlet port 2, and an outlet port 3 connected to a vacuum pump 4. Valves 5, 6 control flow through these ports 2, 3. Inside the chamber 1 is a holder 7 which carries a piece of germanium 8, a flat plate or lens. The holder7 may contain a heater9 and/or cooler and is electrically insulated from the chamber 1. Electrical leads 10, 11 pass from the holder7 to a
D.C. power supply 12 and heater/cooler supply 13 outside the chamber 1.
The germanium plate or lens 8 is an optical quality material transparent in the 3-5 and 8-14 ,am wavelength, its electrical resistivity is around 5-20 ohm cm.
Operation to coat the germanium 8 is as follows.
The chamber 1 is evacuated to about 10-4 Torr. or lowerto remove air and contaminants. Argon gas is bled into the chamber 1 whilst the pump 6 is throttled down to give a pressure of about 101 to 102 Torr.
A AD.C. voltage of about -2 to -5 kV is applied to the germanium 8 and holder 7 causing initiation of a glow discharge. Argon ions from the plasma thus created strike the germanium 8 to both clean its surface and raise its temperature. Typically 10 minutes of argon ion bombardment is used.
Whilst maintaining the glow discharge, the argon supply is stopped and a hydrocarbon gas emitted into the chamber 1. This gas may be butane, methane, acetylene, etc. and forms hydro-carbon plasma. A layer of hard diamond like carbon is formed by positively charged carbon ions being attracted to and striking the negatively charged germanium 8 where they gradually build up a layer of the required thickness. Typically a 1 ,am thick layer is formed in about 1 hour.
To provide an anti-reflection layer the optical thickness of the carbon is about one quarter wavelength at the required operating wavelength e.g. 1.2 ,am thickness in the 8-13 ,am wavelength band.
When the layer is fully grown the D.C. supply is stopped, the vacuum inside the chamber is released, and the germanium plate or lens removed.
In a modification the argon ion heating step may be omitted. Heating of germanium to e.g. 2500C may be by the heater 9 in the holder 7. Above about 3000C the carbon deposit becomes graphite and absorbing to infra red.
The negative potential applied to the germanium substrate may be increased as a carbon layer builds up, to overcome the insulating effect of the carbon layer which tends to limit the layer thickness.
To prevent deposition of carbon where not wanted e.g. on side and lower surface of the germanium, such areas may be covered with aluminium foil prior to placing the germanium element in the chamber.
Additionally electrode screening 14 may be used to prevent deposition on the cathode structure.
Silicon is coated in a manner similarto that for germanium.
Multilayers of anti-reflection coatings may be formed by the apparatus shown in the drawings. For example silicon and germanium layers may be grown in a DC glow discharge using the gas silane and germane.
Thus for example alternate layers of carbon and germanium may be grown on a germanium lens using butane and germane gas supplies. The final layer is preferably carbon because of its abrasion resistance.
Claims (9)
1. A method of coating an infra red transparent germanium or silicon element with a layer of hard carbon wherein the element is placed on a cathode structure in a glow discharge chamber containing a hydrocarbon gas at a pressure below atmospheric pressure characterised by the application of a D.C.
voltage to the cathode whereby a glow discharge is initiated and maintained in the chamber so that a layer of hard substantially infra red transparent carbon is grown on the element.
2. The method of claim 1 wherein priorto deposition of the carbon the element is subjected to argon ion bombardment in a glow discharge.
3. The method of claim 1 wherein the element is heated before deposition of the carbon layer.
4. The method of claim 1 wherein the temperature of the substrate is kept below 300 C during growth of the carbon layer.
5. The method of claim 1 wherein a layer of silicon is also deposited by glow discharge from the gas silane.
6. The method of claim 1 wherein a layer of ger- manium is also deposited by glow discharge from the gas germane.
7. A shaped element of infra red transparent germanium coated with a layer of substantially infra red transparent hard carbon by the method of claim 1.
8. A shaped element of infra red transparent silicon coated with a layer of substantially infra red transparent hard carbon by the method of claim 1.
9. The method of claim 1 substantially as hereinbefore described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8125094A GB2082562B (en) | 1980-08-21 | 1981-08-17 | Coating germanium of silicon with carbon |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8027279 | 1980-08-21 | ||
| GB8125094A GB2082562B (en) | 1980-08-21 | 1981-08-17 | Coating germanium of silicon with carbon |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2082562A true GB2082562A (en) | 1982-03-10 |
| GB2082562B GB2082562B (en) | 1983-12-14 |
Family
ID=26276651
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8125094A Expired GB2082562B (en) | 1980-08-21 | 1981-08-17 | Coating germanium of silicon with carbon |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2082562B (en) |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3237851A1 (en) * | 1981-10-21 | 1983-04-28 | RCA Corp., 10020 New York, N.Y. | Amorphous, carbon-containing film and process for the preparation thereof |
| EP0106638A1 (en) * | 1982-10-12 | 1984-04-25 | National Research Development Corporation | Method and apparatus for growing material in a glow discharge |
| EP0106637A1 (en) * | 1982-10-12 | 1984-04-25 | National Research Development Corporation | Infra red transparent optical components |
| US4504519A (en) * | 1981-10-21 | 1985-03-12 | Rca Corporation | Diamond-like film and process for producing same |
| GB2165266A (en) * | 1982-10-12 | 1986-04-09 | Nat Res Dev | Infra red transparent optical components |
| US4704339A (en) * | 1982-10-12 | 1987-11-03 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | Infra-red transparent optical components |
| WO1988010321A1 (en) * | 1987-06-25 | 1988-12-29 | University Of Houston-University Park | Process for the deposition of diamond films |
| EP0463812A2 (en) * | 1990-06-27 | 1992-01-02 | Texas Instruments Incorporated | Infrared transmissive protective window |
| GB2280201A (en) * | 1987-06-15 | 1995-01-25 | Secr Defence | Infra red transparent window |
| EP0798572A1 (en) * | 1996-02-13 | 1997-10-01 | Gec Marconi Ltd. | Coatings |
| US5723207A (en) * | 1988-01-21 | 1998-03-03 | The National Research Development Corporation | Infra-red transparant materials |
-
1981
- 1981-08-17 GB GB8125094A patent/GB2082562B/en not_active Expired
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4504519A (en) * | 1981-10-21 | 1985-03-12 | Rca Corporation | Diamond-like film and process for producing same |
| DE3237851A1 (en) * | 1981-10-21 | 1983-04-28 | RCA Corp., 10020 New York, N.Y. | Amorphous, carbon-containing film and process for the preparation thereof |
| US4704339A (en) * | 1982-10-12 | 1987-11-03 | The Secretary Of State For Defence In Her Britannic Majesty's Government Of The United Kingdom Of Great Britain And Northern Ireland | Infra-red transparent optical components |
| GB2129833A (en) * | 1982-10-12 | 1984-05-23 | Secr Defence | Method and apparatus for depositing coatings in a glow discharge |
| EP0106637A1 (en) * | 1982-10-12 | 1984-04-25 | National Research Development Corporation | Infra red transparent optical components |
| GB2165266A (en) * | 1982-10-12 | 1986-04-09 | Nat Res Dev | Infra red transparent optical components |
| EP0106638A1 (en) * | 1982-10-12 | 1984-04-25 | National Research Development Corporation | Method and apparatus for growing material in a glow discharge |
| GB2280201A (en) * | 1987-06-15 | 1995-01-25 | Secr Defence | Infra red transparent window |
| GB2280201B (en) * | 1987-06-15 | 1995-06-28 | Secr Defence | Infra red transparent windows |
| WO1988010321A1 (en) * | 1987-06-25 | 1988-12-29 | University Of Houston-University Park | Process for the deposition of diamond films |
| US5723207A (en) * | 1988-01-21 | 1998-03-03 | The National Research Development Corporation | Infra-red transparant materials |
| EP0463812A2 (en) * | 1990-06-27 | 1992-01-02 | Texas Instruments Incorporated | Infrared transmissive protective window |
| EP0463812A3 (en) * | 1990-06-27 | 1992-09-16 | Texas Instruments Incorporated | Infrared transmissive protective window |
| EP0798572A1 (en) * | 1996-02-13 | 1997-10-01 | Gec Marconi Ltd. | Coatings |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2082562B (en) | 1983-12-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PE20 | Patent expired after termination of 20 years |
Effective date: 20010816 |