GB2136451A - Depositing porous films by evaporating material on to a surface - Google Patents
Depositing porous films by evaporating material on to a surface Download PDFInfo
- Publication number
- GB2136451A GB2136451A GB08404775A GB8404775A GB2136451A GB 2136451 A GB2136451 A GB 2136451A GB 08404775 A GB08404775 A GB 08404775A GB 8404775 A GB8404775 A GB 8404775A GB 2136451 A GB2136451 A GB 2136451A
- Authority
- GB
- United Kingdom
- Prior art keywords
- mesh
- film
- porous
- deposited
- depositing
- 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
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
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/04—Coating on selected surface areas, e.g. using masks
- C23C14/042—Coating on selected surface areas, e.g. using masks using masks
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/02—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance
- G01N27/22—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating impedance by investigating capacitance
- G01N27/226—Construction of measuring vessels; Electrodes therefor
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- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physical Vapour Deposition (AREA)
Abstract
The material, e.g. gold, is evaporated onto the surface through a mesh. The film may be at least one of the water vapour porous electrodes provided on opposite faces of a slab of hygroscopic dielectric material to form a capacitor humidity sensor.
Description
SPECIFICATION
Method of depositing porous films
This invention relates to methods of depositing porous films.
In order for a deposited film of material to be porous it is necessary for the film to be thin. At the same time, the film will normally be required to be of sufficient thickness to constitute a substantially continuous film, for example, so as to provide an equipotential surface where, as is frequently the case, the film consists of electrically conductive material and constitutes an electrode of a device e.g a capacitor.
It is an object of the present invention to provide a method of depositing a porous film which facilitates the meeting of these two conflicting requirements.
According to the present invention a method of depositing a porous film of material onto a surface comprises evaporating the material onto the surface through a mesh.
The method has the advantage that a high degree of control may be exerted since the porosity can be controlled not only by controlling the quantity of deposited material, but also by choice of the mesh size and distance between the mesh and the surface.
One particular application of the invention is in the construction of humidity sensors of the kind comprising a capacitor comprising a slab of hygroscopic dielectric material provided with electrodes on its opposite faces at least one of which is porous to water vapour.
In such a device the porous electrode suitably consists of gold because of its chemical stability.
One method in accordance with the invention will now be described by way of example.
The method is used to form a porous gold electrode of a capacitor humidity sensor of the kind mentioned above.
The deposition is carried out in a conventional vacuum evaporator of the kind used widely in the manufacture of semi conductor and thin film circuits.
The gold to be deposited is placed in the furnace in a boat and the surface on which the gold is to be deposited is disposed horizontally, face down, about 1 2 centimetres above the boat.
The surface will normally be masked to restrict deposition to selected areas of the surface by a reticle plate or by a mask provided on the surface by known photolithographic techniques.
Between the boat and the surface, spaced 2 millimetres from the surface, there is disposed a stainless steel wire mesh of size 1 25 meshes to the centimetre, the mesh being held in a suitable frame.
Deposition of the film is effected by vapourising the gold by boiling, deposition of a satisfactory electrically conductive film, porous to water vapour, typically taking about half a minute.
The deposited film is found to be of smoothly
varying thickness with the maximum thickness at
points corresponding to the centres of the holes in
the mesh and minimum thickness along lines
corresponding to the centres of the wires of the
mesh. The porosity of the film is ensured by the
thinner areas, but at the same time the thinner
areas are of restricted area and connected by
relatively thick areas so that the film exhibits
overall good electrical conductivity.
It will be appreciated that the porosity and
electrical conductivity of the film may be
controlled by choice of the mesh size and spacing
of the mesh from the surface. Thus, in generai, the
difference in thickness of the thinner and thicker
areas may be increased by reducing the spacing or
increasing the mesh size. However for the best
results a mesh of size not less than 50 meshes to
the centimetre is used and the spacing between
the mesh and the surface is not more than 3
millimetres. It will be understood that the choice
of a suitable size for the area of the source of
material to be deposited will depend on the area
of the surface on which material is to be
deposited.However, it is pointed out that in
general the source should have a sufficiently large
area to avoid parts of the surface on which
material is to be deposited being totally screened
from the source by the wires of the mesh so that
virtually no material is deposited on such parts.
1. A method of depositing a porous film of
material onto a surface comprising evaporating
the material onto the surface through a mesh.
2. A method according to Claim 1 wherein said
surface is disposed substantially horizontally, face
down, above a source of said material, said mesh
being positioned between the surface and the
source substantially parallel to and adjacent said
surface.
3. A method according to Claim 1 or Claim 2
wherein said material is an electrically conductive
material.
4. A method according to Claim 3 wherein said
material is gold.
5. A method according to any one of the
preceding claims wherein said mesh is a metal
mesh.
6. A method according to Claim 5 wherein said
mesh is a stainless steel mesh.
7. A method according to any preceding claim wherein the mesh has not less than 50 meshes to the centimetre.
8. A method according to any preceding claim wherein the mesh is spaced from the surface by a distance not greater than 3 millimetres.
9. A method of depositing a porous film onto a surface substantially as hereinbefore described by way of example.
10. A porous film produced by a method according to any one of the preceding claims.
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (11)
1. A method of depositing a porous film of
material onto a surface comprising evaporating
the material onto the surface through a mesh.
2. A method according to Claim 1 wherein said
surface is disposed substantially horizontally, face
down, above a source of said material, said mesh
being positioned between the surface and the
source substantially parallel to and adjacent said
surface.
3. A method according to Claim 1 or Claim 2
wherein said material is an electrically conductive
material.
4. A method according to Claim 3 wherein said
material is gold.
5. A method according to any one of the
preceding claims wherein said mesh is a metal
mesh.
6. A method according to Claim 5 wherein said
mesh is a stainless steel mesh.
7. A method according to any preceding claim wherein the mesh has not less than 50 meshes to the centimetre.
8. A method according to any preceding claim wherein the mesh is spaced from the surface by a distance not greater than 3 millimetres.
9. A method of depositing a porous film onto a surface substantially as hereinbefore described by way of example.
10. A porous film produced by a method according to any one of the preceding claims.
11. A humidity sensor comprising a slab of hygroscopic dielectric material provided with electrodes on its opposite faces at least one of which comprises a porous film of material deposited by a method according to any one of
Claims 1 to 9.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB08404775A GB2136451B (en) | 1983-03-11 | 1984-02-23 | Depositing porous films by evaporating material on to a surface |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB838306718A GB8306718D0 (en) | 1983-03-11 | 1983-03-11 | Depositing porous films |
GB08404775A GB2136451B (en) | 1983-03-11 | 1984-02-23 | Depositing porous films by evaporating material on to a surface |
Publications (3)
Publication Number | Publication Date |
---|---|
GB8404775D0 GB8404775D0 (en) | 1984-03-28 |
GB2136451A true GB2136451A (en) | 1984-09-19 |
GB2136451B GB2136451B (en) | 1986-06-25 |
Family
ID=26285476
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB08404775A Expired GB2136451B (en) | 1983-03-11 | 1984-02-23 | Depositing porous films by evaporating material on to a surface |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2136451B (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0465973A1 (en) * | 1990-07-02 | 1992-01-15 | Xerox Corporation | Plywood effect suppression in photosensitive imaging members |
FR2750494A1 (en) * | 1996-07-01 | 1998-01-02 | S P S I Soc | High sensitivity capacitive humidity sensor |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1051251A (en) * | ||||
GB570200A (en) * | 1941-12-23 | 1945-06-27 | Cinema Television Ltd | Improvements in or relating to methods of coating surfaces by evaporation |
GB654708A (en) * | 1948-07-03 | 1951-06-27 | Emi Ltd | Improvements relating to the production of etched glass surfaces |
GB712105A (en) * | 1951-05-04 | 1954-07-21 | Nat Res Dev | Improvements in or relating to deposition of films and coatings |
GB1006076A (en) * | 1961-04-25 | 1965-09-29 | Emi Ltd | Improvements in or relating to methods of forming a pattern of conducting material ona substantially insulating support |
GB1418644A (en) * | 1971-12-03 | 1975-12-24 | Bosch Gmbh Robert | Metal coating |
-
1984
- 1984-02-23 GB GB08404775A patent/GB2136451B/en not_active Expired
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1051251A (en) * | ||||
GB570200A (en) * | 1941-12-23 | 1945-06-27 | Cinema Television Ltd | Improvements in or relating to methods of coating surfaces by evaporation |
GB654708A (en) * | 1948-07-03 | 1951-06-27 | Emi Ltd | Improvements relating to the production of etched glass surfaces |
GB712105A (en) * | 1951-05-04 | 1954-07-21 | Nat Res Dev | Improvements in or relating to deposition of films and coatings |
GB1006076A (en) * | 1961-04-25 | 1965-09-29 | Emi Ltd | Improvements in or relating to methods of forming a pattern of conducting material ona substantially insulating support |
GB1418644A (en) * | 1971-12-03 | 1975-12-24 | Bosch Gmbh Robert | Metal coating |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0465973A1 (en) * | 1990-07-02 | 1992-01-15 | Xerox Corporation | Plywood effect suppression in photosensitive imaging members |
FR2750494A1 (en) * | 1996-07-01 | 1998-01-02 | S P S I Soc | High sensitivity capacitive humidity sensor |
Also Published As
Publication number | Publication date |
---|---|
GB2136451B (en) | 1986-06-25 |
GB8404775D0 (en) | 1984-03-28 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PCNP | Patent ceased through non-payment of renewal fee |