Coating insulating materials by glow discharge
AssigneeNational Research Development Corporation
InventorsGeoffrey W. Green, Alan H. Lettington
Life of this patent
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Abstract
Coatings of hard carbon, silicon, or germanium are applied to electrically insulating materials in a D.C. glow discharge chamber. Initiation and maintenance of a glow discharge is ensured by using a cathode of larger area than the material to be coated. For example the cathode may be twice the diameter of the material to be coated. Materials capable of being coated include zinc sulphide, zinc selenide, silica, and glass. The gases used are hydrocarbon e.g. butane, methane, etc. for carbon coatings; silane for silicon coatings; and germane for germanium coatings.
Claims25
A method of depositing coatings on an electrically insulating material substrate in a glow discharge chamber supplied with D.C. electrical power wherein the substrate is mounted on an electrically conducting cathode of larger area than the substrate whereby the exposed area of the cathode serves to maintain a glow discharge and dark space above the substrate.
An apparatus for depositing a coating on an electrically insulating substrate, comprising:
- a vacuum chamber;
- an anode structure within said vacuum chamber;
- means for providing a vacuum condition in said chamber;
- means for supplying a gas into said chamber;
- a cathode structure, within said chamber, having a recessed surface for carrying said substrate to be coated, said cathode structure having a substantially larger area than said substrate so that exposed areas of said cathode structure maintain a glow discharge and a dark space above said substrate while D.C. power is applied to said anode and cathode structures;
- and
- means for supplying D.C. power to said anode and cathode structures.
An apparatus for depositing a coating on an electrically insulating substrate, comprising:
- a vacuum chamber;
- an anode structure within said vacuum chamber;
- means for providing a vacuum condition in said chamber;
- means for supplying a gas into said chamber;
- a cathode structure, within said chamber, for carrying said substrate to be coated, the cathode structure having a substantially larger area than that of said substrate so that exposed areas of said cathode structure maintain a glow discharge and a dark space above said substrate while D.C. power is applied to said anode and cathode structures;
- a grounded shield surrounding said cathode structure for confining the glow discharge;
- and
- means for supplying D.C. power to said anode and cathode structures.
A substrate having a surface coated with a first thin bonding layer of silicon and a second layer of infra red transparent hard carbon formed by the following method steps;
- mounting the substrate on an electrically insulating cathode of larger area than the substrate;
- and
- applying D.C. power to produce a glow discharge, the exposed area of the cathode serving to maintain glow discharge and a dark space above the substrate.
A coated substrate formed in a glow discharge chamber in accordance with the following fabrication steps:
- providing an electrically conducting cathode within a chamber of larger area than that of the substrate;
- mounting the substrate onto the cathode thereby covering a portion of the cathode and leaving a portion of the cathode exposed;
- substantially evaculating any air from within the chamber;
- admitting into the chamber a gas containing silicon molecules;
- applying a D.C. voltage to the cathode causing a glow discharge at the exposed portion of the cathode, the flow of electrons during the glow discharge reducing any positive charge accumulation at the substrate, thereby forming a thin bonding layer of silicon on the substrate;
- removing the gas containing silicon molecules from the chamber;
- admitting a hydrocarbon gas into the chamber;
- maintaining the temperature of the substrate to less than 300.degree. C.;
- and
- applying a D.C. voltage to the cathode causing a glow discharge at the exposed portion of the cathode, the flow of electrons during the glow discharge reducing any positive charge accumulation at the substrate, thereby forming a thin bonding layer of silicon on the substrate;
- removing the gas containing silicon molecules from the chamber;
- admitting a hydrocarbon gas into the chamber;
- maintaining the temperature of the substrate to less than 300.degree. C.;
- and
- applying a D.C. voltage to the cathode causing a glow discharge at the exposed portion of the cathode, the flow of electrons during glow discharge reducing any positive charge accumulation at the substrate, thereby forming a coating on the substrate of infra red transparent hard carbon.
A method of depositing a coating on an electrically insulating material substrate in a glow discharge chamber comprising the steps of;
- providing an electrically conducting cathode, within the chamber, of larger area than that of the substrate;
- mounting the substrate onto the cathode thereby covering a portion of the cathode and leaving a portion of the cathode exposed;
- substantially evacuating any air from within the chamber;
- admitting a gas containing molecules of a coating material into the chamber;
- maintaining the temperature of the substrate to less than 300.degree. C.;
- and
- applying a D.C. voltage to the cathode causing a glow discharge at the exposed portion of the cathode, the flow of electrons during glow discharge reducing any positive charge accumulation at the substrate, thereby forming a coating on the substrate.
Dependencies are inferred from the claim text.