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
  • C23C16/22—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
• • 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
  • C23C16/02—Pretreatment of the material to be coated
  • C23C16/0272—Deposition of sub-layers, e.g. to promote the adhesion of the main coating
• • 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
  • C23C16/27—Diamond only
  • C23C16/271—Diamond only using hot filaments
• • 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
  • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
  • C23C28/04—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material
  • C23C28/042—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material including a refractory ceramic layer, e.g. refractory metal oxides, ZrO2, rare earth oxides
• • 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
  • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
  • C23C28/04—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material
  • C23C28/046—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings of inorganic non-metallic material with at least one amorphous inorganic material layer, e.g. DLC, a-C:H, a-C:Me, the layer being doped or not
• • 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
  • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
  • C23C28/30—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer
  • C23C28/34—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates
  • C23C28/341—Coatings combining at least one metallic layer and at least one inorganic non-metallic layer including at least one inorganic non-metallic material layer, e.g. metal carbide, nitride, boride, silicide layer and their mixtures, enamels, phosphates and sulphates with at least one carbide layer
• • 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
  • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C8/60—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using solids, e.g. powders, pastes
  • C23C8/62—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using solids, e.g. powders, pastes only one element being applied
  • C23C8/64—Carburising
• • 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
  • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
  • C23C8/80—After-treatment
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B28/00—Production of homogeneous polycrystalline material with defined structure
  • C30B28/12—Production of homogeneous polycrystalline material with defined structure directly from the gas state
  • C30B28/14—Production of homogeneous polycrystalline material with defined structure directly from the gas state by chemical reaction of reactive gases
• • C—CHEMISTRY; METALLURGY
  • C30—CRYSTAL GROWTH
  • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
  • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
  • C30B29/02—Elements
  • C30B29/04—Diamond

Definitions

• the present invention relates to a diamond film deposited substrate and a method for manufacturing a diamond film deposited substrate.
• Conductive diamond has a wide potential window in aqueous and non-aqueous systems and low background current, so it is known as an electrode material that enables highly sensitive electrochemical detection over a wide potential range.
• Patent Document 1 discloses that at least the surface of an electrode base material comprising a valve metal selected from the group consisting of niobium, tantalum, titanium, and zirconium and a material selected from metal-based alloys thereof is plastically worked. and then heat-treating the electrode base material in a vacuum or an inert atmosphere to form a conductive diamond film on the surface of the heat-treated electrode base material.
• a manufacturing method is disclosed.
• An object of the present invention is to provide a diamond film deposited substrate that can improve the durability of a diamond electrode.
• a method of manufacturing a diamond film deposited substrate comprising the step of depositing a conductive diamond film on the niobium carbide layer.
• FIG. 1 is a schematic diagram showing a cross section of a diamond film deposited substrate 10 according to a first embodiment of the present invention.
• FIG. 2 is a flowchart showing an example of a method for manufacturing the diamond film deposited substrate 10 according to the first embodiment of the present invention.
• FIG. 3(a) is a schematic diagram illustrating the processing damage layer forming step S102 of the first embodiment of the present invention
• FIG. 3(b) is a schematic diagram illustrating the carbon source embedding step S103 of the first embodiment of the present invention. It is a schematic diagram for explaining.
• FIG. 4 is a schematic diagram showing a cross section of a diamond film deposited substrate 10 according to a modification of the first embodiment of the present invention.
• FIG. 5(a) is a surface photograph of sample 1 of the example of the present invention
• FIG. 5(b) is a surface photograph of sample 2 of the example of the present invention
• FIG. 5(c) is a photograph of the surface of sample 2 of the example of the present invention
• FIG. 5(d) is a surface photograph of Sample 3 of Example of the present invention
• FIG. 5(d) is a surface photograph of Sample 4 of Example of the present invention.
• Diamond electrodes that are made conductive by containing boron or the like can be used to generate oxidizing agents such as ozone. Durability is a major issue in such diamond electrodes. Although the adhesion and peel strength between the substrate and the diamond film have been improved by the techniques described in Patent Document 1 and the like, it has been found that it is difficult to obtain a practical level of durability.
• the inventor of the present application has conducted extensive research on the carbide layer described above.
• the carbide layer impedes the durability of the diamond electrode only when a strongly acidic liquid comes into contact with the carbide layer, and pinholes that reach the base material or the carbide layer exist on the surface of the diamond film.
• the problem lies in the fact that It has also been found that by daring to form a continuous carbide layer as an intermediate layer, the occurrence of the above-mentioned pinholes can be suppressed.
• a processing damage layer with micro-cracks is formed, and a carbon source is embedded inside the processing damage layer and heat treatment is performed. It was found that it is effective to apply
• the diamond film deposited substrate 10 of this embodiment is preferably used, for example, to manufacture a diamond electrode for electrochemical reactions (for example, for ozone generation). Thereby, it is possible to suppress deterioration of the diamond electrode due to electrical conduction and improve durability.
• FIG. 1 is a schematic diagram showing a cross section of a diamond film deposited substrate 10 of this embodiment.
• a diamond film deposition substrate 10 includes, for example, a substrate 20, a niobium carbide layer 30, and a conductive diamond film 40.
• the substrate 20 is, for example, a flat metal niobium plate material on which the conductive diamond film 40 is deposited and for supporting the conductive diamond film 40.
• the size and thickness of the main surface of the substrate 20 are not particularly limited, for example, the main surface has a rectangular shape with one side of 20 mm or more and 500 mm or less, and the thickness is 0.5 mm or more and 5 mm or less.
• the niobium carbide layer 30 is formed, for example, on at least one main surface of the substrate 20, and is a layer formed by a reaction between a part of the metal niobium of the substrate 20 and a carbon source 22, which will be described later.
• the niobium carbide layer 30 functions, for example, as an intermediate layer for increasing the nucleation density of diamond crystals.
• the thickness of the niobium carbide layer 30 is preferably, for example, 0.5 ⁇ m or more and 5 ⁇ m or less (more preferably 0.8 ⁇ m or more and 2.5 ⁇ m or less). That is, it is preferable that the maximum thickness and minimum thickness of the niobium carbide layer 30 fall within the range of 0.5 ⁇ m or more and 5 ⁇ m or less (more preferably 0.8 ⁇ m or more and 2.5 ⁇ m or less). If the thickness of the niobium carbide layer 30 is less than 0.5 ⁇ m, the nucleation density of diamond crystals for forming the conductive diamond film 40 may be insufficient.
• the thickness of the niobium carbide layer 30 by setting the thickness of the niobium carbide layer 30 to 0.5 ⁇ m or more, the density of diamond crystal nucleation for forming the conductive diamond film 40 can be sufficiently increased.
• the thickness of the niobium carbide layer 30 exceeds 5 ⁇ m, internal stress becomes large and the diamond film deposited substrate 10 may warp.
• the thickness of the niobium carbide layer 30 by setting the thickness of the niobium carbide layer 30 to 5 ⁇ m or less, internal stress can be reduced and warpage of the diamond film deposited substrate 10 can be reduced.
• the conductive diamond film 40 is, for example, a conductive polycrystalline film formed on the niobium carbide layer 30.
• the conductive diamond film 40 may be either a polycrystalline diamond film or a diamond-like carbon (DLC) film.
• the conductive diamond film 40 preferably contains boron at a concentration of, for example, 1 ⁇ 10 19 cm ⁇ 3 or more and 1 ⁇ 10 22 cm ⁇ 3 or less.
• the thickness of the conductive diamond film 40 is, for example, 0.5 ⁇ m or more and 10 ⁇ m or less, and preferably 1 ⁇ m or more and 5 ⁇ m or less from the viewpoint of maintaining a balance between durability and cost. In this embodiment, a case will be described in which the conductive diamond film 40 has a single layer structure.
• the surface of the conductive diamond film 40 is observed using, for example, a scanning electron microscope (for example, 5000x magnification), there are pinholes that reach the substrate 20 or the niobium carbide layer 30 within a field of view of 20 ⁇ m x 20 ⁇ m. do not. Thereby, for example, even if the diamond electrode is used in a strongly acidic liquid, the risk of the strongly acidic liquid coming into contact with the niobium carbide layer 30 can be reduced, so it is possible to improve the durability of the diamond electrode.
• a scanning electron microscope for example, 5000x magnification
• the substrate 2 when the cross section (vertical section or cross section) of the conductive diamond film 40 is observed using, for example, a scanning electron microscope (for example, 5000x magnification), the substrate 2 Alternatively, it is preferable that there be no pinholes that reach the niobium carbide layer 30. In other words, in the conductive diamond film 40, not only pinholes observable from the surface but also internal pinholes are reduced. This makes it possible to further improve the durability of the diamond electrode. In addition, in the cross section (vertical cross section or cross section) of the conductive diamond film 40, it is more preferable that there is no pinhole that reaches the substrate 20 or the niobium carbide layer 30 within a field of view of 1 mm x 1 mm. It is particularly preferable that no pinholes exist over the entire cross section.
• a width of 20 ⁇ m or more (length in the direction parallel to the main surface of the substrate 20) is observed.
• a continuous niobium carbide layer 30 with a thickness of 0.5 ⁇ m or more is formed. This makes it possible to sufficiently increase the nucleation density of diamond crystals for forming the conductive diamond film 40 and to suppress the generation of pinholes. Note that from the viewpoint of further suppressing the generation of pinholes, it is more preferable that a continuous niobium carbide layer 30 with a thickness of 0.5 ⁇ m or more is formed over a width of 1 mm or more. It is particularly preferable that a continuous niobium carbide layer 30 with a thickness of 0.5 ⁇ m or more is formed over the entire surface.
• the main component of the niobium carbide layer 30 is preferably niobium carbide having the chemical formula NbC, for example. Thereby, the density of diamond crystal nucleation for forming the conductive diamond film 40 can be increased.
• the main components of the niobium carbide layer 30 can be confirmed by, for example, X-ray diffraction (XRD).
• the crystallite diameter of niobium carbide contained in the niobium carbide layer 30 is preferably, for example, 1 nm or more and 60 nm or less. If the crystallite diameter is outside the above range, it may be difficult to form a continuous niobium carbide layer 30 with a thickness of 0.5 ⁇ m or more. On the other hand, by setting the crystallite diameter within the above range, it becomes easier to form a continuous niobium carbide layer 30 with a thickness of 0.5 ⁇ m or more, and as a result, it becomes easier to suppress the generation of pinholes. Note that each crystallite diameter in this specification can be measured, for example, by the Scherrer method of XRD.
• the crystallite diameter of the metal niobium (particularly the metal niobium present near the interface with the niobium carbide layer 30) contained in the substrate 20 is preferably, for example, 30 nm or more and 90 nm or less. If the crystallite diameter of metallic niobium is less than 30 nm, it may be difficult to form a continuous niobium carbide layer 30. On the other hand, by setting the crystallite diameter of metal niobium to 30 nm or more, continuous niobium carbide layer 30 is easily formed.
• the crystallite diameter of niobium metal exceeds 90 nm, the difference in crystallite diameter between niobium carbide and niobium carbide contained in the niobium carbide layer 30 becomes large, and cracks and the like may occur.
• the crystallite diameter of metallic niobium is distributed so that it gradually becomes smaller from the substrate 20 to the niobium carbide layer 30, so it is possible to suppress the occurrence of cracks, etc. can.
• the diamond film deposited substrate 10 of this embodiment can be used to manufacture a diamond electrode for electrochemical reactions (for example, for ozone generation), and therefore the present invention provides a method for manufacturing a diamond electrode. It is also applicable as
• FIG. 2 is a flowchart showing an example of a method for manufacturing the diamond film deposited substrate 10 of this embodiment.
• the method for manufacturing the diamond film deposited substrate 10 of this embodiment includes, for example, an unevenness forming step S101, a processing damage layer forming step S102, a carbon source embedding step S103, a seeding step S104, It includes a niobium carbide layer forming step S105 and a diamond film depositing step S106.
• a diamond film deposited substrate 10 is manufactured from a substrate 20 made of metal niobium.
• the unevenness forming step S101 is, for example, a process of forming unevenness on at least one main surface of the substrate 20. Thereby, peeling due to the difference in thermal expansion coefficient between the substrate 20 and the conductive diamond film 40 can be suppressed. In other words, the peel strength of the diamond film deposited substrate 10 can be further improved.
• the unevenness forming step S101 it is preferable to form the unevenness so that the arithmetic mean roughness Ra (see JIS B0601-2001) of the main surface is, for example, 0.5 ⁇ m or more and 10 ⁇ m or less.
• known methods such as grinding, blasting, wet etching, dry etching, etc. can be used as a process for forming irregularities.
• the unevenness forming step S101 is performed, for example, before the processing damage layer forming step S102. If the surface on which the processing damage layer 21 is formed is processed to create irregularities, there is a possibility that the processing damage layer 21 will be removed. On the other hand, by performing the unevenness forming step S101 before the processing damaged layer forming step S102, work hardening occurs in the substrate 20, so that microcracks are easily formed in the processing damaged layer forming step S102. In addition, in the unevenness forming step S101, machining such as punching or groove processing may be further performed in order to further cause work hardening of the substrate 20.
• the unevenness forming step S101 may be omitted.
• the niobium carbide layer forming step S105 can be performed by performing the processing damage layer forming step S102 and the carbon source embedding step S103, which will be described later.
• a niobium carbide layer 30 that continuously covers the main surface of the substrate 20 can be formed. That is, the generation of pinholes in the conductive diamond film 40 can be suppressed.
• FIG. 3A is a schematic diagram illustrating the processing damage layer forming step S102.
• the processing damage layer forming step S102 is performed by introducing processing damage onto at least one main surface of the substrate 20 (the surface with the unevenness formed in the unevenness forming step S101). This is a step of forming a process-damaged layer 21 having a large number of microcracks.
• heating exceeding 2,300 degrees is normally required, but by forming the processing damage layer 21, heating at a low temperature (for example, around 800 degrees) is required.
• the method of introducing processing damage is not particularly limited as long as it is a method that can form microcracks.
• processing damage can be introduced by grinding, imprinting, blasting, pressing, etc. to form the processing damage layer 21 having microcracks.
• microcracks are not only cracks with a length of 0.1 ⁇ m or more and 2 ⁇ m or less and a width of 5 nm or more and 200 nm or less (hereinafter also referred to as microcracks with voids), but also cracks with a high density of crystal defects.
• microcracks without voids
• the main surface of the substrate 20 may be observed using a scanning electron microscope.
• the processing damage layer forming step S102 it is preferable to form the processing damage layer 21 with a thickness of, for example, 0.5 ⁇ m or more and 5 ⁇ m or less (more preferably 0.8 ⁇ m or more and 2.5 ⁇ m or less).
• a thickness of, for example, 0.5 ⁇ m or more and 5 ⁇ m or less more preferably 0.8 ⁇ m or more and 2.5 ⁇ m or less.
• the niobium carbide layer forming step S105 which will be described later, at least a part of the processing damage layer 21 becomes the niobium carbide layer 30, so by setting the thickness of the processing damage layer 21 within the above range, niobium of an appropriate thickness can be formed. It becomes easier to form the carbide layer 30.
• the thickness of the process-damaged layer 21 for example, a region where the crystallite diameter is 10% or more smaller than the crystallite diameter of metal niobium before forming the process-damaged layer 21 is defined as the process-damaged layer. It may also be layer 21.
• the process damage layer forming step S102 it is preferable to introduce process damage such that, for example, the crystallite diameter of metal niobium in the process damage layer 21 is 1 nm or more and 25 nm or less. If the crystallite diameter of the metal niobium in the process-damaged layer 21 exceeds 25 nm, it may be difficult for the carbon source 22 to diffuse into the process-damage layer 21, making it difficult to form a continuous niobium carbide layer 30. On the other hand, by setting the crystallite diameter of the metal niobium in the processing damage layer 21 to 25 nm or less, the surface area of the metal niobium becomes sufficiently large, so that it becomes easier to form the continuous niobium carbide layer 30.
• the crystallite diameter of the niobium metal in the processing damage layer 21 is less than 1 nm, it is possible to form a continuous niobium carbide layer 30; is technically difficult and increases the cost significantly, so from the viewpoint of cost reduction, it is preferable that the crystallite diameter of the metal niobium in the processing damage layer 21 is 1 nm or more.
• FIG. 3(b) is a schematic diagram illustrating the carbon source embedding step S103.
• the carbon source embedding step S103 is a step of embedding a carbon source 22 made of solid carbon or a carbon compound inside the processing damaged layer 21 (for example, inside a micro crack with a void). It is. Since the processing damage layer 21 has many microcracks, the carbon source 22 can be easily embedded therein. Specifically, for example, by sprinkling the carbon source 22 on the surface of the substrate 20 and rubbing the surface with the substrate 20 etc. of the same size, the carbon source 22 is cracked to the same size as the micro cracks (for example, an average particle diameter of 200 nm).
• the carbon source 22 for example, graphite, boron carbide, diamond powder, etc. can be used.
• diamond powder is used as the carbon source 22
• sp 2 carbon amorphous layer
• the average particle size of the carbon source 22 is preferably 200 nm or less. This makes it easier to embed the carbon source 22 inside the process-damaged layer 21. Moreover, the surface area of the carbon source 22 becomes large, and the reactivity with metal niobium can be improved. Note that the lower limit of the average particle size of the carbon source 22 is not particularly limited, but is, for example, 5 nm or more.
• the carbon source 22 when graphite (average particle size 5 to 200 nm) is embedded into the processing damage layer 21 as the carbon source 22, for example, the carbon source 22 of 0.1 ⁇ g/cm 2 or more and 10 ⁇ g/cm 2 or less is used. Preferably, it is embedded. If the amount of the embedded carbon source 22 is less than 0.1 ⁇ g/cm 2 , the carbonization of metal niobium will be insufficient, and it may be difficult to form a continuous niobium carbide layer 30 .
• the amount of the embedded carbon source 22 is set to 0.1 ⁇ g/cm 2 or more, the metal niobium can be sufficiently carbonized and the continuous niobium carbide layer 30 can be easily formed.
• the amount of the embedded carbon source 22 exceeds 10 ⁇ g/cm 2 , a large amount of the carbon source 22 may remain after the niobium carbide layer 30 is formed, which may adversely affect the deposition of the conductive diamond film 40. There is.
• the amount of embedded carbon source 22 is set to 10 ⁇ g/cm 2 or less, the remaining carbon source 22 can be reduced.
• the carbon source 22 is embedded within a depth of 1 ⁇ m or less.
• the seeding step S104 is, for example, a step of seeding diamond particles onto the main surface of the substrate 20 (the main surface on which the processing damage layer 21 is formed, that is, the surface of the processing damage layer 21).
• the energy barrier required for initial nucleation to form the conductive diamond film 40 can be lowered.
• known methods such as blasting and dipping can be used.
• the seeding step S104 is preferably performed, for example, before forming the niobium carbide layer 30 (that is, before the niobium carbide layer forming step S105).
• the niobium carbide layer forming step S105 and the diamond film depositing step S106 which will be described later, can be performed continuously in the same apparatus.
• the seeding step S104 may be performed simultaneously with the above-mentioned carbon source embedding step S103.
• the same diamond particles can serve as the carbon source 22 used in the carbon source embedding step S103 and the diamond particles used in the seeding step S104.
• the carbon source 22 preferably includes sp 2 carbon.
• a diamond particle for example, a nanodiamond particle obtained by a detonation method in which the periphery of the core portion of the diamond structure (sp 3 structure) is covered with an amorphous layer (sp 2 carbon) is This is preferable because the 2 carbon is exhausted and the core of the sp 3 structure can remain as a seeded diamond particle.
• the seeding step S104 may be omitted.
• the above-mentioned processing damage layer forming step S102 and carbon source embedding step S103 are performed, so that the niobium carbide layer forming step S105 is performed.
• a niobium carbide layer 30 that continuously covers the main surface of the substrate 20 can be formed. That is, the generation of pinholes in the conductive diamond film 40 can be suppressed.
• the niobium carbide layer forming step S105 is a step of forming a niobium carbide layer 30 that continuously covers the main surface of the substrate 20 by subjecting the processing damaged layer 21 to a heat treatment and reacting the metal niobium and the carbon source 22. Thereby, the generation of pinholes on the surface of the conductive diamond film 40 can be suppressed.
• the structure is reconstructed simultaneously with the formation of the niobium carbide layer 30, and most of the microcracks formed in the processing damage layer forming step S102 disappear.
• defects are eliminated and reduced by solid-phase diffusion at grain boundaries, so that the machining damage is recovered to some extent and the strength is increased.
• the niobium carbide layer 30 can be formed using, for example, a hot filament CVD apparatus described below as a heating furnace for heat treatment.
• Examples of the conditions for the heat treatment in the niobium carbide layer forming step S105 are as follows. Heat treatment temperature (substrate temperature): 550 to 850 degrees Pressure: 10 to 50 Torr Heat treatment time: 30-120 minutes
• the niobium carbide layer forming step S105 it is preferable to form the niobium carbide layer 30 having a thickness of, for example, 10% or more and 100% or less (more preferably 30% or more and 100% or less) of the processing damage layer 21. In other words, it is preferable that a depth range from the surface to 10% or more of the thickness of the processing damage layer 21 is reacted with the carbon source 22 to form the niobium carbide layer 30. If the thickness of the niobium carbide layer 30 is less than 10% of the thickness of the machining damage layer 21, the nucleation density of diamond crystals will be insufficient, which may cause pinholes.
• the thickness of the niobium carbide layer 30 is set to 10% or more of the thickness of the processing damage layer 21, the density of diamond crystal nucleation can be sufficiently increased. Note that when all of the process-damaged layer 21 is reacted with the carbon source 22, the thickness of the niobium carbide layer 30 becomes equal to the thickness of the process-damage layer 21.
• the niobium carbide layer forming step S105 it is preferable to form the niobium carbide layer 30 whose main component is, for example, niobium carbide having the chemical formula NbC. Thereby, the density of diamond crystal nucleation for forming the conductive diamond film 40 can be increased.
• the niobium carbide layer forming step S105 it is preferable to form the niobium carbide layer 30 so that, for example, the crystallite diameter of niobium carbide contained in the niobium carbide layer 30 is 1 nm or more and 60 nm or less. This makes it easier to suppress the occurrence of pinholes.
• the diamond film deposition step S106 is, for example, a step of depositing a conductive diamond film 40 on the niobium carbide layer 30.
• the conductive diamond film 40 can be deposited using, for example, a hot filament CVD apparatus.
• the hot filament CVD apparatus is configured to be able to supply various gases such as hydrogen gas, carbon-containing gas, and boron-containing gas to the growth chamber.
• Methane gas or ethane gas can be used as the carbon-containing gas.
• boron-containing gas trimethyl boron (TMB) gas, trimethyl borate gas, triethyl borate gas, or diborane gas can be used.
• TMB trimethyl boron
• the hot filament CVD apparatus includes a temperature sensor, a tungsten filament, an electrode (for example, a molybdenum electrode), etc. in an airtight container configured inside the growth chamber.
• the diamond film deposited substrate 10 can be manufactured.
• the diamond film deposited substrate 10 may be divided into predetermined sizes to manufacture a plurality of diamond electrodes.
• the thickness is 0.5 ⁇ m or more over a width of 20 ⁇ m or more.
• a continuous niobium carbide layer 30 is formed. This makes it possible to sufficiently increase the nucleation density of diamond crystals for forming the conductive diamond film 40 and to suppress the generation of pinholes. Note that from the viewpoint of further suppressing the generation of pinholes, it is more preferable that a continuous niobium carbide layer 30 with a thickness of 0.5 ⁇ m or more is formed over a width of 1 mm or more. It is particularly preferable that a continuous niobium carbide layer 30 with a thickness of 0.5 ⁇ m or more is formed over the entire surface.
• the thickness of the niobium carbide layer 30 is preferably, for example, 0.5 ⁇ m or more and 5 ⁇ m or less (more preferably 0.8 ⁇ m or more and 2.5 ⁇ m or less). . That is, it is preferable that the maximum thickness and minimum thickness of the niobium carbide layer 30 fall within the range of 0.5 ⁇ m or more and 5 ⁇ m or less (more preferably 0.8 ⁇ m or more and 2.5 ⁇ m or less). If the thickness of the niobium carbide layer 30 is less than 0.5 ⁇ m, the nucleation density of diamond crystals for forming the conductive diamond film 40 may be insufficient.
• the thickness of the niobium carbide layer 30 by setting the thickness of the niobium carbide layer 30 to 0.5 ⁇ m or more, the density of diamond crystal nucleation for forming the conductive diamond film 40 can be sufficiently increased.
• the thickness of the niobium carbide layer 30 exceeds 5 ⁇ m, internal stress becomes large and the diamond film deposited substrate 10 may warp.
• the thickness of the niobium carbide layer 30 by setting the thickness of the niobium carbide layer 30 to 5 ⁇ m or less, internal stress can be reduced and warpage of the diamond film deposited substrate 10 can be reduced.
• the main component of the niobium carbide layer 30 is preferably niobium carbide with the chemical formula NbC, for example. Thereby, the density of diamond crystal nucleation for forming the conductive diamond film 40 can be increased.
• the crystallite diameter of niobium carbide contained in the niobium carbide layer 30 is preferably, for example, 1 nm or more and 60 nm or less. If the crystallite diameter is outside the above range, it may be difficult to form a continuous niobium carbide layer 30 with a thickness of 0.5 ⁇ m or more. On the other hand, by setting the crystallite diameter within the above range, it becomes easier to form a continuous niobium carbide layer 30 with a thickness of 0.5 ⁇ m or more, and as a result, it becomes easier to suppress the generation of pinholes.
• the crystallite diameter of the metal niobium (particularly the metal niobium present near the interface with the niobium carbide layer 30) contained in the substrate 20 is, for example, 30 nm or more and 90 nm or less. It is preferable that If the crystallite diameter of niobium metal is less than 30 nm, it may be difficult to form a continuous niobium carbide layer 30. On the other hand, by setting the crystallite diameter of metal niobium to 30 nm or more, continuous niobium carbide layer 30 is easily formed.
• the crystallite diameter of niobium metal exceeds 90 nm, the difference in crystallite diameter between niobium carbide and niobium carbide contained in the niobium carbide layer 30 becomes large, and cracks and the like may occur.
• the crystallite diameter of metallic niobium is distributed so that it gradually becomes smaller from the substrate 20 to the niobium carbide layer 30, so it is possible to suppress the occurrence of cracks, etc. can.
• the method for manufacturing the diamond film deposited substrate 10 of this embodiment includes, for example, a processing damage layer forming step S102, a carbon source embedding step S103, a niobium carbide layer forming step S105, and a diamond film depositing step S106. have.
• a continuous niobium carbide layer 30 can be formed, making it possible to suppress the generation of pinholes on the surface of the conductive diamond film 40.
• the niobium carbide layer forming step S105 at least a part of the processing damage layer 21 becomes the niobium carbide layer 30, so by setting the thickness of the processing damage layer 21 within the above range, the niobium carbide layer has an appropriate thickness. 30 becomes easier to form.
• the niobium carbide layer forming step S105 for example, 10% or more and 100% or less (more preferably 30% or more and 100% or less) of the processing damage layer 21.
• the niobium carbide layer 30 is formed to have a thickness of .
• a depth range from the surface to 10% or more of the thickness of the processing damage layer 21 is reacted with the carbon source 22 to form the niobium carbide layer 30. If the thickness of the niobium carbide layer 30 is less than 10% of the thickness of the machining damage layer 21, the nucleation density of diamond crystals will be insufficient, which may cause pinholes.
• the thickness of the niobium carbide layer 30 by setting the thickness of the niobium carbide layer 30 to 10% or more of the thickness of the processing damage layer 21, the density of diamond crystal nucleation can be sufficiently increased.
• the process damage is removed such that the crystallite diameter of metal niobium in the process damage layer 21 is 1 nm or more and 25 nm or less. It is preferable to introduce If the crystallite diameter of the metal niobium in the process-damaged layer 21 exceeds 25 nm, it may be difficult for the carbon source 22 to diffuse into the process-damage layer 21, making it difficult to form a continuous niobium carbide layer 30.
• the crystallite diameter of the metal niobium in the processing damage layer 21 is 1 nm or more.
• the method for manufacturing the diamond film deposited substrate 10 of this embodiment includes a seeding step S104. By interposing diamond particles at the interface between the niobium carbide layer 30 and the conductive diamond film 40, the energy barrier required for initial nucleation to form the conductive diamond film 40 can be lowered.
• the method for manufacturing the diamond film deposited substrate 10 of this embodiment includes an unevenness forming step S101. Thereby, peeling due to the difference in thermal expansion coefficient between the substrate 20 and the conductive diamond film 40 can be suppressed. In other words, the peel strength of the diamond film deposited substrate 10 can be improved.
• FIG. 4 is a schematic diagram showing a cross section of the diamond film deposited substrate 10 of this modification.
• the diamond film deposition substrate 10 of this modification includes, for example, a substrate 20, a niobium carbide layer 30, and a conductive diamond film 40, and the niobium carbide layer 30 has an upper part. 31 and a lower part 32.
• the main component of the upper part 31 of the niobium carbide layer 30 is niobium carbide with the chemical formula NbC
• the lower part 32 of the niobium carbide layer 30 includes niobium carbide with the chemical formula Nb 2 C. Since the niobium carbide layer 30 is carbonized from the surface side, Nb 2 C with a large Nb component is likely to be formed in the lower part 32 where there is less carbon source 22 diffusing from the surface side. Even when the lower part 32 of the niobium carbide layer 30 contains Nb 2 C as in this modification, the formation of the continuous niobium carbide layer 30 makes it easier to form the conductive diamond film 40. Since the nucleation density of diamond crystals can be sufficiently increased and the generation of pinholes can be suppressed, the durability of the diamond electrode can be improved as a result.
• the ratio of the thickness of the upper part 31 and the lower part 32 of the niobium carbide layer 30 is not particularly limited, but for example, the thickness of the lower part 32 of the niobium carbide layer 30 is 50% or more and 150% or less of the thickness of the upper part 31.
• the crystallite diameter of niobium carbide contained in the upper part 31 of the niobium carbide layer 30 is smaller than the crystallite diameter of niobium carbide contained in the lower part 32.
• the crystallite diameter of niobium carbide contained in the upper part 31 is 1 nm or more and 25 nm or less
• the crystallite diameter of niobium carbide contained in the lower part 32 is, for example, 20 nm or more and 60 nm or less.
• the crystallite diameter of niobium carbide contained in the upper part 31 is calculated from the peak of NbC (111) in XRD, and the crystallite diameter of niobium carbide contained in the lower part 32 is calculated from the peak of Nb 2 C (211) in XRD. Calculated from.
• the main component of the upper part 31 of the niobium carbide layer 30 is niobium carbide having the chemical formula NbC, and the lower part 32 of the niobium carbide layer 30 contains niobium carbide having the chemical formula Nb 2 C. Then, a niobium carbide layer 30 is formed.
• the process damage layer 21 is Processing damage may be introduced so that the crystallite diameter of the niobium metal in the upper part is smaller than the crystallite diameter of the niobium metal in the lower part.
• each process included in the method for manufacturing the diamond film deposited substrate 10 has been described, but it is not necessary to perform all the processes described above. Specifically, for example, one (or both) of the unevenness forming step S101 and the seeding step S104 may be omitted. In this case, as in the first embodiment, a continuous niobium carbide layer 30 can be formed to suppress pinholes in the conductive diamond film 40.
• the carbon source 22 is embedded, for example, inside the micro-cracks with voids, but the carbon source 22 is not necessarily formed inside the micro-cracks with voids. It is not necessary to embed the carbon source 22 therein.
• the crystallite diameter of metal niobium in the processing damage layer 21 sufficiently small (for example, 20 nm or less)
• many grain boundaries (microcracks without voids) where crystal defects are densely aggregated and arranged are formed. be able to.
• a sufficient diffusion path for the carbon source 22 can be secured, and the surface area of the metal niobium contributing to the carbonization reaction can be sufficiently increased.
• the niobium carbide layer 30 is introduced so as to be in contact with the surface of the niobium carbide 21, it is possible to form the niobium carbide layer 30. Even if the carbon source 22 is not embedded inside the microcracks with voids, it diffuses into the interior from the grain boundaries of metallic niobium (microcracks without voids), so the thickness is adjusted according to the diffusion length. It is possible to obtain a niobium carbide layer 30 of. However, from the viewpoint of making it easier to form a continuous niobium carbide layer 30 with a sufficient thickness (for example, 0.5 ⁇ m or more), it is necessary to use carbon inside microcracks with voids, as in the above embodiment. Preferably, the source 22 is implanted.
• the conductive diamond film 40 may have a laminated structure in which a plurality of conductive diamond layers are laminated.
• the conductive diamond film 40 even when the conductive diamond film 40 has a single layer structure as in the above embodiment, it is possible to suppress the generation of pinholes.
• a substrate 20 made of niobium metal was prepared and subjected to grinding.
• a vertical axis round table type device was used, and the grindstone was cubic boron carbide (grain size #600 or more). It was confirmed using a scanning electron microscope that a processing damage layer 21 having microcracks was formed on the main surface of the substrate 20 after the grinding process.
• the main surface of the substrate 20 after grinding was sprinkled with 7.5 mg/cm 2 of graphite (particle size 1 to 2 ⁇ m) as a carbon source 22, and the surface was rubbed against a substrate 20 of the same size.
• the amount of embedded graphite was measured before and after embedding, and it was found that 2.1 ⁇ g/cm 2 of graphite (particle size 5 to 45 nm) was embedded inside the processed damage layer 21 after rubbing together. confirmed.
• the main surface of the substrate 20 was measured by XRD, the crystallite diameter of the metal niobium in the processing damage layer 21 was 12.3 nm.
• each crystallite diameter in this example was calculated from the results of wide-angle X-ray diffraction measurement using an X-ray diffraction device (RINT2500HLB) manufactured by Rigaku Corporation.
• the measurement conditions were as follows. Measurement wavelength: CuK ⁇ (0.15418nm) X-ray output: 50kV-250mA
• Optical system Parallel beam with monochromator Diverging slit (DS): 0.5° + 10mmH Scattering slit (SS): 0.5°
• the substrate 20 with graphite embedded therein was placed in a hot filament CVD apparatus, and the formation of the niobium carbide layer 30 and the deposition of the conductive diamond film 40 were performed continuously. Specifically, hydrogen gas, methane gas, and TMB gas were introduced, and the pressure was set at 20 to 50 Torr. Thereafter, a voltage (120 to 150 V) was applied to the 40 cm filament and maintained until the filament was carbonized and the resistance became constant. Further, the voltage of the filament was increased to 175V, and the filament temperature was maintained at 2200 to 2400°C and the substrate temperature was 700 to 800°C for 180 minutes.
• the diamond film deposited substrate 10 was taken out from the hot filament CVD apparatus, and it was confirmed that a conductive diamond film 40 with a thickness of 3.32 ⁇ m was deposited. Further, when the diamond film deposited substrate 10 was measured by XRD from the conductive diamond film 40 side, the crystallite diameter of niobium metal was 85.6 nm, and the crystallite diameter of niobium carbide was 1.9 nm.
• Sample 2 Further, a diamond film deposited substrate 10 of Sample 2 was manufactured according to the following procedure.
• a substrate 20 made of niobium metal was prepared and subjected to the same grinding process as Sample 1. It was confirmed using a scanning electron microscope that a processing damage layer 21 having microcracks was formed on the main surface of the substrate 20 after the grinding process.
• sample 2 the carbon source 22 was not embedded, and the substrate 20 after grinding was placed in a hot filament CVD apparatus, and a niobium carbide layer 30 was formed and a conductive diamond film was formed under the same conditions as sample 1. 40 depositions were performed in succession.
• the diamond film deposited substrate 10 was taken out from the hot filament CVD apparatus, and it was confirmed that a conductive diamond film 40 with a thickness of 2.72 ⁇ m was deposited. Further, when the diamond film deposited substrate 10 was measured by XRD from the conductive diamond film 40 side, the crystallite diameter of metal niobium was 33.0 nm, and the crystallite diameter of niobium carbide was 6.9 nm.
• the processing damage layer 21 was not formed, and graphite (particle size 1 to 2 ⁇ m) as the carbon source 22 was sprinkled on the main surface of the substrate 20 made of niobium metal in an amount of 7.5 mg/cm 2 . , the surface was rubbed against a substrate 20 of the same size. It was confirmed that 1.2 ⁇ g/cm 2 of graphite was attached to the surface of the substrate 20 after rubbing together.
• the principal surface of the substrate 20 was measured by XRD, the crystallite diameter of metallic niobium was 26.1 nm.
• the rubbed substrate 20 was placed in a hot filament CVD apparatus, and under the same conditions as Sample 1, the formation of the niobium carbide layer 30 and the deposition of the conductive diamond film 40 were performed continuously.
• the diamond film deposited substrate 10 was taken out from the hot filament CVD apparatus, and it was confirmed that a conductive diamond film 40 with a thickness of 2.94 ⁇ m was deposited. Further, when the diamond film deposited substrate 10 was measured by XRD from the conductive diamond film 40 side, the crystallite diameter of metal niobium was 58.1 nm, and the crystallite diameter of niobium carbide was 25.7 nm.
• a substrate 20 made of metal niobium was prepared and blasted.
• a blasting material of silicon carbide (particle size #100) was used for the blasting process. It was confirmed using a scanning electron microscope that a processing damage layer 21 having microcracks was formed on the main surface of the substrate 20 after the grinding process.
• the main surface of the blasted substrate 20 was sprinkled with 7.5 mg/cm 2 of graphite (particle size 1 to 2 ⁇ m) as a carbon source 22, and the surface was rubbed against a substrate 20 of the same size.
• the amount of embedded graphite was measured before and after embedding, and it was found that 5.3 ⁇ g/cm 2 of graphite (particle size 5 to 70 nm) was embedded inside the processed damage layer 21 after rubbing together. confirmed.
• the main surface of the substrate 20 was measured by XRD, the crystallite diameter of the metal niobium in the processing damage layer 21 was 6.9 nm.
• the substrate 20 with embedded graphite was placed in a hot filament CVD apparatus, and under the same conditions as Sample 1, the formation of the niobium carbide layer 30 and the deposition of the conductive diamond film 40 were performed continuously.
• the diamond film deposited substrate 10 was taken out from the hot filament CVD apparatus, and it was confirmed that a conductive diamond film 40 with a thickness of 3.21 ⁇ m was deposited. Further, when the diamond film deposited substrate 10 was measured by XRD from the conductive diamond film 40 side, the crystallite diameter of metallic niobium was 63.1 nm, and the crystallite diameter of niobium carbide was 12.8 nm.
• a continuous niobium carbide layer 30 by forming a process-damaged layer 21 having microcracks on the main surface of the substrate 20 and embedding the carbon source 22 inside the process-damage layer 21. confirmed. Furthermore, it has been confirmed that by forming the continuous niobium carbide layer 30, the generation of pinholes on the surface of the conductive diamond film 40 can be suppressed.
• a diamond film deposited substrate in which, when the surface of the conductive diamond film is observed using a scanning electron microscope, there are no pinholes that reach the substrate or the niobium carbide layer within a field of view of 20 ⁇ m x 20 ⁇ m.
• Ru Preferably, there are no pinholes that reach the substrate or the niobium carbide layer within a field of view of 1 mm x 1 mm. Particularly preferably, there are no pinholes that reach the substrate or the niobium carbide layer over the entire surface of the conductive diamond film.
• the continuous niobium carbide layer with a thickness of 0.5 ⁇ m or more was formed over a width of 20 ⁇ m or more. More preferably, the continuous niobium carbide layer with a thickness of 0.5 ⁇ m or more is formed over a width of 1 mm or more. Particularly preferably, the continuous niobium carbide layer with a thickness of 0.5 ⁇ m or more is formed over the entire main surface.
• the diamond film deposited substrate according to supplementary note 1 or supplementary note 2 The thickness of the niobium carbide layer is 0.5 ⁇ m or more and 5 ⁇ m or less. More preferably, the thickness of the niobium carbide layer is 0.8 ⁇ m or more and 2.5 ⁇ m or less.
• the main component of the upper part of the niobium carbide layer is niobium carbide with the chemical formula NbC, and the lower part of the niobium carbide layer includes niobium carbide with the chemical formula Nb2C .
• a method of manufacturing a diamond film deposited substrate comprising the step of depositing a conductive diamond film on the niobium carbide layer.
• Appendix 9 A method for manufacturing a diamond film deposited substrate according to appendix 8, comprising: In the step of forming the process damage layer, the process damage layer is formed with a thickness of 0.5 ⁇ m or more and 5 ⁇ m or less. More preferably, a process-damaged layer with a thickness of 0.8 ⁇ m or more and 2.5 ⁇ m or less is formed.
• Appendix 11 A method for manufacturing a diamond film deposited substrate according to any one of appendices 8 to 10, comprising: In the process of forming the process damage layer, process damage is introduced so that the crystallite diameter of metal niobium in the process damage layer is 1 nm or more and 25 nm or less.
• Appendix 12 A method for manufacturing a diamond film deposited substrate according to any one of appendices 8 to 11, comprising: The method further includes the step of seeding the main surface with diamond particles before forming the niobium carbide layer.
• Appendix 13 A method for manufacturing a diamond film deposited substrate according to any one of appendices 8 to 12, comprising: The method further includes the step of processing the main surface to form irregularities before forming the processing damage layer.
• Appendix 14 A method for manufacturing a diamond film deposited substrate according to any one of appendices 8 to 13, comprising: In the step of forming the niobium carbide layer, a niobium carbide layer whose main component is niobium carbide having the chemical formula NbC is formed.
• Appendix 16 A method for manufacturing a diamond film deposited substrate according to any one of appendices 8 to 15, comprising: In the step of forming the niobium carbide layer, the niobium carbide layer is formed so that the crystal grain size of niobium carbide contained in the niobium carbide layer is 1 nm or more and 60 nm or less.
• Diamond film deposition substrate 20 Substrate 21 Processing damage layer 22 Carbon source 30 Niobium carbide layer 31 Upper part 32 Lower part 40 Conductive diamond film S101 Unevenness forming step S102 Processing damage layer forming step S103 Carbon source embedding step S104 Seeding step S105 Niobium carbide layer Formation step S106 Diamond film deposition step

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