# US 4,393,097 A · Electrically conductive Si.sub.3 N.sub.4 -C series amorphous material and a method of producing the same

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- Number: US 4,393,097 A
- Document ID: US4393097A
- Status: Granted
- Kind: A
- Application number: 06/170,168
- Filed: 1980-07-18
- Granted: 1983-07-12
- Earliest claimed: 1979-07-24
- Inventors: Toshio Hirai; Takashi Goto
- Web page: https://patentgrep.com/patent/US4393097A

## CPC

- C04B 41/009: {characterised by the material treated}
- C04B 41/5066: {Silicon nitride}
- C04B 41/87: Ceramics
- C23C 16/22: characterised by the deposition of inorganic material, other than metallic material
- C23C 16/36: Carbonitrides
- H01B 1/18: the conductive material comprising carbon-silicon compounds, carbon or silicon
- Y10T 428/2918: including free carbon or carbide or therewith [not as steel]
- Y10T 428/30: Self-sustaining carbon mass or layer with impregnant or other layer
- C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE
- 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 (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- H01B: CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES (selection for magnetic properties H01F1/00; waveguides H01P {; printed circuits H05K})
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Electrically conductive Si.sub.3 N.sub.4 -C series amorphous material having excellent thermal and mechanical characteristics is produced in a massive size by chemical vapor deposition.

## Claims

### Claim 1

A method of producing massive and pure Si.sub.3 N.sub.4 -C series amorphous material composed of a deposited amorphous Si.sub.3 N.sub.4 matrix and codeposited carbon uniformly distributed in said matrix, having an electrical conductivity .sigma. of a formula
.sigma.=.sigma..sub.o exp(-E/2kT)
wherein .sigma..sub.o is an electrical conductivity at 0.degree. K., E is a value of 0.02-0.06 eV, k is the Boltzmann constant and T is an absolute temperature, a carbon content of about 0.2-10% by weight, an electrical conductivity .sigma. of about 10.sup.-3 to 10.sup.-1 .OMEGA..sup.-1 cm.sup.-1 at a temperature from ambient to about 900.degree. C., a density of about 2.7 to 3.0 g/cm.sup.3, a thermal conductivity of about 0.004-0.010 cal/cm.multidot.sec.multidot.K at ambient temperature, a specific heat of about 0.16 cal/g.multidot.K at ambient temperature, a thermal diffusivity of about 0.010-0.022 cm.sup.2 /sec at ambient temperature, and a micro Vickers hardness of about 2,500-3,500 kg/mm.sup.2 (100 g load) at ambient temperature by chemical vapor deposition process, which comprises reacting SiCl.sub.4 as silicon source gas, a nitrogen source gas and a hydrogen source gas with a carbon source gas at a deposition condition of a deposition temperature of about 1,100.degree. to 1,300.degree. C. under a reduced total pressure of about 30-70 mmHg in a reaction furnace to deposit the Si.sub.3 N.sub.4 -C series amorphous material on a surface of a substrate selected from the group consisting of graphite, silicon carbide and silicon nitride, the substrate being heated to said deposition temperature.

### Claim 2 (depends on 1)

A method as defined in claim 1, wherein the nitrogen source gas is selected from the group consisting of nitrogen hydrides and ammonium halides.

### Claim 3 (depends on 2)

A method as defined in claim 2, wherein the nitrogen source gas is NH.sub.3.

### Claim 4 (depends on 1)

A method as defined in claim 1, wherein the carbon source gas is selected from the group consisting of carbon chlorides and hydrocarbons.

### Claim 5 (depends on 4)

A method as defined in claim 4, wherein the carbon source gas is selected from the group consisting of CH.sub.4, C.sub.2 H.sub.6 and C.sub.3 H.sub.8.

### Claim 6 (depends on 1)

A method as defined in claim 1, wherein the hydrogen source gas containing the silicon source gas is introduced into the furnace.

### Claim 7 (depends on 1)

A method as defined in claim 1, wherein the atmosphere of the reaction furnace is degassed prior to initiation of deposition by evacuating to a vacuum of about 0.001 mmHg and heating the substrate at a temperature of about 700.degree. to 800.degree. C. for a few minutes.

### Claim 8 (depends on 1)

A method as defined in claim 1, wherein the atmosphere of the reaction furnace is degassed prior to initiation of deposition by evacuating to a vacuum of about 0.001 mmHg and heating the substrate at a temperature of about 700.degree. to 800.degree. C. for a few minutes, and subsequently the atmosphere of the furnace is changed to hydrogen atmosphere and the substrate is heated to a desired temperature within the defined range.

### Claim 9 (depends on 1)

A method as defined in claim 1, wherein at least one of the deposition source gases is introduced into the reaction furnace by at least one carrier gas.

### Claim 10 (depends on 9)

A method as defined in claim 9, wherein the carrier gas is selected from the group consisting of Ar, N.sub.2 and H.sub.2.

### Claim 11 (depends on 1)

A method as defined in claim 1, wherein deposition speed and deposition amount are determined by selecting pressure, temperature and types of the deposition source gases within the defined ranges.

### Claim 12 (depends on 1)

A method as defined in claim 1, wherein deposition speed and deposition amount are determined by flow rates of the deposition source gases, mixing ratio of the deposition source gases and reaction time.

### Claim 13 (depends on 1)

A method as defined in claim 1, wherein carbon content of the Si.sub.3 N.sub.4 -C series amorphous material is adjusted by regulating a flow rate of the carbon source gas.

### Claim 14 (depends on 1)

A method as defined in claim 1, wherein the carbon source gas is a hydrocarbon gas and flow rate of the hydrocarbon gas is so regulated that carbon content of the amorphous material does not exceed more than about 10% by weight.