JPH0930895A - Substrate for film formation, and vapor phase synthesis of diamond and device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a thin diamond film at low cost in high productivity without being subjected to deformation or fracture. SOLUTION: In conducting a vapor phase synthesis of diamond from a gaseous carbon-contg. feedstock, the objective diamond is deposited on a substrate 10 consisting of a base material made of a material with a thermal expansion coefficient of <=10×10<-6> K<-1> and a coating layer 3 consisting of a material poorly reactive with carbon under film-forming conditions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to vapor phase synthesis of diamond. More specifically, the present invention relates to a diamond deposition substrate for use in producing a diamond film by a vapor phase synthesis method, and such a substrate. It was used,
The present invention relates to a vapor phase synthesis method and apparatus for diamond. The diamond film that can be produced in the present invention can be advantageously used as a diamond diaphragm used for a speaker of an audio device or the like.

[0002]

2. Description of the Related Art Diamond has an extremely high Young's modulus and a small specific gravity, so that the propagation speed (sound velocity) of sound waves is 18
000m / s, which is much higher than other similar materials. For this reason, the diamond thin film can exert an extremely excellent effect when used as a diaphragm for a speaker, a headphone, a microphone or the like of an audio device. In particular, the diamond film produced by the vapor phase synthesis method has an appropriate internal loss despite the extremely high sound velocity, and can be said to be the ultimate diaphragm material.

Diamond diaphragms are conventionally manufactured by the hot filament method. A typical method is “Development concept of advanced speaker system and advanced material technology, phenomenon analysis technology”, radio technology , pages 160 to 172, 1991.
As disclosed in Radio Technology Co., Ltd. in April, 2010, a substrate of silicon (Si) or the like is formed into a dome shape which is the shape of a diaphragm, and then the substrate is housed in a reaction chamber held in vacuum. Then, a mixed gas of methane and hydrogen, which is a raw material gas, is introduced, and this gas is pyrolyzed by a tungsten filament heated to 2000 ° C. or higher, thereby depositing a diamond film on the surface of the substrate. In addition,
FIG. 1 is a sectional view showing the outline of an apparatus for carrying out such a conventional hot filament method. In the figure, 11 is a diamond film, 12 is a Si substrate, 13 is a filament, 14 is a raw material gas charging port, 15 is a used raw material gas exhaust port, and 16 is a reaction chamber.

However, in the hot filament method as described above, (1) the film formation rate is slow and it takes a long time to complete the film formation. (2) the diamond film having a uniform thickness in the curved surface of the substrate. Therefore, the arrangement and support structure of the filaments becomes extremely complicated. (3) The filaments need to be replaced frequently due to elongation and deterioration (carbonization) of the filaments, and the film forming conditions are not constant. The quality of the film is not fixed. (4) In order to obtain a diaphragm, a step of removing the underlying substrate by etching is required after the diamond film is formed, and this etching also takes a long time. (5) The substrate as described above However, there is a problem in that the substrate cannot be reused, and the conventional diamond diaphragm is extremely expensive.

Then, as a result of earnest research to solve these problems, the present inventors found that Kurihara et al., “Synthesis of diamond diaphragm by DC plasma jet CVD method (Sy
nthesis of Diamond Diaphragms by DC Plasma Jet CV
D) ", Proceedings of ICNDST-4 Lectures, 755-758
As described in P., 1994, a method of manufacturing a diamond diaphragm by utilizing the difference in coefficient of thermal expansion between a substrate and a diamond film deposited thereon was found. This method uses, as a substrate, copper which does not react with carbon and has a high coefficient of thermal expansion, on which a DC plasma jet C
Since the diamond film is deposited by the VD method and the diamond film can be automatically peeled off from the substrate during cooling, there is a remarkable effect that the diamond diaphragm can be manufactured at low cost with high productivity. is there.

[0006]

However, the above-mentioned method for synthesizing a diamond diaphragm using the DC plasma jet CVD method has one problem to be solved. That is, when synthesizing a diamond diaphragm by this method, there is no problem if the thickness of the diaphragm is large, but when it is necessary to make it thinner to meet the needs, the thermal stress acting on the diamond film causes As a result of surpassing strength, the resulting diaphragm is often deformed or destroyed. In the conventional technique, it was difficult to form a thin film diamond diaphragm after various film forming conditions were changed.

Therefore, an object of the present invention is to provide a method and apparatus for vapor phase synthesis of diamond capable of producing various kinds of film-shaped diamond compacts including a diamond diaphragm in a thin film state at low cost and with good productivity. It is in. Another object of the present invention is to provide a film-forming substrate that can be advantageously used in such a diamond vapor phase synthesis method and apparatus.

[0008]

According to one aspect of the present invention, the present invention is used for producing a diamond film by a vapor phase synthesis method and has a coefficient of thermal expansion of 10 × 10 ^-6 K ^-1 or less. A substrate for film formation, comprising: a base material made of a material having: and a coating layer formed on the base material, the coating layer being made of a material having low reactivity with carbon under film forming conditions. is there.

According to another aspect of the present invention, in the vapor phase synthesis of diamond in the form of a thin film from a gaseous carbon-containing raw material, a thermal expansion coefficient of 10 × 10 ^-6 K ^-1 or less is used. Characterized in that diamond is deposited on a substrate comprising a base material made of a material having the base material and a coating layer coated on the base material and having a low reactivity with carbon under film forming conditions, It is in the vapor phase synthesis method of diamond.

Further, in another aspect of the present invention, in a diamond vapor phase synthesizing apparatus having a reaction chamber, a source material supply source and a diamond deposition substrate arranged in the reaction chamber, the substrate is 10 x 10 ^-6
It comprises a base material made of a material having a thermal expansion coefficient of K ⁻¹ or less, and a coating layer made of a material coated on the base material and having a low reactivity with carbon under film forming conditions. It is a feature of the diamond vapor phase synthesizer.

The present invention also encompasses various preferred forms and applications in connection with these substrates, methods and devices, which will be readily understood from the following detailed description.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the film formation substrate according to the present invention is used when a diamond film is manufactured by a vapor phase synthesis method. Here, as the gas phase synthesis method, one generally used in this technical field may be used as it is, or otherwise, a commonly used method may be appropriately modified and used. Good. The film-forming substrate according to the present invention has a D
C plasma jet CVD method, microwave plasma CV
It can be used particularly advantageously in a gas phase synthesis method such as the D method and the combustion flame method.

The film-forming substrate of the present invention is 10 × 10 ^-6 K
^-1 including a base material made of a material having a coefficient of thermal expansion of ^-1 or less, and a coating layer formed on the base material and made of a material having a low reactivity with carbon under film forming conditions. According to the above, an auxiliary layer may be provided as long as it does not adversely affect the intended effect. More specifically, the film formation substrate of the present invention comprises a base material 2 and a coating layer 3 coated on the surface thereof, as indicated by reference numeral 10 in FIG. 2 (A), for example. The example shown has no additional layers. Further, although the plate-shaped substrate is shown in the illustrated example, the shape of the substrate can be arbitrarily changed according to the desired shape of the diamond film. For example, if the intended diamond compact is a diamond diaphragm, the shape of the substrate can be a dome shape.

The base material of the substrate of the present invention is 10 × 10.^-6 K
^-1It must consist of a material with the following coefficient of thermal expansion:
is there. This means that the coefficient of thermal expansion of the base material is at most 10 x
10 ^-6 K^-1By, that is, the conventional group
Base material that has a smaller coefficient of thermal expansion than the material
Continued diamond film formation by adoption
The stress generated when the board is cooled is kept to a minimum level.
The thermal stress, which has been a problem with conventional technology.
There is a great purpose in preventing shape or destruction.

By the way, if only the base material as described above is used for forming the film formation substrate, it is not possible to achieve automatic peeling of the formed diamond film from the substrate after the film formation. However, the automatic peeling of the diamond film from the substrate can be solved by entrusting its function to the coating layer provided on the base material. That is, since the coating layer material is made of a material having a low reactivity with carbon under the film forming conditions, the adhesion between the substrate and the diamond film deposited thereabove is small, and therefore the diamond from the substrate is completed after the film formation is completed. It is possible to peel off the film easily. Further, in the present invention, in selecting the base material and the coating layer material, it is possible to further enhance the effect that can be obtained in the present invention by taking into consideration that the actions of both materials are advantageously extracted. You can Therefore, when the film-forming substrate of the present invention is used for the synthesis of diamond using the vapor phase synthesis method, the substrate and the diamond film can be easily separated without applying stress to the film, so that the film thickness is small. Even a molded body having a low mechanical strength can be easily produced without deformation or destruction of the film, and the molded body can be easily separated from the substrate.

In the practice of the present invention, the substrate of the film-forming substrate
As the material of 10 × 10^-6 K ^-1The following coefficient of thermal expansion
Appropriately selected from materials having
can do. Suitable substrate materials are listed below.
Iridium, though not limited to
Chromium, tungsten, tantalum, cobalt, titanium,
A member selected from the group consisting of molybdenum and its alloys
A metal material containing silicon as a main component, silicon, germanium, boron,
One selected from the group consisting of vanadium and its compounds
Of non-metallic materials whose main component is, and generally super hard materials
Known as tungsten carbide, molybdenum carbide
Made of titanium, titanium carbide, silicon carbide and their composite materials, etc.
Carbide-based ceramics whose main component is a member selected from the group
Including materials. The thickness of the substrate depends on the shape of the substrate, the substrate and
Seed material for each coating layer used in combination
Widely varied depending on the type, desired effect, and other factors.
Although it can be changed, if a flat board is taken as an example,
Is about 500 μm or more.

The coating layer applied on the substrate is preferably
It can be formed of a metal material which is mainly composed of a member selected from the group consisting of gold, platinum, copper and alloys thereof and which is difficult to react with carbon. However, if there is another material that is less likely to react with carbon and that the material can meet the requirements required for the coating layer of the present invention, then that material may be used alone or as described above. You may use it with the aid of various materials. The film thickness of the coating layer is widely changed depending on the shape of the substrate, the type of each material of the coating layer and the substrate supporting the same, the desired effect, and other factors, as in the case of the above-mentioned substrate. Although it is possible,
Taking a flat substrate as an example, it is generally advantageous that it is about 0.1 to 20 .mu.m or even more.

According to the present invention, a base material made of a material having a coefficient of thermal expansion of 10 × 10 ^-6 K ^-1 or less is used in the vapor phase synthesis of diamond in the form of a thin film from a gaseous carbon-containing raw material. And a method for vapor phase synthesis of diamond, characterized in that diamond is deposited on a substrate including a coating layer coated on the substrate and made of a material having low reactivity with carbon under film forming conditions. Provided. Here, the substrate on which diamond is to be deposited is the film-forming substrate as described above.

The principle of the vapor phase synthesis method of diamond according to the present invention will be described below with reference to FIG. First, as shown in FIG. 2A and described in detail above, the substrate 10 including the base material 2 and the coating layer 3 is prepared. The substrate 10 can be formed by applying the coating layer 3 using various film forming methods. Suitable film forming methods for the coating layer 3 include, for example, a sputtering method, a laser ablation method, Examples thereof include an ion plating method and an ion assisted deposition method.

Then, a diamond film 1 is deposited on the surface of the formed substrate 10 by using an arbitrary vapor phase synthesis method as shown in FIG. 2 (B). Here, the gaseous carbon-containing raw material that is the source for forming the diamond film is not particularly limited as long as it can lead to the desired diamond film in the practice of the present invention, and includes various substances. For example, to give just one example, a suitable carbon-containing source material is a hydrocarbon gas such as methane or acetylene.
It is used as a mixed gas in combination with plasma gas such as hydrogen gas or oxygen gas. The mixing ratio of each gas can be arbitrarily changed according to the conditions of vapor phase synthesis, the desired characteristics of the diamond film, and other factors. Regarding the vapor phase synthesis method used here, if the intention is to use the DC plasma jet CVD method, see the proceedings of Kurihara et al. Cited above and JP-A-64-33096. The techniques described can be utilized. The DC plasma jet CVD method will be described in detail below with reference to the drawings. Also, as mentioned above, microwave plasma CVD method, combustion flame method and other methods using thermal plasma are also available.
It can be used as needed.

After the film formation is completed, as shown in FIG.
The diamond film 1 is peeled off from the substrate 10. This peeling work can be easily performed by using an appropriate peeling jig (not shown) because the adhesion of the diamond film 1 to the coating layer 3 is not large, and at that time, the film is broken or cracked. Does not occur. Further, according to the present invention, there is also provided an apparatus for carrying out the above-described vapor phase synthesis method. The diamond vapor phase synthesizing apparatus according to the present invention requires at least a reaction chamber, a source material source arranged in the reaction chamber, and a diamond deposition substrate according to the present invention. In addition to the elements, it can optionally have the components necessary to perform each vapor phase synthesis.

The reaction chamber can preferably be composed of a chamber capable of depressurizing, and can be equipped with means for easily carrying in and out the substrate and the like. Also,
The morphology of this reaction chamber can be optimized depending on the method of gas phase synthesis used. For example, D
In the case of the C plasma jet CVD method, it is possible to use a device developed by Fujitsu Automation Co., Ltd. and used as mentioned in the previous lectures by Kurihara et al.

Further, the source material supply source can be arranged in the reaction chamber in combination with various supply means.
For example, in the case of the DC plasma jet CVD method, a suitable carbon-containing source material such as methane gas and argon gas,
A mixed gas with a plasma gas such as hydrogen gas can be used as a source material supply source, which can be placed in the reaction chamber in combination with a supply means such as a plasma torch.

Further, the diamond deposition substrate arranged in the reaction chamber is that of the present invention described above. This substrate can be placed in the reaction chamber supported by a suitable substrate holder, as is commonly done in vapor phase synthesis methods. It is recommended that the substrate holder be cooled by water cooling means or the like for the purpose of preventing the temperature of the substrate supported on it from rising excessively, and for other purposes.

The diamond vapor phase synthesis apparatus according to the present invention is, in a preferred embodiment, a DC plasma jet C.
According to the VD method, a DC plasma torch and a diamond deposition substrate facing the DC plasma torch are provided in a decompression chamber as a reaction chamber, and the substrate has a shape suitable for the desired shape of the diamond compact. It is in a diamond vapor phase synthesizer. Here, the decompression chamber is also equipped with a source gas supply system for supplying a source gas to the plasma torch and a gas discharge system from the decompression chamber.

More specifically, the vapor phase synthesis apparatus of the above-described mode is as schematically shown in FIG. A DC plasma torch 6 attached to the upper part of the decompression chamber 20 is connected to an argon gas from a gas charging port 4 communicating with the DC plasma torch 6.
A raw material gas consisting of three kinds of gases, methane and hydrogen, is introduced and turned into plasma by arc discharge. On the other hand, the substrate 10 on which the diamond film is to be deposited is
It is supported by a substrate holder 8 having a built-in water cooling means (not shown), and can be moved up and down by a manipulator 9. The substrate 10 is composed of a base material 2 and a coating layer 3 above the base material 2 as shown in the drawing. Further, since the purpose is to make a diamond diaphragm here, the substrate 10 is formed according to the shape of the diaphragm. The form is adopted. During the vapor phase synthesis, the plasma torch 6 irradiates the surface of the substrate 10 with the plasma jet 7, and the substrate 1
Diamond (not shown) is gradually deposited on the 0 surface. The used raw material gas is exhausted from the exhaust port 5 to the chamber 20.
It is discharged outside. By using the illustrated vapor phase synthesizing apparatus, therefore, the diamond diaphragm can be produced at a significantly low cost, in a short time, and in a small number of steps with high productivity as compared with the case of using the conventional apparatus. Note that Japanese Patent Application Laid-Open No. 64-33096 also discloses a method of synthesizing a diamond film, which will be a diaphragm of a speaker or the like, by the DC plasma jet CVD method in relation to the DC plasma jet CVD method illustrated and described here. Please refer to them as well.

Regarding the DC plasma jet CVD method,
It will be further summarized. In this method, in short, high temperature thermal plasma generated by direct current arc discharge is ejected from a torch nozzle as a plasma jet, and this plasma jet is irradiated toward a substrate to obtain several tens of tens.
It is a high-speed diamond synthesizing method that can obtain a film formation rate on the order of 0 μm / h. By performing diamond film formation by this method, (1) film formation time can be reduced to several tenths to several hundredths of that of the hot filament method.
(2) Since this method is a method in which the plasma jet ejected from the plasma torch is blown onto the substrate, it does not require complicated operations such as filament adjustment and reattachment unlike the hot filament method, and a large amount of continuous (3) The substrate can be formed into a convex shape or a concave shape according to the desired shape of the formed body, and the concave shape can smooth the acoustic emission image. Alternatively, by using a convex shape, it is possible to obtain an effect that the voice coil bobbin can be integrally combined.

In the diamond synthesis by the DC plasma jet CVD method, argon is usually used as a plasma gas,
Hydrogen is used, and hydrocarbon gas such as methane is supplied as a carbon source in an amount of about several percent of the total gas amount.However, since the conversion efficiency of hydrocarbon gas to diamond is several percent or less, the gas Is extremely inefficient to use.
In order to solve this problem, it is recommended that the raw material gas supplied to the chamber is reused by circulating a part or the whole of the raw material gas instead of exhausting it all after its use. If the raw material gas is reused, it is sufficient to supply only the carbon content consumed in the diamond synthesis, so that the consumed gas amount is significantly reduced. Although the composition of the hydrocarbon in the gas exhausted from the chamber is different from the composition supplied to the torch, it is considered that the DC plasma jet CVD method has a small effect due to the difference in the type of the hydrocarbon gas.

In diamond vapor phase synthesis using a DC plasma torch, typically, an inert gas + hydrogen is supplied to the plasma torch to generate plasma, and a carbon compound is supplied to the plasma flame from outside the torch. Diamond is synthesized by using a gas, but when recirculating the gas, inert gas, hydrogen, and carbon compounds (unreacted products, reaction products) are mixed. Generally, this should be separated. Instead, it will be supplied to the plasma torch in the form of a mixed gas. Since the composition of this recirculated gas is slightly different from the resuitable supply gas composition, the composition of the recirculated gas is accurately analyzed using gas chromatography, etc., and the gas supplemented with insufficient hydrogen and carbon compounds is used as the source gas. Supply to a plasma torch is desirable.

The diamond vapor phase synthesizer according to the present invention is, in another preferred embodiment thereof, a diamond vapor phase synthesizer by a microwave plasma CVD method. This vapor phase synthesizer is as schematically shown in FIG. That is, the vapor phase synthesizer is set to the microwave plasma C.
The chamber 30 and the microwave waveguide 31 which can be decompressed are combined and configured as is usually performed in the apparatus of the VD method. In the chamber 30, as shown in the figure, the substrate 10 including the base material 2 and the coating layer 3 is supported by the substrate holder 38 and arranged. A raw material gas in which hydrogen and methane are mixed is supplied from above the substrate 10, while the microwave 33 for excitation is introduced from the waveguide 31. By operating the attached plunger 32 and applying a standing wave of a microwave having a frequency of 2450 MHz to the periphery of the substrate, the raw material gas is turned into plasma. The raw material gas turned into plasma gradually becomes the substrate 10.
Diamond film (not shown) deposited on the surface of the
Is formed.

The diamond vapor phase synthesizer according to the present invention is, in another preferred embodiment thereof, a diamond vapor phase synthesizer by a combustion flame method. This vapor phase synthesizer can be constructed according to a conventional method and is as schematically shown in FIG. That is, the substrate 10 is attached to the water-cooled substrate holder 48 arranged in the chamber 40 as shown. Further, below the substrate 10, a burner is provided so that the combustion flame 47 of the source gas (mixture of oxygen and acetylene) supplied from the charging port 44 is effectively blown to the surface of the substrate during the gas phase synthesis process. 46 is placed. Diamond (not shown) is gradually deposited on the surface of the substrate 10.

[0032]

The present invention will now be described with particular reference to making a diamond diaphragm. It should be understood that the present invention is not limited to the examples described below. Example 1 Preparation of diamond diaphragm by DC plasma jet CVD method Using the vapor phase synthesizing apparatus shown in FIG. 3, a diamond diaphragm was prepared by the following procedure. A film-forming substrate comprising a silicon (Si) base material and a copper (Cu) coating layer is prepared,
It was housed in the chamber of the vapor phase synthesizer using a substrate holder. The thickness of the copper coating layer is 0.02 μm in order to evaluate its effect on the thickness of the obtained diamond film.
, 0.2 μm and 2 μm were applied. Prior to performing the gas phase synthesis, the pressure in the chamber was reduced to 30 Torr. Then, 30 L / min of argon gas and 30 L of hydrogen gas were put into the plasma torch in the decompression chamber.
/ Min and methane gas at a concentration of 0.5% were introduced, respectively, and plasma was generated by arc discharge. The discharge output was 10 kW. A thin film of diamond was deposited on the surface of the substrate kept at a temperature of 800 ° C. The obtained film formation results are shown in Table 1 below. Table 1 Diamond film Thickness of copper coating layer (μm) Thickness (μm) 0.02 0.2 2 0.5 × × × 2.0 × ○ ○ 5.0 × ○ ○ 30 × ○ ○ From the results, it is understood that when the diamond diaphragm is prepared according to the present invention, a dome-shaped diamond compact is obtained when the thickness of the copper coating layer is 0.2 μm or more. In addition, in these molded products, deformation, cracks, etc. could not be recognized. Example 2 Preparation of Diamond Vibration Plate by Microwave Plasma CVD Method Using the vapor phase synthesizing apparatus shown in FIG. 4, a diamond vibration plate was prepared by the following procedure. Tungsten (W)
A film-forming substrate including a base material and a platinum (Pt) coating layer was prepared and housed in a chamber of a vapor phase synthesizer using a substrate holder. The thickness of the platinum coating layer was 0.1% in order to evaluate its influence on the thickness of the obtained diamond film.
Three types of μm, 2 μm and 5 μm were applied. Prior to performing the gas phase synthesis, the pressure in the chamber was reduced to 30 Torr. Next, 100 SC of hydrogen gas was introduced into the chamber.
CM and methane gas were introduced at a concentration of 2%, respectively, while microwaves were introduced from the waveguide at an output of 800W. The raw material gas was turned into plasma by operating the attached plunger. A thin film of diamond was deposited on the surface of the substrate kept at a temperature of 800 ° C. The obtained film formation results are shown in Table 2 below.

Table 2 Diamond film Thickness of platinum coating layer (μm) Film thickness (μm) 0.1 2 5 0.5 × × × 2.0 ○ ○ ○ 5.0 ○ ○ ○ 30 ○ ○ ○ Above From the results, it can be seen that when the diamond diaphragm is produced according to the present invention, a dome-shaped diamond compact can be obtained when the platinum coating layer has a thickness of 0.1 μm or more. In addition, in these molded products, deformation, cracks, etc. could not be recognized. Example 3 Preparation of diamond diaphragm by DC plasma jet CVD method The procedure described in Example 1 above was repeated. However, in the case of this example,
As the film-forming substrate, a film-forming substrate comprising a base material of Fe—Ni steel (50:50) and a gold (Au) coating layer was used, and the film thickness of the gold coating layer was set to that of the obtained diamond film. To evaluate its effect on film thickness, 0.2 μm, 0.8
Changed to μm and 5 μm. The obtained film formation results are shown in Table 3 below. Table 3 Diamond film Thickness of gold coating layer (μm) Thickness (μm) 0.2 0.8 5 0.5 × × × 2.0 ○ ○ ○ 5.0 ○ ○ ○ 30 ○ ○ ○ From the results, it is understood that when the diamond diaphragm is produced according to the present invention, a dome-shaped diamond compact can be obtained when the thickness of the gold coating layer is 0.2 μm or more. In addition, in these molded products, deformation, cracks, etc. could not be recognized. Example 4 Preparation of Diamond Vibrating Plate by DC Plasma Jet CVD Method The procedure described in Example 1 above was repeated. However, in the case of this example,
As a substrate for film formation, a silicon carbide (SiC) base material and Cu
In order to evaluate the influence of the film thickness of the Cu-Pt alloy coating layer on the thickness of the obtained diamond film, a film-forming substrate comprising a -Pt alloy coating layer is used.
Changed to μm, 1 μm and 5 μm. The obtained film formation results are shown in Table 4 below. Table 4 diamond film Cu-Pt coating layer having a thickness ([mu] m) film thickness (μm) 0.2 1 5 0.5 × × × 2.0 ○ ○ ○ 5.0 ○ ○ ○ 30 ○ ○ ○ above From the results, when the diamond diaphragm is prepared according to the present invention, the film thickness of the Cu—Pt coating layer is 0.2 μm.
It is understood that a dome-shaped diamond compact can be obtained when the above is performed. In addition, in these molded products, deformation, cracks, etc. could not be recognized.

[0034]

According to the present invention, a thin diamond film, especially a diamond diaphragm, which could not be manufactured by the conventional method, can be manufactured at low cost and with high productivity without suffering film deformation or destruction. It can be manufactured. According to the present invention, therefore, the applicable range of diamond film applied products can be dramatically expanded.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a conventional apparatus for forming a diamond film by a hot filament method.

FIG. 2 is a schematic cross-sectional view showing an example of a film formation substrate according to the present invention and a diamond film formation using the same in order.

FIG. 3 is a schematic sectional view showing a preferred example of a diamond film forming apparatus by a DC plasma jet CVD method according to the present invention.

FIG. 4 is a schematic sectional view showing a preferred example of a diamond film forming apparatus by a microwave plasma CVD method according to the present invention.

FIG. 5 is a schematic sectional view showing a preferred example of a diamond film forming apparatus by a combustion flame method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Diamond film 2 ... Substrate 3 ... Coating layer 6 ... Plasma torch 7 ... Plasma jet 8 ... Substrate holder 10 ... Film-forming substrate 20 ... Reaction chamber (chamber)

Claims (17)

[Claims] 1. A base material made of a material having a coefficient of thermal expansion of 10 × 10 ⁻⁶ K ⁻¹ or less, which is used when a diamond film is produced by a vapor phase synthesis method, and a base material on the base material. A film-forming substrate comprising a coated coating layer made of a material having low reactivity with carbon under film-forming conditions. 2. The material of the base material is a metal material containing as a main component a member selected from the group consisting of iridium, chromium, tungsten, tantalum, cobalt, titanium, molybdenum and alloys thereof. The film-forming substrate according to claim 1. 3. The non-metallic material having a member selected from the group consisting of silicon, germanium, boron, vanadium and compounds thereof as a main component, as the material of the base material, according to claim 1. The film-forming substrate described. 4. The material of the base material is tungsten carbide,
The film-forming substrate according to claim 1, wherein the film-forming substrate is a carbide ceramic material containing a member selected from the group consisting of molybdenum carbide, titanium carbide, silicon carbide and a composite material thereof as a main component. 5. The method according to claim 1, wherein the material of the coating layer is a metal material whose main component is one member selected from the group consisting of gold, platinum, copper and alloys thereof. 2. The film formation substrate according to item 1. 6. 10 × 10 10 in vapor phase synthesis of diamond in the form of a thin film from a gaseous carbon-containing raw material.
^On a substrate including a base material made of a material having a thermal expansion coefficient of ^-6 K ^-1 or less, and a coating layer formed on the base material and made of a material having low reactivity with carbon under film forming conditions A method for vapor-phase synthesis of diamond, which comprises depositing diamond on a substrate. 7. The material of the base material is a metal material containing as a main component a member selected from the group consisting of iridium, chromium, tungsten, tantalum, cobalt, titanium, molybdenum and alloys thereof. The gas phase synthesis method according to claim 6. 8. The non-metallic material containing a member selected from the group consisting of silicon, germanium, boron, vanadium, and compounds thereof as a main component, as the material of the base material. The described gas phase synthesis method. 9. The material of the base material is tungsten carbide,
The vapor phase synthesis method according to claim 6, which is a carbide-based ceramic material containing a member selected from the group consisting of molybdenum carbide, titanium carbide, silicon carbide, and composite materials thereof as a main component. 10. The material of the coating layer is a metal material containing, as a main component, one member selected from the group consisting of gold, platinum, copper and alloys thereof. The gas phase synthesis method according to Item 1. 11. The method according to claim 6, wherein the vapor phase synthesis of the diamond film is performed based on a DC plasma jet CVD method, a microwave plasma CVD method or a combustion flame method. The described gas phase synthesis method. 12. A vapor phase diamond synthesizing apparatus comprising a reaction chamber, a source material supply source and a diamond deposition substrate arranged in the reaction chamber, wherein the substrate is 10
A base material made of a material having a coefficient of thermal expansion of × 10 ^-6 K ^-1 or less, and a coating layer made of a material coated on the base material and having a low reactivity with carbon under film forming conditions. A vapor-phase synthesis apparatus for diamond, characterized in that 13. The material of the base material is a metal material containing as a main component a member selected from the group consisting of iridium, chromium, tungsten, tantalum, cobalt, titanium, molybdenum and alloys thereof. Claim 12
The gas phase synthesizer according to. 14. The material according to claim 12, wherein the material of the base material is a non-metallic material whose main component is one member selected from the group consisting of silicon, germanium, boron, vanadium and compounds thereof. The described vapor phase synthesizer. 15. The material of the base material is a carbide-based ceramic material containing, as a main component, one member selected from the group consisting of tungsten carbide, molybdenum carbide, titanium carbide, silicon carbide and composite materials thereof. Claim 1
2. The vapor phase synthesizer according to item 2. 16. The material of the coating layer is a metal material containing, as a main component, a member selected from the group consisting of gold, platinum, copper and alloys thereof. The vapor phase synthesis apparatus according to Item 1. 17. The vapor phase synthesis of a diamond film is performed based on a DC plasma jet CVD method, a microwave plasma CVD method or a combustion flame method, according to any one of claims 12 to 16. The described vapor phase synthesizer.