JPH09221391A - Method for synthesizing diamond film and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To synthesize a diamond film having high adhesion to a substrate in a vapor phase. SOLUTION: When a diamond film is synthesized by a vapor phase synthesis method utilizing plasma, an evaporating source 28 disposed in a film formation chamber 10 is sputtered by charged corpuscles in plasma and the objective diamond film contg. a substance forming the evaporating source 28 is deposited on a substrate 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diamond film synthesizing method, and more particularly to a diamond film synthesizing method and apparatus for synthesizing a diamond film in a vapor phase.

[0002]

2. Description of the Related Art Diamond has a Vickers hardness of 10%.
000, which is the hardest material on earth, has a high Young's modulus, and has excellent abrasion resistance and chemical stability. Further, the thermal conductivity is 2000 W / mK, which is four times higher than that of copper, the insulating property is excellent and the dielectric constant is low. Further, it is transparent in a wide wavelength range from the infrared region to the ultraviolet region, and it becomes a semiconductor by doping impurities.

Due to such excellent properties, diamond is not only indispensable as a tool material, but also wear resistant coating, IC / LSI bonding tool, heat sink, transparent coating for optical parts, semiconductors. It is expected to be applied in a very wide range of fields such as devices. In such an applied technical field, synthesis of a diamond film is important, and various methods for synthesizing a diamond film have been proposed.

Among these diamond film synthesizing methods,
The vapor-phase synthetic diamond film synthesized by the plasma CVD method generally has poor adhesion to the substrate, which is an obstacle to various applications. For example, in applications such as bonding tools, heat sinks, and transparent coatings of optical components, which require polishing, peeling may occur during processing due to poor adhesion of the film.

In order to solve these problems, the inventors of the present application intervene a functionally graded diamond film having a graded composition between a base substrate and a diamond film to relax the thermal stress acting on the upper diamond film. Japanese Patent Application Laid-Open No. 2-224712 discloses a method of increasing the adhesion. In the method for manufacturing a diamond film described in JP-A-2-224712, while synthesizing diamond by plasma spraying, fine powder of a metal or the like forming a compound or mixture with carbon is placed on an inert gas and introduced to form a substrate. A functionally graded diamond film was formed between the substrate and the diamond film.

[0006]

However, in the above-mentioned conventional method for synthesizing a diamond film, it is difficult to control the supply amount of fine powder, and it is difficult to obtain an optimum composition for a functionally graded diamond film. Moreover, since the plasma spraying is used, the functionally graded diamond layer tends to be thick. Therefore, it is difficult to apply to a drill or the like in which it is not desirable to change the shape of the base substrate.

It is an object of the present invention to provide a diamond film synthesizing method and apparatus capable of improving the composition controllability of a graded composition layer and synthesizing a diamond film having high adhesion to an underlying substrate.

[0008]

Means for Solving the Problems The above-described object is to provide a diamond film synthesizing method for synthesizing a diamond film by a vapor phase synthesis method using plasma, in which a diamond film is formed in a deposition chamber when synthesizing the diamond film using plasma. This is achieved by a method for synthesizing a diamond film, characterized in that a provided evaporation source is sputtered by charged particles in the plasma, and a diamond film mixed with a substance forming the evaporation source is deposited on a formation surface. . By synthesizing the diamond film in this way, it is possible to easily control the mixing amount of the substance forming the vapor deposition source. Further, it is possible to reduce the thickness of the diamond film mixed with the substance forming the vapor deposition source.

In the above method of synthesizing a diamond film, a composition diamond film having a gradient composition in which the deposition source has a larger composition of a substance constituting the vapor deposition source and the surface side thereof has a larger composition of diamond is synthesized. It is desirable that the sputtering amount of the vapor deposition source be reduced as the thickness of the diamond film to be synthesized increases. By synthesizing the diamond film in this way, the composition ratio of the gradient composition diamond film in the film can be easily changed.

In the above method for synthesizing a diamond film, the vapor deposition source is sputtered by charged particles in plasma containing no diamond source gas, and a film made of a substance forming the vapor deposition source is formed on the formation surface. And the step of depositing on the film made of the substance constituting the vapor deposition source,
The sputtering amount of the evaporation source is gradually reduced so as to synthesize a gradient composition diamond film in which the deposition source has a larger composition of the material constituting the evaporation source and the surface side has a larger composition of diamond. It is desirable to have a step of gradually introducing a diamond source gas into the film chamber and a step of synthesizing a diamond film containing no substance constituting the vapor deposition source on the gradient composition diamond film. By synthesizing the diamond film in this manner, it is possible to synthesize the diamond film having excellent adhesion to the formation surface.

In the above method of synthesizing a diamond film, it is desirable to adjust the voltage applied to the vapor deposition source so as to reduce the amount of sputtering of the vapor deposition source. By doing so, the composition controllability of the graded composition diamond film can be improved. Further, the composition ratio in the depth direction can be continuously changed. A diamond film synthesizing device for synthesizing a diamond film by a vapor phase synthesis method using plasma, which is provided in a film forming chamber for synthesizing a diamond film, and uses the plasma when synthesizing the diamond film using plasma. It is also achieved by a diamond film synthesizing apparatus characterized in that it has an evaporation source that is sputtered by the method and is mixed into the diamond film. By configuring the diamond film synthesizing apparatus in this way, it is possible to easily synthesize a diamond film mixed with a predetermined substance.

The diamond film synthesizing apparatus described above preferably further comprises voltage applying means for applying a voltage to the vapor deposition source so as to control the amount of sputtering of the vapor deposition source. If the diamond film synthesizing apparatus is configured in this manner, the amount of the substance that constitutes the vapor deposition source can be easily controlled. Further, in the above diamond film synthesizing apparatus, it is desirable that the vapor deposition source is provided in the vicinity of a region from which the plasma is emitted. If the diamond film synthesizing apparatus is configured in this way, the deposition source can be efficiently sputtered by the plasma.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A diamond film synthesizing method and apparatus according to a first embodiment of the present invention will be explained with reference to FIGS. FIG. 1 is a schematic diagram for explaining the diamond film synthesizing method and apparatus according to the present embodiment, and FIG. 2 is a schematic cross-sectional view showing the diamond film synthesizing method according to the present embodiment.

First, the diamond film synthesizing apparatus according to the present embodiment will be explained with reference to FIG. The chamber 10 for synthesizing a diamond film is provided with an exhaust port 12 for reducing the pressure inside the chamber 10. Chamber 10
Further, a plasma torch 14 for generating a plasma jet of the introduced raw material gas is provided in the.

A substrate holder 16 having a water cooling mechanism (not shown) is provided in the chamber 10, and a substrate 18 for forming a film is placed on the substrate holder 16. The substrate holder 16 is connected to the manipulator 20,
The height can be adjusted. The plasma torch 14 is composed of a cathode 22 and an anode 24 for arc discharge, and a vapor deposition source 28 is attached to the tip of the plasma torch 14 via an insulator 26. Further, a raw material gas introduction pipe for introducing the raw material gas for the diamond film is connected to the plasma torch 14.

A plasma generating power source 32 is connected between the cathode 22 and the anode 24 of the plasma torch 14, and an arc 34 is generated between the cathode 22 and the anode 24 by this power source to generate a plasma jet. It is like this. A bias applying power supply 36 is connected between the anode 24 and the vapor deposition source 28 so that the vapor deposition source 28 can be sputtered by the ions in the plasma.

As described above, in the diamond film synthesizing apparatus according to the present embodiment, the vapor deposition source 28 is attached to the tip of the plasma torch 14, and a predetermined bias is applied between the vapor deposition source 28 and the anode 24. It is characterized in that it can be applied. By thus configuring the diamond film synthesizing apparatus, charged particles in the plasma jet generated by the plasma torch 14 can be made incident on the vapor deposition source 28 and sputtered.

That is, the vapor deposition source 28 just below the anode 24.
Is installed near the high-temperature thermal plasma jet, and is heated by the plasma to a high temperature. In this state, when a voltage is applied by the bias applying power source 36 to cause the ions in the plasma to enter the vapor deposition source 28, the vapor deposition source 28
Is easily sputtered by charged particles in the plasma, so that the vapor deposition source 28 can be mixed in the plasma jet.

The amount of the substance mixed in the vapor deposition source 28 can be precisely controlled by the current and voltage values applied by the bias applying power source 36. Therefore, by growing the diamond film while controlling the mixing amount of the substance of the vapor deposition source 28 by the bias applying power source 36, it is possible to deposit a so-called graded composition diamond film whose composition ratio gradually changes.

Next, the method for synthesizing the diamond film according to the present embodiment will be explained with reference to FIGS. First, the substrate 18 on which the diamond film is to be deposited is placed on the substrate holder 16, and the pressure inside the chamber 10 is reduced. Then, a predetermined gas is introduced through a source gas introduction pipe provided between the cathode 22 and the anode 24, and the pressure inside the chamber is adjusted to a predetermined value. At this time, the raw material gas for the diamond film,
For example, methane is not introduced into the chamber 10.

Subsequently, a predetermined voltage is applied by the plasma generating power source 32 to generate a DC arc discharge between the cathode 22 and the anode 24. This produces a plasma jet. The vapor deposition source 28 just below the anode 24 is
Since it is installed in the vicinity of the high-temperature thermal plasma jet, it is heated by the plasma to a high temperature. In this state, a predetermined voltage is applied by the bias applying power source 36,
Ions in the plasma are made incident on the vapor deposition source 28 and sputtered.

The sputtered vapor deposition source 28 is mixed in the plasma jet and deposited on the substrate 18. At this time, since the raw material gas for the diamond film is not introduced, the deposition film 38 of the vapor deposition source 28 is deposited on the substrate 18 (FIG. 2A). Next, the voltage of the bias applying power supply 36 is reduced at a constant rate, and at the same time, the raw material gas for the diamond film is introduced while being increased at a constant rate.

When the voltage applied by the bias applying power source 36 is reduced, the charged particles incident on the vapor deposition source 28 are reduced,
The material of the vapor deposition source 28 mixed in the plasma jet is reduced. On the other hand, when the raw material gas (CH ₄ ) for the diamond film is introduced, the synthesis of the diamond film gradually progresses. As a result, the gradient composition diamond film 40 is deposited on the substrate 18 (FIG. 2B).

Thereafter, the voltage applied by the bias applying power source 36 is set to 0 V, the amount of the raw material gas for the diamond film introduced is kept constant, and the diamond film 42 is formed on the gradient composition diamond film 40 (FIG. 2 (c)). )). By synthesizing the diamond film in this manner, it is possible to continuously synthesize the graded composition diamond film 40 in which the mixing amount is changed. By synthesizing the diamond film 42 on the gradient composition diamond film 40 thus formed, it is possible to synthesize a diamond film having high adhesion to the substrate 18.

Further, since the composition of the graded composition diamond film 40 can be accurately controlled by simply changing the voltage applied by the bias applying power source 36, the graded composition diamond film 40 can be easily thinned. Thereby, when the coating film is formed of the diamond film, the coating film can be thinned. As described above, according to this embodiment, since the vapor deposition source is attached to the tip of the plasma torch and a predetermined bias can be applied between the vapor deposition source and the anode, the amount of the substance mixed in the vapor deposition source is biased. The diamond film can be synthesized while being controlled by the power source for application.

Therefore, the graded composition diamond film can be formed with good controllability by synthesizing the diamond film while gradually reducing the amount of the material of the vapor deposition source mixed by the bias applying power source. Further, since the amount of the substance mixed in the vapor deposition source can be precisely controlled by the current and voltage values applied by the bias applying power source, the gradient composition diamond film can be easily thinned.

Next, the diamond film synthesizing method and apparatus according to the second embodiment of the present invention will be explained with reference to FIG.
The same components as those in the first embodiment are designated by the same reference numerals, and the description will be simplified or omitted. FIG. 3 is a diagram illustrating the diamond film synthesizing method and apparatus according to the present embodiment.

In the first embodiment shown in FIG. 1, the case of depositing a diamond film by the DC plasma jet CVD method has been described, but the present invention can be applied to other film forming methods using thermal plasma. . In the present embodiment, an apparatus for synthesizing a diamond film using the RF plasma jet CVD method will be shown.

The diamond film synthesizing apparatus according to the present embodiment is substantially the same as the diamond film synthesizing apparatus according to the first embodiment except for the structure of the plasma torch. That is, the plasma torch according to the present embodiment includes the RF coil 4
4 and an RF power source 46 connected to the RF coil 44, which is characterized by being constituted by an RF plasma torch 48 which generates plasma.

Next, the method for synthesizing the diamond film according to the present embodiment will be explained. First, the substrate 18 on which the diamond film is to be deposited is placed on the substrate holder 16 and the inside of the chamber 10 is depressurized, and then a predetermined gas is introduced through the source gas introduction pipe 30 to adjust the pressure inside the chamber to a predetermined value. To do. At this time, the raw material gas for the diamond film, such as methane, is not introduced into the chamber 10.

Next, the RF coil 4 is driven by the RF power source 46.
A high frequency is applied to 4 to turn the gas in the plasma torch into plasma and generate a plasma jet. Since the vapor deposition source 28 just below the plasma torch 48 is installed in the vicinity of the high-temperature thermal plasma jet, it is heated by the plasma and reaches a high temperature. In this state, a predetermined voltage is applied by the bias applying power source 36 to remove the ions in the plasma from the vapor deposition source 2
8 and sputter.

The sputtered vapor deposition source constituents are mixed in the plasma jet and deposited on the substrate 18. At this time, since the raw material gas for the diamond film is not introduced, the vapor deposition source 28 is deposited on the substrate 18. Then
The voltage of the bias applying power supply 36 is reduced at a constant rate,
At the same time, the raw material gas for the diamond film is introduced while increasing at a constant rate.

When the voltage applied by the bias applying power source 36 is reduced, the number of charged particles entering the vapor deposition source 28 is reduced,
The material of the vapor deposition source 28 mixed in the plasma jet is reduced. On the other hand, when the raw material gas for the diamond film 18 is introduced, the synthesis of the diamond film gradually progresses. As a result, a gradient composition diamond film is deposited on the substrate 18. By synthesizing the diamond film in this way, it is possible to synthesize a graded composition diamond film in which the mixing amount is continuously changed.

After that, the voltage applied by the bias applying power source 36 is set to 0 V, the amount of the raw material gas for the diamond film introduced is kept constant, and the diamond film is formed on the gradient composition diamond film. Further, by synthesizing the diamond film 42 on the gradient composition diamond film 40 thus formed, it is possible to deposit a diamond film having high adhesion to the substrate 18.

As described above, according to this embodiment, the gradient composition diamond film can be formed with good controllability also by the RF plasma jet CVD method. In the above embodiment, the vapor deposition source mixed in the plasma jet may be any kind of material as long as it is a substance having electrical conductivity such as metal or semiconductor. If a metal holder is used and an insulator is arranged on the plasma jet side of the holder so that the insulator is sputtered, the insulator can also be used as a vapor deposition source.

If a material containing the constituent element of the substrate on which the diamond film is deposited is used as the vapor deposition source, the adhesion between the diamond film and the substrate can be improved. In the above embodiment, the DC plasma jet CVD method and R
Although the method of synthesizing the diamond film by the F plasma jet CVD method has been described as an example, the method of synthesizing the diamond film may be essentially one that uses thermal plasma, and the invention can be applied to any other method. be able to.

[0037]

【Example】

Example 1 A diamond film was synthesized using the diamond film synthesizer shown in FIG. When synthesizing,
A W (tungsten) substrate was used as the substrate 18, and W was used as the vapor deposition source 28.

First, the substrate 18 was placed in the chamber 10 and the inside of the chamber 10 was depressurized. Then, a mixed gas of argon and hydrogen was introduced into the plasma torch 14 to bring the inside of the chamber 10 to a predetermined pressure. At this time, the flow rate of argon was 20 [liter / min] and the flow rate of hydrogen was 20 [liter / min]. Then, the plasma generating power source 32
Voltage is applied between the cathode 22 and the anode 24 to generate a plasma jet, and the substrate 18 is heated to 800 ° C.
Temperature. At this time, the discharge applied voltage output of the plasma generating power supply was set to 10 [kV].

After that, a voltage of about 1 [kV] is applied between the anode 24 and the vapor deposition source 28 by the bias applying power source 36 so that the charged particles in the plasma are incident on the vapor deposition source 28 and the surface thereof is Sputtered. In this way, W was mixed in the plasma jet, and W was vapor-deposited on the substrate 18. Next, the voltage applied between the anode 24 and the vapor deposition source 28 is gradually reduced, and the source gas introduction pipe 3
Starting from 0, methane gas was gradually introduced. At this time, the voltage applied between the anode 24 and the vapor deposition source 28 is set to decrease at a rate of 200 V / min, and the flow rate of methane gas is set to increase at a rate of 0.01 [liter / min] per minute. did.

By thus synthesizing the diamond film while controlling / changing the bias voltage and the flow rate of methane gas, a graded composition diamond film in which the composition changes from W to diamond was formed. Then, the anode 24
When the voltage applied between the vapor deposition source 28 and the vapor deposition source 28 became 0 V, the flow rate of methane gas was kept constant and a diamond film was synthesized on the gradient composition diamond film. The flow rate of methane gas at this time was 0.05 [liter / min].

The film thus obtained was subjected to Raman spectroscopy,
As a result of examination by X-ray diffraction and SIMS, it was observed that the surface was composed of perfect diamond and that W was continuously increased as it approached the substrate. The thickness of the mixed layer was about 3 μm. Also, sufficient adhesion to the W substrate could be obtained. Example 2 A diamond film was synthesized using the diamond film synthesizer shown in FIG. When synthesizing,
A W substrate was used as the substrate 18, and W was used as the vapor deposition source 28.

First, the substrate 18 was placed in the chamber 10 and the inside of the chamber 10 was depressurized. Then, a mixed gas of argon and hydrogen was introduced into the source gas introduction pipe 30 to bring the inside of the chamber 10 to a predetermined pressure. At this time, the flow rate of argon was 1 [liter / min] and the flow rate of hydrogen was 1 [liter / min]. Subsequently, a plasma jet of the introduced gas was generated by the RF plasma torch 48, and the substrate 18 was heated to 800 ° C.

After that, the bias applying power source 36 causes R
A predetermined voltage was applied between the F plasma torch 48 and the vapor deposition source 28 to cause charged particles in the plasma to enter the vapor deposition source 28, and the surface thereof was sputtered. In this way, W was mixed in the plasma jet to deposit W on the substrate 18. Next, the voltage applied between the RF plasma torch 48 and the vapor deposition source 28 was gradually decreased, and methane gas was started to be gradually introduced from the source gas introduction pipe 30 while being gradually increased. At this time, the flow rate of methane gas was 0.
It was set to increase at a rate of 001 [liter / min].

By thus synthesizing the diamond film while controlling / changing the bias voltage and the flow rate of methane gas, a graded composition diamond film in which the composition changes from W to diamond was formed. Subsequently, when the voltage applied between the RF plasma torch 48 and the vapor deposition source 28 became 0 V, the flow rate of methane gas was kept constant and a diamond film was synthesized on the gradient composition diamond film. The flow rate of methane gas at this time was 0.01 [liter / min].

The film thus obtained was subjected to Raman spectroscopy,
As a result of examination by X-ray diffraction and SIMS, it was observed that the surface was composed of perfect diamond and that W was continuously increased as it approached the substrate. The thickness of the mixed layer was about 1 μm. Also, sufficient adhesion to the W substrate could be obtained.

[0046]

As described above, according to the present invention, in the diamond film synthesizing method for synthesizing the diamond film by the vapor phase synthesizing method using plasma, when the diamond film synthesizing using plasma, the film formation is performed. The deposition source provided inside the chamber is sputtered by charged particles in the plasma, and the diamond film containing the substances that make up the deposition source is deposited on the surface to be formed, so the amount of substances that make up the deposition source can be easily mixed. Can be controlled. Further, it is possible to reduce the thickness of the diamond film mixed with the substance forming the vapor deposition source.

Further, in the above-mentioned method for synthesizing a diamond film, the vapor deposition source is composed so that the composition of the substance constituting the vapor deposition source is larger on the surface to be formed and the gradient composition diamond film is larger on the surface side. If the sputtering amount is reduced as the diamond film to be synthesized becomes thicker, the composition ratio of the gradient composition diamond film in the film can be easily changed.

In the above method for synthesizing a diamond film, the evaporation source is sputtered by charged particles in plasma containing no diamond source gas, and a film made of a substance constituting the evaporation source is deposited on the formation surface. In order to synthesize a graded composition diamond film on which a step and a film made of a substance constituting a vapor deposition source have a larger composition of the substance constituting the vapor deposition source on the formation surface side and a higher composition of diamond on the surface side. , A step of gradually introducing a diamond source gas into the film forming chamber while gradually reducing the sputtering amount of the vapor deposition source, and a step of synthesizing a diamond film containing no substance constituting the vapor deposition source on the gradient composition diamond film By synthesizing the diamond film by the method described above, it is possible to synthesize the diamond film having excellent adhesion to the formation surface.

In the above-mentioned method for synthesizing a diamond film, the composition controllability of the graded composition diamond film can be improved by adjusting the voltage applied to the vapor deposition source so as to reduce the amount of sputtering of the vapor deposition source. . Further, the composition ratio in the depth direction can be continuously changed. In addition, a diamond film synthesizing device for synthesizing a diamond film by a gas-phase synthesis method using plasma, which is provided in a film forming chamber for synthesizing a diamond film, and uses a plasma when synthesizing a diamond film using plasma. Since the diamond film synthesizing device is configured with the vapor deposition source that is sputtered and mixed into the diamond film, it is possible to easily synthesize the diamond film containing a predetermined substance.

Further, in the above diamond film synthesizing apparatus, by further providing a voltage applying means for applying a voltage to the vapor deposition source so as to control the sputtering amount of the vapor deposition source, the mixing amount of the substance constituting the vapor deposition source can be reduced. It can be controlled easily.
Further, in the above-mentioned diamond film synthesizing apparatus, if the vapor deposition source is provided in the vicinity of the region where the plasma is emitted, the vapor deposition source can be efficiently sputtered by the plasma.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a diamond film synthesizing method and apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a diamond film synthesizing method according to a first embodiment of the present invention.

FIG. 3 is a schematic view illustrating a diamond film synthesizing method and apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Chamber 12 ... Exhaust port 14 ... Plasma torch 16 ... Substrate holder 18 ... Substrate 20 ... Manipulator 22 ... Cathode 24 ... Anode 26 ... Insulator 28 ... Deposition source 30 ... Raw material gas introduction pipe 32 ... Plasma generation power supply 34 ... Arc 36 ... Biasing power supply 38 ... Evaporation source deposition film 40 ... Gradient composition diamond film 42 ... Diamond film 44 ... RF coil 46 ... RF power supply 48 ... RF plasma torch

Claims (7)

[Claims] 1. A method for synthesizing a diamond film by synthesizing a diamond film by a vapor phase synthesis method using plasma, wherein during the synthesis of the diamond film using plasma, an evaporation source provided in a film formation chamber is used as the plasma source. A method for synthesizing a diamond film, characterized in that the diamond film is sputtered by charged particles therein, and a diamond film mixed with a substance constituting the vapor deposition source is deposited on a formation surface. 2. The method of synthesizing a diamond film according to claim 1, wherein a gradient composition diamond film having a larger composition of a substance forming the vapor deposition source on the side of the formation surface and a larger composition of diamond on the surface side is synthesized. Thus, the method for synthesizing a diamond film, wherein the sputtering amount of the vapor deposition source is reduced as the thickness of the diamond film to be synthesized is increased. 3. The method for synthesizing a diamond film according to claim 1, wherein the vapor deposition source is sputtered by charged particles in plasma that does not contain a raw material gas of diamond, and the film made of a substance constituting the vapor deposition source is coated on the film. A step of depositing on the forming surface, and a gradient composition in which the composition of the material forming the vapor deposition source is higher toward the formation surface side and the composition of diamond is higher toward the surface side on the film made of the material forming the vapor deposition source. A step of gradually introducing a diamond source gas into the film forming chamber while gradually reducing the amount of sputtering of the vapor deposition source so as to synthesize a diamond film; and forming the vapor deposition source on the gradient composition diamond film. And a step of synthesizing a diamond film that does not contain a substance to be used. 4. The diamond film synthesizing method according to claim 2, wherein the voltage applied to the vapor deposition source is adjusted so as to reduce the amount of sputtering of the vapor deposition source. Method. 5. A diamond film synthesizing apparatus for synthesizing a diamond film by a gas phase synthesizing method using plasma, wherein the diamond film synthesizing apparatus is provided in a film forming chamber for synthesizing the diamond film and is used for synthesizing the diamond film using plasma. 1. A diamond film synthesizing apparatus, comprising: an evaporation source which is sputtered by the plasma and is mixed into the diamond film. 6. The diamond film synthesizing apparatus according to claim 5, further comprising voltage applying means for applying a voltage to the vapor deposition source so as to control a sputtering amount of the vapor deposition source. apparatus. 7. The diamond film synthesizing apparatus according to claim 5, wherein the vapor deposition source is provided in the vicinity of a region from which the plasma is emitted.