JP3047488B2 - Apparatus and method for producing diamond film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, various methods have been proposed as low-pressure vapor-phase synthesis methods for diamond films. First, there is a hot filament CVD method. In this method, a tungsten filament is provided directly above a substrate heated to 800 to 1000 ° C., the filament is heated to 2000 ° C. or higher, hydrogen and a hydrocarbon gas (eg, CH ₄ ) are blown through the filament to the substrate, and diamond is placed on the substrate. This is a method of growing a film.

[0003] Second, a microwave plasma CVD method is known. This is a method in which plasma is generated in a mixed gas gas of hydrogen and hydrocarbon gas by a microwave of several hundred watts, and diamond is grown on a substrate placed in the plasma.
The temperature is about 00 to 900 ° C.

[0004] In these two kinds of synthesis methods, atomic hydrogen promotes the decomposition of CH ₄ and further acts to selectively etch synthetic substances other than diamond such as amorphous carbon. Plays an important role. However, the hot filament CVD method in which the filament is heated to a high temperature has many problems that the filament is broken, and is not practical. Further, considering the melting point of tungsten, the temperature of the filament is about 2000 ° C., and if it is higher than that, there is a problem that disconnection is caused and sufficient decomposition of the raw material gas cannot be performed. In addition, in the synthesis method using microwave plasma, it is difficult to apply the method to a large-area sample because the size of the plasma chamber is restricted.
In particular, there is a problem that decomposition of hydrogen becomes insufficient.

A third method is a synthesis method using an ion beam. This is intended to grow a diamond film by applying a carbon ion beam to a substrate. However, there is a problem that the diamond contains a large amount of impurities such as amorphous.

Accordingly, for example, Japanese Patent Application Laid-Open No. 63-176399
As a method that can effectively utilize a source gas as proposed in Japanese Patent Application Laid-Open No. H10-201097 or Japanese Unexamined Patent Application Publication No. HEI 1-220107, gas plasma is generated by causing an arc discharge in an opposed electrode and passing the source gas through the arc discharge. A synthesis method is known in which this gas plasma is sprayed onto a substrate as a plasma jet gas by means of a throttle to deposit and form diamond on the substrate.

[0007]

However, this synthesis method also has a problem that it is insufficient in terms of gas decomposition (dissociation) near the substrate to which the source gas is blown.

That is, although the gas decomposition rate is significantly improved by using arc discharge, it is only in the vicinity of the arc discharge generating portion, and remarkably due to recombination reaction or the like in the vicinity of the substrate where plasma is sprayed onto the substrate as a plasma jet. Is declining. FIG. 3 shows a characteristic diagram in which the amount of hydrogen radicals (decomposed hydrogen) from the nozzle portion (plasma ejection port) of the plasma jet to the substrate is represented by the spectrum intensity of the hydrogen Balmer series emission spectrum Hβ. As is clear from FIG. 3, the gas decomposition rate decreases remarkably as the distance from the plasma outlet increases, that is, near the substrate.

Here, it is conceivable to perform the synthesis at a position where the gas decomposition rate is high by bringing the substrate closer to the plasma jetting port. However, this will increase the substrate temperature, and will increase the impurity carbon such as graphite other than diamond. There is a problem that generation is rapidly increased. This is because a substrate temperature of 600 to 1100 ° C. when diamond is synthesized is suitable, and 800 to 1000 ° C. is optimum for high purity synthesis.

Therefore, in order to synthesize diamond with higher efficiency, it is necessary to increase the gas decomposition rate near the substrate without increasing the substrate temperature. The present invention has been made in view of the above circumstances, and has as its object to provide a diamond film manufacturing apparatus and a manufacturing method capable of synthesizing a high-quality diamond film with high efficiency.

[0011]

In order to achieve the above object, a diamond film manufacturing apparatus according to the present invention has the following configuration. That is, a vacuum container maintained at a predetermined degree of vacuum, a positive electrode and a negative electrode disposed in the vacuum container so as to face each other, and electrically connected to the positive electrode and the negative electrode, and a space between the positive electrode and the negative electrode. An arc discharge power supply for supplying a predetermined power to cause arc discharge, and a source gas containing at least hydrogen and carbon for the arc discharge to generate a gas plasma, and the gas plasma is disposed downstream thereof. Gas supply means for blowing onto the substrate, a positive electrode for plasma current arranged at a predetermined distance from the substrate between a region where the gas plasma is generated and the substrate, and decomposition of the source gas. A plasma current power supply for flowing a predetermined current from the plasma current positive electrode into the gas plasma to promote the plasma current positive electrode; The predetermined distance to be separated from the substrate is set in advance to a value that prevents the temperature of the substrate from rising due to the current flowing in the gas plasma by the plasma current power supply. The predetermined current passed through the gas plasma by the plasma current power supply is set to a value of about 20 A or more in advance.

Further, in the method for producing a diamond film according to the present invention, a gas plasma is generated by flowing a source gas containing at least hydrogen and carbon into an arc discharge.
In a method of depositing and forming a diamond film on a substrate by spraying the gas plasma on a substrate disposed downstream thereof, a predetermined distance from the substrate is defined between a region where the gas plasma is generated and the substrate. A positive electrode for plasma current is arranged at a distance, and approximately 2 mm is provided between the positive electrode for plasma current and the side of the region where the gas plasma is generated.
The present invention is characterized in that an electric field that causes the plasma current positive electrode to have a high potential is applied in order to flow a current of 0 A or more.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 1 is a sectional structural view of a manufacturing apparatus according to a first embodiment of the present invention.

In FIG. 1, a plasma jet gun 1
A ring-shaped insulator 40 made of boron nitride, a ring-shaped positive electrode 31 made of copper, a substrate 2 and a substrate support 3 made of copper are vacuum containers maintained at a predetermined pressure within a range of 5 Torr to 5 atm. 5.

The plasma jet gun 1 has an electrode 7 made of copper from the flange 7b side with a rod-shaped electrode 7 made of tungsten formed at a tip 7a having an acute angle at one end and a flange 7b at the other end. A cooling section 8, a gas introduction section 9 made of Teflon, and a cylindrical electrode 10 made of copper are provided. The electrode cooling unit 8 and the cylindrical electrode 10 are provided with hollow portions 108 and 110 which are hollow. Then, the cooling water supplied from the cooling water pipe 14 connected to the cylindrical electrode 10 flows out of the hollow portion 110 of the cylindrical electrode 10 to the cooling water pipe 14a. Similarly, the cooling water pipe 1 connected to the electrode cooling unit 8
5 is supplied to the hollow portion 108 of the electrode cooling portion 8.
Water pipe 1 supplied to the electrode cooling unit 8
It is discharged from 5a. The cooling water prevents wear of both electrodes due to heat of arc discharge generated between the rod-shaped electrode 7 and the cylindrical electrode 10. The gas introduction section 9 is provided with a raw material gas introduction pipe 16. Further, an opening for sending the gas supplied from the gas introduction pipe 16 to the distal end portion 7 a of the rod-shaped electrode 7 is provided in the gas introduction section 9. It is configured on one end side.

Further, the rod-shaped electrode 7 and the cylindrical electrode 10
The rod electrode 7 and the cylindrical electrode 10 are connected to an arc discharge power source 17 in order to cause an arc discharge between the electrodes. The arc discharge power supply 17 has a sharply formed tip portion 7 for effectively generating arc discharge.
The rod-shaped electrode 7 having a is connected to a negative potential. Further, on the surface of the cylindrical electrode 10 opposite to the gas introduction portion 9, there is provided a plasma jet port 18 for narrowing the gas plasma to be a plasma jet gas. Further, a ring-shaped insulator 40 and a ring-shaped positive electrode 31 which are connected to the plasma outlet 18 and constitute a plasma passage are provided. Further, a carbon source gas inlet 19 is provided in the plasma outlet 18.

The ring-shaped positive electrode 31 is arranged at or near the position where the plasma jet gas has the maximum diameter C downstream of the plasma jet port 18, and the arrangement setting is given by the length of the ring-shaped insulator 40. ing. The ring inner diameter of each of the ring-shaped insulator 40 made of boron nitride and the ring-shaped positive electrode 31 made of copper is set to be larger than the diameter of the plasma jet port 18, and the ring inner diameter A of the ring-shaped positive electrode 31 is particularly large. Plasma spout 1
The inner diameter B is determined so as to satisfy A ≦ 5B with respect to the inner diameter B as described later. A power supply 2 for plasma current is provided between the rod-shaped electrode 7 and the ring-shaped positive electrode 31.
1 is electrically connected. This means that an electric field is applied between the rod-shaped electrode 7 and the ring-shaped positive electrode 31,
This is to allow a current equal to or greater than a predetermined value to flow through the plasma to the rod-shaped electrode 7 through the plasma.

The ring-shaped positive electrode 31 is provided with a hollow portion 112 which is hollow. Cooling water is supplied to the hollow portion 112 from a cooling water introduction pipe 32 so that the cooling water pipe 32
is discharged to a. This cooling water allows the ring-shaped positive electrode 3
1 is cooled, the heating of the ring-shaped positive electrode 31 by the current flowing between the rod-shaped electrode 7 and the ring-shaped positive electrode 31 is suppressed, and the wear of the ring-shaped positive electrode 31 due to the heating is prevented.

A substrate support 3 is set downstream of the plasma ejection port 18 via the ring-shaped insulator 40 and the ring-shaped positive electrode 31, and the substrate 2 is disposed on the substrate support 3. . The substrate support 3 is hollow so that cooling water is supplied from a cooling water pipe 20 and is discharged from a cooling water pipe 20a to maintain the substrate at a predetermined temperature (about 800 ° C. in this embodiment). This is because the gas temperature of the plasma jet ejected from the plasma ejection port 18 reaches several thousands to tens of thousands of degrees, so that the substrate 2 is cooled in order to keep the substrate temperature at 600 to 1100 ° C., which is a diamond synthesis region. It is necessary to do it. The substrate support 3 is grounded, and the potential of the substrate 2 is set to the ground potential.

The distance between the ring-shaped positive electrode 31 and the substrate 2 is 10 to 100 mm, and the distance between the region where the gas plasma is generated and the ring-shaped positive electrode 31 is 5 to 100 m.
m, it is possible to synthesize diamond. In this embodiment, the distance between the plasma ejection port 18 and the substrate 2 is set to 40 mm, and the ring-shaped positive electrode 31 is used to deposit high-purity diamond. It is installed on a concentric axis with the plasma jet port 18 at a distance of 2 mm above 20 mm.

Next, a method of synthesizing the diamond film of the present embodiment will be described. First, after the inside of the vacuum vessel 5 is evacuated, argon as a Group 0 gas having a high degree of ionization is introduced into the plasma jet gun 1 from the gas introduction pipe 16 and the pressure inside the vacuum vessel 5 is set to 40 Torr. . Thereafter, an arc discharge is generated between the rod-shaped electrode 7 (negative electrode) and the cylindrical electrode 10 (positive electrode) by the arc discharge power supply 17. In order to generate an arc discharge, a high frequency may be superimposed between the rod-shaped electrode 7 and the cylindrical electrode 10 or a spark discharge may be generated by an igniter or the like, and then the arc discharge may be started. In this embodiment, the arc discharge is performed under the conditions of a voltage of 40 V and a current of 60 A.

When the discharge is stabilized, a mixed gas of 50 vol% of argon and 50 vol% of H _{2 is} supplied as a plasma source gas at a flow rate of 12 liters per minute from the gas introduction pipe 16 to the gas discharge to form a gas plasma. Is passed through the restriction of the plasma jet port 18 to form a plasma jet. From the carbon source gas inlet 19, methane gas 240 cc / min and hydrogen gas 60 cc / min
Is introduced. Here, the hydrocarbon gas as a carbon source gas represented by methane gas may be introduced from the gas introduction pipe 16, but since the tungsten electrode rod is carbonized, the discharge may not be stable for a long time.
It is desirable to provide a gas inlet downstream of the discharge part and to introduce the hydrocarbon gas therefrom. Then, the methane gas introduced from the carbon source gas inlet 19 is blown onto the plasma jet of the above-mentioned plasma source gas to be a plasma jet gas. At this time, in the apparatus of the present embodiment, the maximum diameter C of the plasma jet gas was approximately 20 mm. In addition,
Here, evacuation is appropriately performed so that the pressure in the vacuum vessel 5 is maintained at 40 Torr.

Here, the rod-shaped electrode 7 and the ring-shaped positive electrode 31
Between them, an electric field is applied by a plasma current power supply 21 which is a DC power supply. In this embodiment, the voltage is 60
V is applied, and a current of 20 A or more, for example, a current value of 40 A flows in the plasma. The substrate support 3 is grounded, and the potential of the substrate 2 is set to the ground potential.

In this state, a red-purple plasma jet gas is blown onto the substrate 2 to deposit and form diamond on the substrate 2. In this embodiment, the temperature at the center of the plasma is 3000 ° C. or higher, and the discharge portion inside the gun rises more.

The evaluation results of the surface deposits on the substrate 2 actually synthesized for 30 minutes under the above conditions will be described. In addition,
A tungsten metal plate is used as the substrate 2, and its surface is finely scratched in advance by polishing so that a diamond film can be easily synthesized. Then, a Raman spectrometer and an electron microscope were used for observation of the deposit on the substrate 2. FIG.
(A) shows the relationship between the Raman shift and the peak height in the present embodiment. FIG. 2B shows the relationship between the Raman shift and the peak height when no electric field is applied by the plasma current power supply 21 in the configuration shown in FIG. 1 for comparison.

From this Raman spectrum, FIG.
As shown in the figure, a Raman peak having a Raman shift around 1333 cm ^-1 indicating the presence of diamond was confirmed. In FIG. 2B, from this Raman spectrum, 1400 to 1600c indicating graphite amorphous carbon, i-carbon and the like are shown.
A broad peak at m ^-1 clearly appears. From the results shown in FIGS. 2A and 2B, it is understood that a high-purity diamond film can be deposited and formed by applying an electric field from the power source 21 for plasma current. Note that a crystal particle image was also confirmed by observation with an electron microscope, and the crystal form showed the same form as the diamond particles synthesized by the microwave plasma CVD method.

The diamond film was synthesized at a rate of 0.3 μm / h in a diamond synthesis experiment performed using microwave plasma CVD, which was conventionally known. Is 10
It can be synthesized at a sufficiently high synthesis rate of 0 μm / h.

Next, as in the above embodiment, an electric field is applied between the rod-shaped electrode 7 and the ring-shaped positive electrode 31 by the plasma current power supply 21 to flow a current through the plasma, thereby obtaining high-purity diamond. The reason why the film can be deposited and formed at a high synthesis rate will be described below based on the considerations of the present inventors.

The method of synthesizing a diamond film using arc discharge is a method of synthesizing a diamond film by sufficiently decomposing a gas by the heat energy of the arc discharge, and the gases used are generally hydrocarbons and hydrogen. Considering the role of gas, hydrocarbons are decomposed by plasma decomposition to produce diamond, graphite, amorphous carbon, and i-carbon. On the other hand, hydrogen is considered to be decomposed by plasma decomposition to become hydrogen radicals, hydrogen ions, and the like. Since the hydrogen radical has a large reducing power, it has a function of reducing carbon and evaporating it to methane or the like. That is, the hydrogen radicals reduce diamond, graphite, amorphous carbon, i-carbon, and the like, which are generated by hydrocarbon decomposition by plasma.

Here, the reducing ability of hydrogen radicals to diamond, graphite, amorphous carbon and i-carbon, that is, the removing ability is different from each other, and the removing ability to diamond is other graphite, amorphous carbon and i-carbon. It is much lower than the removal ability for carbon. Therefore, in the synthesis of diamond by plasma decomposition, graphite other than diamond, amorphous carbon, i-carbon and the like are apparently selectively removed by hydrogen radicals, and only diamond is synthesized.

Therefore, in order to improve the synthesis rate and purity of diamond, it is necessary not only to increase the amount of introduced hydrocarbons but also to improve the decomposition (dissociation) of hydrogen and hydrocarbons. For example, when the dissociation rate of hydrogen with respect to the gas temperature is calculated by statistical mechanics, a graph shown in FIG. 4 is obtained. According to this graph, hydrogen is not dissociated by several percent at about 2,000 and several hundreds K, for example, as in the hot filament method. In order to highly dissociate hydrogen, a gas temperature of at least 3,000 K is required. Here, the arc discharge is several To
It is a discharge that occurs in the pressure range of rr to several atmospheres and a high-density current flows in the space instead of the potential difference between the counter electrodes being as low as several tens of volts. Therefore, it is considered that hydrogen can be sufficiently dissociated.

The rod-shaped electrode 7 and the ring-shaped positive electrode 31
When an electric field is applied by the plasma current power supply 21 during this time, the electrons flowing in the gas plasma are accelerated toward the ring-shaped positive electrode 31, and the energy of the electrons increases. When the electrons collide with hydrogen and hydrocarbons, the energy is absorbed by hydrogen and hydrocarbons. As a result, the hydrogen and hydrocarbons are easily decomposed and dissociated. It is considered that precipitation can be formed.

Here, the current flows in the plasma, and the larger the value, the higher the purity and the synthesis rate of the diamond film formed by deposition. By the way, when the current flowing through the plasma is increased, the accelerated electrons reach the substrate 2 and the substrate temperature is set to 6 which is the above-mentioned diamond synthesis region.
It is conceivable to raise the temperature from 00 to 1100 ° C,
In this embodiment, the substrate potential is set to the ground potential, and a positive current flows from the substrate 2 side to the ring-shaped positive electrode 31 so that the substrate temperature does not rise.

When the amount of current flowing in the plasma is small, the number of electrons involved in hydrogen dissociation decreases, and the effect on hydrogen dissociation decreases. In this case, it is conceivable to dissociate hydrogen near the substrate by bringing the ring-shaped positive electrode 31 closer to the substrate 2. However, as shown in FIG. While dissociation is improved, it is feared that the temperature of the substrate rises and the generation of impurity carbon such as graphite other than diamond sharply increases as described above. FIG. 6 shows a change in the substrate temperature when the distance between the ring-shaped positive electrode 31 and the substrate 2 is changed and a dissociation of hydrogen at 5 mm above the substrate 2 when a current of 40 A flows in the plasma. It shows a change in state.

The present inventors have made the ring-shaped positive electrode 31
Focusing on setting the amount of current flowing in the plasma so that it is in the optimal range for the diamond film to produce high purity, rather than by approaching When a current of 20 A or more is passed, a high-purity diamond film is generated. According to the position of the ring-shaped positive electrode 31 disposed with respect to the plasma jet gas ejected from the plasma ejection port 18,
The maximum diameter of the plasma jet gas between the ring-shaped positive electrode 31 and the plasma outlet 18 is represented by D (D ≦ C; C
(The maximum diameter of the plasma jet gas), it was found that the current density should be about 20 / D ² or more.
FIG. 5 is a characteristic diagram showing the relationship.

FIG. 5 shows the ring-shaped positive electrode 31 and the rod-shaped electrode 7.
5 shows changes in the thermal diffusivity (corresponding to the purity of the diamond film) of the synthesized diamond film and changes in the dissociation state of hydrogen at 5 mm above the substrate 2 when the amount of current flowing between them is changed. Note that the dissociation state of hydrogen is represented as emission intensity of hydrogen radicals using emission spectroscopy. FIG.
As can be seen from the figure, as the amount of current increases, hydrogen dissociation is promoted, and as a result, the purity of the diamond film is also improved. Moreover, it can be seen that when the current flowing from the ring-shaped positive electrode 31 into the plasma is about 20 A or more, the purity of diamond is significantly improved. In the above embodiment, the maximum diameter of the plasma jet gas is about 20 mm, and the ring-shaped positive electrode 31 is arranged at a position where the maximum diameter of the plasma jet gas is at least 5 A / cm ^2.
With the above current density, the purity of the synthesized diamond is remarkably improved.

Next, in this embodiment, the ring-shaped positive electrode 3
The reason why the inner diameter A of the first ring is defined as A ≦ 5B with respect to the inner diameter B of the plasma ejection port 18 will be described. In the present embodiment, the ring-shaped positive electrode 31 is disposed at or near the position where the plasma jet column has the maximum diameter so that the plasma jet column of the raw material gas passes through the ring. The purpose is to flow a large amount of electrons. Here, the ring-shaped positive electrode 31
When the inner diameter of the ring is larger than 5 times the inner diameter of the plasma jet port 18, the synthesis rate and the thermal diffusivity (corresponding to the purity of the diamond film) of the synthesized diamond film rapidly decrease. That is, the ring inner diameter A of the ring-shaped positive electrode 31
There is a correlation between A and 5B, which is suitable for flowing a large amount of electrons into the plasma, and the inner diameter of the ring-shaped positive electrode 31 is larger than this correlation. If it is set, it becomes difficult to flow electrons into the plasma.
This makes it difficult to flow a large amount of electrons through the plasma jet column to promote decomposition of the source gas.

Although the present invention has been described with reference to the first embodiment, the present invention is not limited thereto, and various modifications can be made without departing from the spirit thereof. FIG. 7 shows a diamond film manufacturing apparatus according to a second embodiment of the present invention. In the first embodiment, the ring-shaped positive electrode 31 is used as the plasma current positive electrode for flowing a current into the plasma. However, as in the present embodiment shown in FIG. 7, a simple rod-shaped positive electrode is used. The electrode 311 may be used.

As in the third embodiment of the present invention shown in FIG. 8, a counter electrode type positive electrode 312 composed of at least two electrodes may be used as a positive electrode for plasma current.

Furthermore, in the above various embodiments, the negative (low) potential side of the plasma current power supply 21 is connected to the rod-shaped electrode 7, but it may be connected to the cylinder-shaped electrode 10. In the first embodiment, the ring-shaped positive electrode 31 is
0, the ring-shaped positive electrode 31 is connected to the plasma jet gun 1 through the plasma jet 18.
The insulator 40 may be omitted, and the insulator 40 may be kept in the space between the plasma jet port 18 and the substrate 2. Further, in the various embodiments described above, the substrate 2 is set to the ground potential. However, it is sufficient to prevent the substrate temperature from rising due to the electrons reaching the substrate. The same potential as the positive electrode for
Alternatively, a power source for setting the substrate to a lower potential than the plasma current positive electrode may be connected to the substrate holding base so that the plasma current positive electrode has a higher potential than the substrate.

[0041]

As described above, according to the present invention, electrons are caused to flow in the plasma by setting the electrode side to a high potential between the region where gas plasma is generated and the positive electrode for plasma current arranged above the substrate. As a result, the decomposition of the source gas can be significantly improved, and the recombined source gas can be re-decomposed. Further, since the lower limit of the amount of current flowing in the plasma is set, the decomposition rate of gas in the vicinity of the substrate can be sufficiently increased without bringing the positive electrode for plasma current close to the substrate direction, and the synthesis rate can be increased. An excellent effect is obtained that a high-speed diamond film can be synthesized with high efficiency after being made faster.

[Brief description of the drawings]

FIG. 1 is a sectional view of a diamond film manufacturing apparatus according to a first embodiment of the present invention.

FIGS. 2A and 2B are characteristic diagrams showing the relationship between Raman shift and peak height. FIG. 2A is a characteristic diagram of a sample synthesized according to the first embodiment, and FIG. FIG. 4 is a characteristic diagram of a sample synthesized when no current is passed from the electrode into the gas plasma.

FIG. 3 is a characteristic diagram showing a distribution of hydrogen (H) radical spectrum intensity from a plasma ejection port toward a substrate.

FIG. 4 is a characteristic diagram showing a degree of dissociation of hydrogen with respect to a gas temperature.

FIG. 5 shows the change in the thermal diffusivity of the synthesized diamond film and the change in the dissociation state of hydrogen at a position of 5 mm above the substrate when the amount of current flowing in the plasma is changed in the first embodiment. It is a characteristic diagram.

FIG. 6 is a characteristic diagram showing changes in the substrate temperature when the distance between the ring-shaped positive electrode and the substrate is changed and changes in the dissociation state of hydrogen at a position of 5 mm above the substrate in the first embodiment. is there.

FIG. 7 is a sectional view of a diamond film manufacturing apparatus according to a second embodiment of the present invention.

FIG. 8 is a sectional view of a diamond film manufacturing apparatus according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma jet gun 2 Substrate 3 Substrate support 5 Vacuum container 7 Bar electrode 10 Cylindrical electrode 16 Gas introduction pipe 17 Power supply for arc discharge 18 Plasma ejection port 19 Carbon source gas introduction port 21 Power supply for plasma current 31 Ring-shaped positive electrode 40 Ring insulator

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadashi Hattori 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) C30B 1/00- 35/00 CA (STN) Patent file (PATOLIS) WPI / L (QUESTEL)

Claims (4)

(57) [Claims] 1. A vacuum vessel maintained at a predetermined degree of vacuum, a positive electrode and a negative electrode disposed in the vacuum vessel so as to face each other, and electrically connected to the positive electrode and the negative electrode, and between the positive electrode and the negative electrode. An arc discharge power supply for supplying a predetermined electric power to cause an arc discharge in the space, and a source gas containing at least hydrogen and carbon for the arc discharge to generate a gas plasma, and the gas plasma is supplied downstream thereof. Gas supply means for spraying the disposed substrate, a plasma current positive electrode disposed at a predetermined distance from the substrate between the region where the gas plasma is generated and the substrate, and the source gas A plasma current power supply for flowing a predetermined current from the plasma current positive electrode into the gas plasma to promote the decomposition of the plasma current positive electrode. The predetermined distance separating the substrate from the substrate is preset to a value at which the temperature of the substrate is prevented from rising due to the current flowing into the gas plasma by the power supply for plasma current. The apparatus for producing a diamond film, wherein a predetermined current flowing into the gas plasma by the power supply for plasma current is preset to a value of about 20 A or more. 2. The apparatus for producing a diamond film according to claim 1, wherein the potential of the positive electrode for plasma current is set to the same potential as the substrate or higher than the substrate potential. 3. The plasma current positive electrode has a ring shape, and the gas plasma is blown onto the substrate through the inside of the ring.
Or the apparatus for producing a diamond film according to 2. 4. A gas plasma is generated by flowing a raw material gas containing at least hydrogen and carbon into an arc discharge, and a diamond film is deposited on the substrate by spraying the gas plasma on a substrate disposed downstream thereof. In the forming method, a positive electrode for plasma current is disposed at a predetermined distance from the substrate between a region side where the gas plasma is generated and the substrate side, and the positive electrode for plasma current and the gas plasma are A method for producing a diamond film, characterized in that an electric field is applied so that the plasma current positive electrode has a high potential in order to flow a current of about 20 A or more between the region and the region where the plasma is generated.