RU2032765C1 - Method of diamond coating application from vapor phase and a device for it realization - Google Patents

Abstract

FIELD: instrumental industry. SUBSTANCE: method is realized by deposition from vapor phase by arc discharge during feeding of discharge gas between anode and cathode of device, heat plasma formation and chemical precipitation from vapor phase, radicalization of gaseous carbon compound after feeding of gaseous carbon compound to the plasma jet formed, and this radicalized plasma jet can contact with treated backing. As a result, diamond coating is formed on the backing. EFFECT: improved method of diamond coating application. 21 cl, 27 dwg

Description

 The invention relates to vapor deposition coatings in the tool industry and in electronic technology.

 Known method of deposition coating, providing a fast speed of application of this coating.

Various methods are also known as a method for applying a diamond coating to a compound, but even in the case of the best CVD method, the diamond deposition rate is 1 μm / h or less [2]
The purpose of the invention is to provide a method and apparatus for applying a diamond coating by vapor deposition on a substrate having a satisfactory coating layer thickness and good coating quality at a high deposition coating rate.

A method for applying a diamond coating by vapor deposition involves the steps of:
the formation of an arc discharge while supplying a discharge gas between the anode and cathode of the chemical vapor deposition device using thermal plasma;
radicalization (formation of radical groups) of the gaseous carbon compound by supplying gas to the formed plasma jet, and
making it possible for a radicalized plasma jet to fly onto the substrate to be treated, as a result of which a diamond coating forms on the substrate.

A method including the steps of:
supplying a gas containing hydrogen and a gaseous carbon compound to a thermal plasma generating apparatus having an anode and a cathode,
gas radicalization through an arc discharge of constant tissue between the electrodes,
injecting thermal plasma as a plasma jet into a reduced pressure chamber, and
abrupt cooling of the plasma jet by allowing the incandescent jet to fly onto the cooled substrate, with the result that a diamond layer is deposited on the substrate.

The method also includes the steps of:
the formation of an arc discharge by applying a direct current between the inner walls of a plurality of nozzles opening in a girdled housing forming an electrode of one polarity and a plurality of electrodes of another polarity opposing the nozzles, thereby radicalizing or activating hydrogen and a gas containing a carbon compound to form a thermal plasma;
injection of a plasma jet into a reduced pressure chamber;
abrupt cooling of the plasma jet by allowing the incandescent jet to fly onto the cooled substrate, resulting in a diamond coating deposited on the substrate.

 In accordance with the invention, there is also provided a plasma jet formation device, which (plasma jet formation device) includes a girdled (closed) housing having a discharge gas supply pipe, a supply pipe for starting gas or gas transporting solid particles, a direct current source and a conductive cable , and having a nozzle for injecting a plasma jet opening into it, characterized in that a plurality of nozzles open into it, with the inner walls correspondingly favoring nozzles form electrodes having the same polarity, respectively, and a plurality of electrodes having opposite polarity arranged inside the belted body so that they are located opposite the inner walls of the respective nozzles.

The method also includes the steps of:
supplying gas to the device for the formation of thermal plasma in the form of a burner (torch) having an anode and cathode;
gas radicalization as a result of a direct current arc discharge between the electrodes to form a thermal plasma;
injection of thermal plasma as a plasma jet through a nozzle at the end of the tip of the burner;
blowing cooling gas into the plasma jet to abruptly cool the thermal plasma and form an active nonequilibrium plasma containing at least groups of radicals formed as a result of radicalization of the carbon compound supplied to the plasma jet and having a high concentration of radicals and bringing the substrate into contact with nonequilibrium plasma, as a result of which a diamond coating is applied to the substrate.

 In accordance with the invention, there is also provided a method for applying a diamond coating by vapor deposition by forming an arc discharge using a direct current plasma torch having an anode and a cathode while supplying a discharge gas between the cathode and the anode, and directing the formed plasma jet onto the substrate to be treated to form a diamond coating on it, which includes the use of at least two plasma torches, forming gas at a higher voltage discharge in a plasma in one burner, forming a reactive gaseous carbon compound at a lower discharge voltage in a plasma in another burner, and allowing both plasmas to fly in the form of jets onto a substrate, thereby forming a diamond coating.

The method also includes the steps of:
use of multiple plasma torches;
the presentation of the possibility of multiple plasma jets to mutually collide with each other, and the formation of a carbon source in the plasma in these plasma jets for the formation of diamond.

The method also includes the steps of:
the formation of a discharge gas using an arc discharge and a source material containing at least a gaseous carbon compound in the plasma;
injection of thermal plasma in the form of a plasma jet;
abrupt cooling of the plasma jet for applying a diamond coating by deposition on a substrate in which at least the source material that destabilizes the arc discharge is fed to the center of the initiating end of the plasma jet without passing through the arc discharge section.

In FIG. 1 illustrates the principles of a thermal plasma CVD method; in FIG. 2 apparatus for a CVD method based on thermal plasma; in FIG. 3 embodiment of a method of synthesis from the vapor phase using thermal plasma; figure 4 the same option using plasma; figure 5 is a graph of changes in temperature of the equilibrium constant of the reaction of dissociation of a hydrogen molecule; Fig.6 device for the formation of a jet of thermal plasma, a sectional view; in FIG. 7 the same, bottom view; on Fig another device for the formation of a plasma jet, a sectional view; in Fig.9 a device for synthesizing from a vapor phase using a device for the formation of a plasma jet; figure 10 principles of synthesis from the vapor phase of the plasma using direct current fig.10b, fig.10c plasma torch, section; 11 is a drawing showing the state of a plasma jet in a state with synthesis from the vapor phase of the plasma using direct current; an embodiment of the invention; on Fig drawing showing the state of the plasma jet in accordance with the synthesis from the vapor phase of the plasma using direct current, another embodiment of the invention; 13 shows the formation of diamond on a substrate in accordance with a CVD method based on thermal plasma; on Fig device for a CVD method based on thermal plasma; on Fig principles of the CVD method based
plasma jet; in FIG. 16 is a general view of the device used to implement the CVD method based on a plasma jet; on Fig a view of the crystal structure of the diamond coating; on Fig a view of the crystal structure of the diamond coating in accordance with another embodiment of the invention; on Fig principles of the device for the injection of a plasma jet; in FIG. 20 SEM showing the surface of the diamond coating; in Fig.21 SEM showing the surface and sectional view of the diamond coating; on Fig a graph showing the results of x-ray diffraction of the diamond coating; in FIG. 23 is a graph showing a diamond coating spectrum according to Roman; in FIG. 24 vapor phase synthesis device based on a plasma jet using direct current and gas cooling; on Fig SEM, showing the surface of the diamond coating; on Fig SEI showing the surface and the cross-sectional view of a diamond coating; on Fig a graph showing the results of the diffraction of X-rays of the diamond coating; on Fig a graph showing the spectrum of the diamond coating according to Roman; on Fig graphs showing the spectra of emission and plasma jets using direct current according to the invention and traditional microwave plasma.

 The method is as follows.

 The diamond coating is deposited on the substrate to be processed by applying CVD devices based on thermal plasma, which is used to synthesize ceramic fine powder.

Figure 1 shows the principles of the thermal plasma method used in the CVD method, in which an arc discharge is produced as a result of applying voltage while passing the discharge gas 3 between the anode 1 and cathode 2, thereby forming an arc plasma having a temperature of 5000 ^o C or higher . The source gas 4 supplied to the arc plasma generation section through the inlet provided on the anode 1 is quickly heated to high temperature and activated, thereby forming high-density radicals simultaneously with the expansion of the volume to be injected, like an ultrahigh-speed plasma jet 6 through the nozzle 5.

Using the above method, an attempt was made to synthesize the powder of a compound with high precision melting, such as silicon carbide (SiC) or silicon nitride (Si ₃ N ₄ ). Experiments were carried out in which, to obtain SiC, silane (SiH ₄ ) and methane (CH ₄ ) were fed into the arc plasma as the source gases, and, to obtain Si ₃ N _4, SiH ₄ and ammonium (NH ₃ ) were introduced to activate and induce the formation of radicals to get the powder.

 The present invention aims to achieve coating formation by creating the possibility for a plasma jet 6 to fly onto the substrate 7 to be treated, thereby creating an effective CVD reaction on the substrate before the end of the short life of the radicals. Further, during the reaction on the substrate, the energy obtained through photoexcitation as a result of irradiation with ultraviolet rays generated during the arc discharge and collision of the plasma jet are added.

Generating radicals with a significantly higher density by activation in a high-temperature arc having a temperature above 5000 ^° C, and simultaneously supplying radicals to the treated substrate and cause the reaction of radicals as a result of energy from the above photoexcitation and collision, thereby producing effective diamond deposition.

In the synthesis of diamonds in accordance with the second embodiment of the proposed CVD, a gas mixture of a carbon compound such as methane, acetylene, alcohol, acetone, methylamine, dioroethane, with hydrogen decomposes to become active, and the diamond is deposited on the substrate at a temperature suitable for the deposition of diamond from vapor is from 400 to 1500 ^o C. in the synthesis of diamond is assumed that the active formation such as hydrogen atoms and hydrocarbon radicals, play an important role in the vapor phase, and to enhance the deposition rate of diamond pla ma high density of active formations may be formed and may be supplied on the substrate surface.

2H но при 5000 К можно понять, что почти все молекулы водорода диссоциированы в атомы водорода. Однако, когда тепловая плазма при этой температуре находится в контакте с подложкой, температура подлжки становится слишком высокой и становится трудно синтезировать алмаз.As a plasma with an extremely high activity and a high degree of dissociation of molecules, a thermal plasma is known in which the temperature of such various chemical formations as electron ions, neutral particles in the plasma is essentially the same and their temperature is 500 K or higher. In FIG. Figure 5 shows the change in the temperature of the equilibrium constant K (PH) ₂ / PH ₂ in the dissociation reaction of the hydrogen molecule H ₂

2H but at 5000 K it can be understood that almost all hydrogen molecules are dissociated into hydrogen atoms. However, when the thermal plasma at this temperature is in contact with the substrate, the substrate temperature becomes too high and it becomes difficult to synthesize diamond.

 In FIG. Figure 3 illustrates the synthesis of diamond using the CVD method based on a thermal plasma arc formed by a direct arc discharge.

When the arc 19 is discharged by applying a DC voltage between the anode 15 and the cathode 16 while the hydrogen-containing gas 17 and the gaseous carbon compound 18 are simultaneously flowing, the gas quickly heats between the narrow electrodes to become a thermal (heated) plasma having a temperature of 5000 ^o C or higher , around the nozzle 20. In this case, due to the river temperature increase, the volume expands, as a result of which the thermal plasma becomes a supersonic plasma jet 21, and is injected through the nozzle 20 into the chamber 22.

 In FIG. 29 shows the emission spectra of a plasma jet based on direct current in accordance with the invention and a conventional microwave plasma. Two spectra are normalized by the Ha peaks. In the microwave plasma, wide and strong emissions of hydrogen molecules (less than 480 nm, 560-620 nm) were noted. But in a direct current-based plasma jet, the emission associated with hydrogen molecules was very weak. These results mean that the degree of hydrogen dissociation is very high in the case of a direct current plasma jet compared to traditional microwave plasma.

 By abruptly cooling the plasma jet as a result of the collision of the plasma jet 21 with the substrate 24, in which such active formations as short-life hydrogen atoms are cooled with high efficiency, they react on the surface of the substrate before fading to synthesize a diamond coating 25.

 Further, in the reaction on the substrate, motion energies resulting from photoexcitation with the help of strong ultraviolet rays generated during an arc discharge, and as a result of collisions between supersonic particles, are added. Accordingly, the chemical reaction can be carried out with higher efficiency compared to the known method, and therefore diamond can be synthesized with a high deposition rate.

 In the present invention, any carbon compound can be used as a source gas, but carbon or halogenated carbon containing oxygen, nitrogen or halogen in the molecule is preferably used.

 Arc discharge stability can be improved by mixing an inert gas such as argon, helium, etc. when the source gas is added to the hydrogen and the carbon compound of the source gas. In this case, although the deposition rate of the coating can be reduced, it is advantageously achieved in that the uniformity of the surface of the coating is enhanced.

 Also by mixing a small amount of oxidizing gas, such as oxygen, water, hydrogen peroxide, carbon monoxide, etc. the effect of non-diamond carbon as a result of etching can be enhanced. The source gas 18 can be supplied together with the hydrogen of the discharge gas 17 between the electrodes, but as shown in FIG. 4, it can also be supplied to the plasma jet 21 injected from the zone between the electrodes. However, in this case, the source gas must be supplied uniformly into the thermal plasma jet.

 Since hydrogen, which is difficult to discharge at a high ionization potential, as shown in FIG. 5, is used as a discharge gas, electrode metals should preferably have high thermal resistance. Tungsten having a rare earth oxide such as lanthanum oxide, yttrium oxide, cerium oxide, etc. added to it is an excellent electrode material. Further, a carbon electrode having a high purity is preferably used to prevent entrainment of impurities from the electrodes.

According to a third embodiment of the invention, since the thermal plasma during heating is heated to a high temperature of about 5000 ^° C, it expands sharply and is injected through a nozzle. Since the nozzle has a narrow hole from 1 to 2 mm, the area of the cooled substrate, with which the jet from one nozzle collides, is about 25 mm ² .

 The plasma jet is injected through a plurality of nozzles, and therefore, the deposition area of the coating can be expanded.

 The uniformity of the coating during deposition can also be improved by mixing an inert gas, such as argon or helium, or with hydrogen from the discharge gas, or with the carbon compound of the source gas, or both, or an oxidizing gas such as oxygen, hydrogen peroxide or water can be mixed to remove non-diamond carbons mixed in the coating formed by etching.

 The device for the formation of a plasma jet, as shown in Fig.6, includes in a girdled (closed) housing for the formation of the anode 26 and the cathode 27 mounted with an insulating element inside it. The discharge gas supply pipe 28 is opened into the encircled housing, and the source gas or gas transporting pipe 29 is opened into the interior of a plurality of nozzles 31 formed on the electrode. A DC voltage is supplied to the electrodes from the conductive conductor (cable) 31 to form a continuous arc discharge between the electrodes, as a result of which the discharge gas and the source gas are activated to form a plasma jet 33 having a high temperature.

For chemical vapor deposition diamond coating, as shown in FIG. 9, a thermal plasma generation device is mounted in a reduced pressure chamber 37, and it has a substrate holder 36 cooled by water to hold the substrate 35 opposite the nozzles 31. FIG. 7 shows four nozzles 31, each of which has a hole of 2 mm, the distance between the centers of the nozzles is 5 mm at least, and a substrate 35 of size 20 mm ^{2 is} set 10 mm below the nozzles 31. The pressure in the chamber was reduced to 100 torr, hydrogen gas is supplied from flow rate 1000 SOCM from pit a discharge gas supply pipe 28, and methane with a flow rate of 100 SCCM to the nozzle 31 from the feed gas supply pipe 29. A DC power of 2 kV is applied between the electrodes and the plasma jet 33 formed by an arc discharge is subjected to rapid cooling by continuous impact with the substrate for 1 h, resulting in a diamond coating having a layer thickness of about 80 μm and an area of about 4 cm ² . The area of this coating is 16 times larger than that obtained using a single nozzle. The feed gas supply pipe 21 may also open outside the nozzle 31, as shown in FIG. 8, to inject gas into the plasma jet.

 According to the invention, the chemical method of applying a diamond coating by vapor deposition based on a plasma jet using direct current makes it possible to produce a coating at a high speed, and the area forming the coating can be significantly increased, and thus there can be an improvement in cost and productivity .

 In the above example, a plasma jet is used to chemically precipitate diamond from the vapor phase, but it is also possible to supply a powder containing an inorganic substance or a metal substance transported together with a gas, for example argon, through a feed pipe of a source gas, or a gas transporting a liquid or thin solids particles into the interior of the nozzle 31, and melt the inorganic substance or the metal substance using a plasma jet, thereby forming a coating on the substrate by spraying the plasma.

As shown in FIG. 8, powdered fine particles of an inorganic substance or metal substance can be transported by gas argon, etc., through a feed pipe 29 of a source gas or gas carrying a liquid or solid fine particles opening outside the nozzle 31. and blowing into a plasma jet. Refractory metals, superalloys, cermet, etc. can be used as a metal substance. As an inorganic substance, a superconducting substance of the 2-Ba-Cu-O system, Bi-Sz-Ca-Cu-O system, ceramics, graphite, glass, etc. As an inorganic substance, a powder, for example, a superconducting ceramic powder of the U system -Ba-Cu-O, is supplied through a gas feed pipe to form a coating by plasma spraying with a thickness of about 1000 microns and an area of about 4 cm ² . This coating by plasma spraying showed superconductivity at a temperature of liquid nitrogen, with an electrical resistance of "0" at an absolute temperature of 88.5 K.

 According to a fourth embodiment of the invention, instead of abrupt cooling of thermal plasma as a result of collision with a cooled substrate, a method of injecting gas into a plasma jet (gas cooling method) is used.

This method creates a nonequilibrium plasma regardless of the substrate, because the thermal plasma cools instantly as a result of forced mixing of the plasma jet with a gas of room temperature. Accordingly, by maintaining the processed substance in a non-equilibrium plasma at a temperature corresponding to the formation of diamond, diamond can be synthesized on the surface at a high speed. The preferred temperature of the substrate is from 800 to 1300 ^o C.

 In FIG. 10 shows the principles of diamond synthesis according to the CVD method based on a plasma jet using direct current by gas cooling.

 The device has a cathode 38, anode 39, discharge gas 40, nozzle 41, plasma jet 42, an outlet from the injection of cooling gas, cooling gas 44, substrates 45, diamond coating 46, there is an arc discharge power source 47, arc 48 and non-uniform plasma 49 As a plasma torch 50, a torch having a single electrode can be used, as n is shown in FIG. 10, or a burner having a plurality of electrodes, as shown in FIG. 10 c.

During the flow of the discharge gas 40 containing hydrogen gas and a gaseous carbon compound, a DC voltage is applied between the cathode 38 and the anode 39 to excite the arc discharge 48, whereby the discharge gas is rapidly heated to form a thermal plasma having a temperature of 5000 ^° C. or higher, near the nozzle 41. During this operation, due to volume expansion caused by a sharp increase in temperature, the thermal plasma becomes a supersonic plasma jet 42 and is injected through the nozzle 41. Hydrogen gas is injected as cooling gas 44 against the plasma jet 42 for the formation of forced mixing, thereby sharply cooling the thermal plasma to form a non-equilibrium plasma 49. By placing the substrate 45 in a non-equilibrium plasma 49, active formations such as hydrogen aromas with a short service life react before attenuation on the substrate forming a diamond coating 46 on its surface.

 11 a and FIG. 11c, 12a and 12c show a plasma jet when a flow of cooling gas is passed through. In the case of FIGS. 12 a and 12 c, when a cooling gas is supplied, the length of the plasma jet must be very short in order to abruptly cool the thermal plasma. Therefore, since the thermal plasma is rapidly cooled irrespective of the substrate, there is no restriction on the type of substrate that can be used, and thus, diamond can be grown at high speed on any substrate.

 In the present invention, any hydrocarbon can be used as a source gas, but it is preferable to use a hydrocarbon or halogenated carbon containing oxygen, nitrogen and halogen in the molecule. By mixing an inert gas such as argon, helium in the case of hydrogen, and a carbon compound of the source gas of the discharge gas, the stability of the arc discharge can be improved. In this case, although the deposition rate of the coating may decrease, it is advantageously achieved in that the uniformity of the surface of the coating is improved. Also by mixing a small amount of oxidizing gas, such as water, hydrogen peroxide, carbon monoxide, the effect of eliminating non-diamond carbon by etching can be enhanced. Since hydrogen, which has a high ionization potential and is difficult to discharge, is used as the discharge gas, the electrode materials preferably have high thermal resistance. Tungsten having a rare earth oxide such as lanthanum oxide, yttrium oxide, selenium oxide, etc. added to it is an excellent electrode material. Further, a high purity carbon electrode is preferably used to prevent trapping of impurities from the electrodes.

 As mentioned above, the methods for synthesizing a diamond coating of the prior art are not industrially satisfactory, and according to a fourth embodiment of the present invention, a new method for synthesizing a diamond coating using the plasma spraying principle has been created, and it becomes possible to synthesize a diamond coating on a substrate commercially.

 However, in this method, in which, for example, a gas mixture of hydrogen and a gaseous carbon compound such as methane is used as gas and is chemically vapor-deposited to form a diamond coating using a thermal plasma CVD device, the problem arises in the sense that the discharge becomes unstable, and a stable plasma jet is not achieved due to, for example: a very high discharge voltage of hydrogen; heat generation and volume expansion due to methane decomposition; the reaction of carbon formed by the decomposition of methane associated with the electrode of a plasma atomization device on which methane is decomposed. As a result, the temperature of the substrate and the injected amount of plasma changes, and a uniform diamond coating cannot be synthesized.

In FIG. 13 shows the principles of the CVD method based on the thermal plasma mentioned above, in which an arc discharge 57 is excited by applying a voltage of a DC power supply 56 while passing a discharge gas (H ₂ + CH ₄ ) 55 between the anode 53 and the cathode 54 to form an arc plasma 5000 ^o C or higher.

The source gas 55, supplied to the arc plasma forming portion of the plasma torch 63, is rapidly heated to high temperature to activate and create radicals at high density, as a result of which the volume expands, and the plasma is injected with ultrasonic high speed through the nozzle like a plasma jet 58. Plasma the jet 58 is specially directed before collision with the substrate 59 to be processed in order to form a CVD reaction with good efficiency on the substrate before radical attenuation with a short service life, thereby m forming a diamond coating 60. The substrate 59 used for this purpose is placed on the holder 61 of the substrate with cooled water and cooling water 62 supplied to the water-cooled holder 61, to a temperature of, for example, from 400 to 1500 ^° C, preferably from 800 to 1300 ^o C.

However, as described above, although the diamond coating can be effectively deposited on the substrate from the vapor phase, a stable plasma jet cannot be achieved for the above reasons, thereby creating the problem that a uniform diamond coating cannot be obtained. Conversely, according to the present invention, as shown in FIG. 14, two plasma torches 64 and 65 are used, and H ₂ gas (or a gas mixture of H ₂ and inert gas according to the traditional method) is introduced into one burner, while methane gas (CH ₄ ) or a gas mixture of methane and inert gas as an organ ( is introduced into another torch, and the arc discharge is excited by applying voltages between the anodes 66 and 67 and the cathodes 68 and 69, respectively, from the DC power supplies 70 and 71, thereby injecting the plasma jets 72 and 73. These plasma jets deposit a uniform diamond coating 76 on substrate 75 placed on water cooled substrate holder 74.

 It has been established that a large number of thin diamond nuclei (nuclei) are formed due to the possibility of many plasma jets to mutually collide with each other, forming a carbon-containing compound in the plasma of the plasma jets, and abrupt cooling of the compound. Accordingly, a smooth diamond coating of excellent uniformity can be obtained, differing from the prior art in which only a few diamond cores (nuclei) were grown, and as a result, the surface of the diamond coating was uneven, according to a sixth embodiment of the present invention.

 In FIG. 15 shows the principles of a device in which another burner is mounted to form a plasma jet on one device using the CVD method based on thermal plasma. The device has an anode 78, a cathode 79, a discharge gas 80 or a discharge gas containing a source gas, a cooling gas 81 or a cooling gas containing a source gas, an arc 82, a nozzle 83, 84 a plasma jet, a vacuum chamber 85, a substrate holder 86, 87 a substrate 87 and diamond coating 88.

 In FIG. 16 shows a General view of the device for implementing the invention. It has a first plasma torch 89, a second plasma torch 90, arc sources 91 and 92 for the respective torches 93 and 94, water-cooling devices for the respective torches, a substrate manipulator 95, a torch manipulator 96, 97, a gas bomb 98, a flow meter 99, and a discharge gas and a discharge gas supply pipe 100 containing a source gas, a source gas and / or a cooling gas supply pipe 101, a cooling gas discharge pipe 102.

A Si (silicon) substrate 86 87.5 cm ^{2 is} installed 100 mm below the 89 burner, and after evacuation to 1x10 ^-2 Torr, a discharge gas H ₂ at 50 SLM and a source gas CH ₄ at 500 S CCM are fed to the burner 89 with a discharge power of 3 kW and a pressure in the system of 100 torr. At the same time, when the discharge gas H ₂ at 20 SLM and the source gas at 100 S CCM at a discharge power of I kW are supplied to the burner 90, a coating is formed using the burner at a distance of 5 mm from the substrate and at an angle of 60 ^° from the substrate for 1 h. When this coating was analyzed by Raman spectroscopy and X-ray diffraction, it was found that a coating showing the peak of diamond was obtained. In FIG. 17 shows a diamond coating obtained using two plasma torches in accordance with the invention and having a layer thickness of 35 μm, where the coating formation rate was 100 μm / h. FIG. 18 shows a diamond coating obtained with a plasma torch 89 only. A diamond having a uniform uniform surface can thus be obtained at high speed.

In the above example, hydrogen is supplied from the discharge gas supply pipe 100 and methane from the source gas supply pipe 101 to the plasma torches 89 and 90, but it is also possible to supply hydrogen and methane from the discharge gas supply pipe 100, or to supply chilled H ₂ gas and methane from the supply pipe 101 of the source gas and / or cooling gas. Various modifications can also take place, for example, the supply of a discharge gas and a source gas to only one of the plasma torches, and only a discharge gas to the other plasma torch, etc. The bottom line is that many plasma jets are emitted and a carbon source is formed in the plasma of the plasma jets to form diamond on the substrate. With respect to the angles at which a plurality of plasma jets are preferably set in terms of the deposition rate of the coating, it should be vertical to the substrate, but if necessary, plasma jets can be installed at any optimal given angle.

 As a plurality of plasma jets, direct current plasma jets using a direct current arc discharge were indicated, but it is also possible to use many different types of plasmas, for example a PF plasma jet using a high-frequency discharge, an optical plasma arc jet using an optical arc discharge using a laser beam, and a plasma jet using a microwave plasma jet based on a microdischarge discharge of an alternating current. As an atmosphere for plasma formation, a reduced pressure atmosphere is preferred, but atmospheric pressure or a high pressure atmosphere can also be used to form diamond. Further, this method can also be used for the synthesis of diamond powder.

 According to a sixth embodiment of the present invention, in a DC-current CVD plasma jet method, a diamond coating can be obtained at a high speed and will have a smooth and uniform surface, so that the volume or range of application of the coating can be expanded to a significant degree.

 A diamond heat sink or substrate with a diamond circuit for a semiconductor device can also be easily implemented.

 The epitaxial method of growing a diamond coating in a seventh embodiment of the invention involves injecting a source material containing a supplied carbon source into a plasma and growing diamond by quenching the thermal plasma.

In a diamond growing method, hydrogen is usually used as the discharge gas and any carbon compound can be used as the source gas for the carbon source, but it is preferable to use a hydrocarbon or organic substance containing O, N, halogen, etc. in the molecule. An inert gas, for example, helium, can also be mixed in the discharge gas or feed gas. In this case, to enhance the etching effect of non-diamond carbon, for example carbon, a small amount of oxidizing gas O ₂ , H ₂ O, H ₂ O ₂ , CO can also be mixed with the source gas. Further, by mixing a small amount of gas, for example B ₂ H ₆ , NH ₃ , pH ₃ , with the source gas or by supplying the first mentioned gas separately to the plasma jet, it is also possible to obtain a semiconductor diamond.

 The source gas is supplied to the center of the initiating end of the plasma jet without passing through the arc discharge section. For this purpose, it is advantageous to use a plasma injection device. When a plasma jet injection device is used for plasma spraying a high temperature superconducting oxide (BA-Y-Cu-O system, Bi-Sz-Ca-Cu-O system, etc.), the superconducting oxide fine powder is supplied together with the carrier gas 109 ( Fig. 19) for plasma melting and effective coating formation not on the substrate. In this case, an oxidizing atmosphere can be used as a plasma atmosphere: oxygen, air.

 In FIG. 19 shows the principles of growing diamond coatings using the proposed device.

 19, 103 denotes a cathode, 104 anode, 105 discharge gas, 106 nozzle, 107 plasma jet, 108 injection gas outlet, 109 source gas, 110 substrate, 111 diamond coating, 112 arc discharge power source and 113 arcs.

 The plasma jet injection device, as shown in FIG. 19, has a feed hole for the source gas (or for a gas containing powdered source material) 109 located along the central axis of the inner electrode 103, and the outlet for the injection of source gas 108 is located in the center of the injection the nozzle 106 of the outer electrode 104, and the arc 113 is discharged between the electrode 103 and the outer electrode 104, but the source gas (or gas containing a powdery source material) 109 will not come into contact with the arc 113. Accordingly, one orodnoe arcing 113 will not be violated. In addition, since the source gas (or gas containing the powdered source material) 109 is directed to the central portion of the initiating end of the plasma jet 107, the distribution of the plasma formed in the plasma jet 107 can be made uniform and used to form and grow the deposited product by using for this vapor deposition or thermal plasma, whereby a uniform and even coating can be grown. It should be noted that by using this device for growing diamond and material as a non-diamond substrate, polycrystalline diamond can be synthesized on the surface.

 This device is capable of supplying the source gas through an injection outlet formed in the center of the cathode to the plasma jet so as to uniformly supply the source gas to the plasma jet, thereby improving the uniformity of the coating thickness, or the formation of graphite in the case of the source gas, which is a carbon compound.

When the flow rate of hydrogen gas 1, 1 min as a discharge gas 105 and methane gas with a speed of 0.2 l per 1 min as a source gas 109, a DC voltage of 90 V, 10 A is supplied between the anode 104 and the cathode 103 to excite the arc discharge 113 whereby the discharge gas is heated to become a thermal plasma having a temperature of 5000 ^° C or higher around the nozzle 106. In this case, due to volume expansion caused by a sharp increase in temperature, the thermal plasma becomes a supersonic plasma jet 107 that is injected through the nozzle 106. The source gas does not pass through the arc discharge section, but is supplied directly to the plasma jet in order to decompose and activate. The plasma jet is rapidly cooled as a result of collision with a 5 × 5 × 0.5 mm molybdenum substrate in order to grow a diamond coating, and as a result, a polycrystalline diamond coating of 200 μm was obtained for 1 h. When the surface roughness was measured, it turned out to be 10 μm, which was a significant improvement over 50 μm by a known method in which the feed gas was supplied together with the discharge gas. In this device, since the source gas is not contained in the arc, a stable discharge can be achieved. And yet, since all of the feed gas is fed into the plasma jet, the formation of graphite is also prevented.

 In the case of growing diamond, it is advantageous to use hydrogen, which can be discharged only with great difficulty due to the high ionization potential, it is preferable to use electrode material having high thermal resistance and capable of forming a stable discharge. Tungsten, having lanthanum oxide, yttrium oxide, cerium oxide added to it, is an excellent electrode material. To prevent trapping of impurities from the electrode, a carbon electrode having a high purity is also used.

 Example 1 (figures 1 and 2).

 In FIG. 2 gives a device for the formation of thermal plasma. In the device there is a holder 9 of the substrate opposite the plasma torch 8, which (holder) is cooled by water, and the processed substrate 7 is placed on it. The device is also connected to an exhaust system 10 with a plasma torch 8, a discharge gas supply pipe 11 is connected to supply the latter between the discharge electrodes 1 and 2, and a source gas supply pipe 12 for supplying the latter to the arc plasma, and also an arc supply source 13 for supplying power to the discharge electrodes 1 and 2 and a bias power supply 14 for concentrating radicals on the treated substrate 7.

Below, by way of example, a silicon (Si) substrate of 30 mm ^{2 is} treated, and an interval of 300 mm is maintained between the substrate and the plasma torch 8. After the device inside has been evacuated to 1x10 ^-2 Torr, using an exhaust system 10 it delivers hydrogen gas (H ₂ ) at a speed of 1000 S CCCM through the discharge gas supply pipe 11, and methane gas (CH ₄ ) is supplied at a speed of 100 S CCM through the feed pipe 12 of the source material, and in the chamber the degree of vacuum is maintained at 100 torr using the exhaust system 10. Then, 2 kV was applied as an arc power source, and 300 V as a bias voltage. Then, after CVD on the basis of thermal plasma, a diamond coating is formed with a thickness of about 10 μm for 1 h and its analysis using Raman spectroscopy and X-ray diffraction shows only the peak of diamond.

 This deposition rate was higher on Icipher or more compared to the prior art CVD in which the deposition rate l was 1 μm or less.

 Since radicals are formed with a very high density, diamond can be formed with a deposition rate higher than Icipher compared with the prior art, so that the demand for substrates for LSI can be satisfied.

PRI me R 2 (figure 3). Anode 15 and cathode 16 are made of tungsten having 2 weight. yttrium oxide added to it: the plasma torch has water cooling and is fixedly mounted on the manipulator (not shown) in the chamber 22 with the ability to change the direction of the nozzle 20. The water-cooled substrate holder 23 is movable in the vertical direction and / or lateral, and the nozzle-substrate distance is variable . Silicon wafer 24 with a size of 5 mm ² and a thickness of 0.2 mm is fixed on the holder 23 of the substrate, and then the chamber 22 is evacuated to 2 ^. 10 ^-3 torr, as shown in figure 3. H ₂ is supplied at a flow rate of 20 l in 1 min under a pressure of 1 kg / cm ² , and CH ₄ as feed gas 18 is supplied at a speed of 40 cm ³ / min, at a pressure of 1 kg / cm ² between the electrodes, while the pressure in the chamber 22 is maintained at 100 torr. From a DC arc source, a current of 10 A is passed between the electrodes and maintained for about 5 minutes, until the voltage becomes constant. The voltage at this moment is 72 V. The water-cooled holder of the substrate 23 is slowly approaching the nozzle 20, the distance between the nozzle and the substrate was 5 mm, and diamond synthesis is carried out under these conditions for 1 h. The synthesized diamond is evaluated by photographing with a solution of an electron microscope (SEM) ), X-ray diffraction, Raman spectroscopy and hardness measurements. 22 is maintained at 100 torr. From a DC arc source, a current of 10 A is passed between the electrodes and maintained for about 5 minutes, until the voltage becomes constant. The voltage at this moment is 72 V. The water-cooled holder of the substrate 23 is slowly approaching the nozzle 20, the distance between the nozzle and the substrate was 5 mm, and diamond synthesis is carried out under these conditions for 1 h. The synthesized diamond is evaluated by photographing with a solution of an electron microscope (SEM) ), X-ray diffraction, Raman spectroscopy and hardness measurements.

As shown in FIG. 20, the surface of the diamond coating consists of diamond crystals arranged regularly grouped together. SEM in FIG. 21 also shows a central portion, which is a cross-sectional view of a diamond coating, a lower portion, which is a cross-sectional view of a silicon substrate, and an upper portion that is a surface of a diamond coating. It can be understood that the surface of the diamond coating is uniformly formed with a slight unevenness. On Fig shows a x-ray diffraction pattern of a diamond coating with diamond crystalline phases (111), (220), (311), visible very clearly, and also noticeable (331) and (400). In FIG. 23 shows a Raman spectrum of a diamond coating in which a peak inherent in diamond can also be recognized at a wave number of 1333 cm ⁻¹ , and it is easy to understand that no peak of other carbon materials like graphite was detected.

Regarding the Vickers hardness H500, the assessment of the pressure mark was difficult due to the high hardness of the sample, but it was found to be 8000 kg / cm ² or higher. From the above data, it was clear that the synthesized diamond is a polycrystalline coating with good quality. The coating thickness was 80 μm, and a good quality diamond coating was synthesized at a high speed exceeding 10 times or more the speed of the prior art of 80 μm / h.

 The synthesis is carried out for 10 hours and under these conditions, the coating thickness is about 1 mm in the central part of the substrate, and 0.6 mm in its peripheral regions. Even after measurements using x-ray diffraction and the Raman spectrum, only a diamond peak was detected and no graphite was observed.

PRI me R 3 (figure 4). Using a Mo (molybdenum) plate of size 10x10x10.2 mm as a position, as shown in Fig. 4, H ₂ gas as a discharge gas 17 is supplied at a rate of 20 l in 1 min, argon gas at a speed of 20 l in 1 min, gas argon containing 2% acetone as the source gas 18 is supplied at a speed of 2 L per 1 min into the plasma jet, and the diamond is synthesized for 1 h at an arc discharge current of 20 A, a voltage of 60 V, and a nozzle-substrate distance of 10 mm. The coating thickness was 60 μm, and the quality of the coating was similar to example 2.

 PRI me R s 4-9 (figure 3 and 4). The rates of formation of a diamond coating when the reaction conditions change, for example, by changing the supplied gas between the electrodes or by supplying gas to a thermal plasma jet formed between the electrodes, are summarized in Table 1 and Table 2. The quality of the layers of the obtained diamond coatings were similar to Example 2. According to the CVD method based on a plasma jet in accordance with the invention of good quality, a diamond can be deposited at a speed of 80 μm / h, which is significantly higher than the speed in the prior art, due to which great progress has been made forward on the practical use of low-cost diamond through vapor phase synthesis. When a diamond synthesized according to the method was used as a heat sink of a semiconductor or as a substrate of a circuit, a large reduction in cost and an improvement in performance are achieved.

 PRI me R 10 (Fig.24). On Fig shows a device for synthesizing diamond by the CVD method using a plasma jet based on direct current and cooling gas. It has a plasma torch 115, a discharge gas supply pipe 116, a cooling gas supply pipe 117, an arc discharge power supply 114, a burner cooling water pipe 118, a substrate holder 119, a substrate 120, a vacuum chamber 121, an exhaust system 122, a burner manipulator 123, a flow meter 124, a gas bomb 125, a cooling gas exhaust outlet 126, a substrate manipulator 127.

 The plasma torch has a water cooling device made of tungsten with the addition of 2 weight. yttrium oxide to it along with the anode and cathode. The position and direction of the plasma torch 115 and the substrate holder 119, respectively, can be controlled by manipulators, and therefore, the diamond coating can be uniformly grown on a large area substrate or processed material with a complex surface shape. Although not shown in FIG. 24, the substrate holder 119 may also be mounted with a heating device for heating the substrate or a water cooling device for controlling the temperature of the substrate.

PRI me R 11 (Fig.24). Using a silicon (Si) wafer 5 × 5 × 0.2 mm in size as a substrate, after the internal vacuum chamber has been evacuated to 2 × 10 ⁻³ Torr, hydrogen, as a discharge gas, is supplied at a speed of 20 l in 1 min under a pressure of 1 kg / cm ² and methane at a speed of 80 ml per 1 min under a pressure of 11 kg / cm ² is supplied between the electrodes, and hydrogen is supplied at a speed of 20 l per 1 min under a pressure of 1 kg / cm ² as a cooling gas to maintain the pressure in the vacuum chamber at 200 torr. The cooling gas supplied from the cooling gas supply pipe 117 is injected into the plasma jet through the four cooling gas injection outlets 126 located 3 mm below the burner nozzle. From a DC arc source 114, a 10 A current is supplied between both electrodes of the plasma torch 115 and maintained for 5 minutes until the voltage becomes constant. The voltage at this moment is 65 V. By approaching the substrate holder 119 with the burner nozzle 115, the nozzle-substrate distance is set to 5 mm, and the coating is formed in this state for 10 minutes. The resulting diamond is evaluated in accordance with a SEM scanning electron microscope, X-ray diffraction, Raman spectroscopy, and hardness measurements.

 From the SEM shown in FIG. 25, it can be seen that the surface of the diamond has regular-arranged diamond crystals grouped together. On the other hand, in FIG. 26, SEM shows a cross-sectional view of a diamond in a central part, and a cross-sectional view of a silicon substrate in a lower part, as well as a diamond coating surface in an upper part, and it can be seen that a diamond coating surface is uniformly formed with slight irregularities. You can also see that the synthesized diamond is dense polycrystalline, having a distinct intrinsic shape, and that the coating thickness is about 15 μm.

In FIG. 27 shows a X-ray diffraction pattern of a diamond coating using the CX1 line and diamond crystal faces (111), (220), (311), which are very pronounced, as well as (331) and (400), which were also recognized. Thus, only sharp peaks of cubic crystalline diamond were detected. On Fig shows the Raman spectrum of the diamond coating, in which the peak immanent in the diamond can also be recognized at a wave number of 1333 cm ^-1 , and it can also be seen that the peak of other carbon materials, such as graphite, is not detected. In terms of Vickers hardness, this value was determined to be equal to natural diamond at about 10,000 kg / cm ² under a load of 500 g. From the above results, it can be understood that the synthesized diamond is a good quality semi-crystalline coating. You can also understand that the deposition rate of the coating is so high and equal to 100 μm / h.

 PRI me R 12 (Fig.24). When a 10 x 10 x 1 mm platinum plate is used as a substrate under the coating conditions of Example 11, and then the plasma torch is scanned (moved) along the platinum plate at a speed of 2 mm / h, it forms a 0.4 mm thick diamond coating on the platinum plate. The diamond coating is then peeled off from the platinum plate to obtain a diamond plate measuring 10 x 10 x 0.4 mm.

 PRI me R s 13-22 (Fig.24). Below are the results of attempts to synthesize diamond under different conditions.

 Comparative example 1.

 In the above example, no cooling gas was used.

Using a silicon (Si) wafer 5x5x0.2 mm in size as a substrate, after internal vacuumization of the vacuum chamber to 2 x 10 ^-3 Torr, hydrogen is supplied as a discharge gas at a rate of 20 L per 1 min under a pressure of 1 kg / cm ² , methane 40 ml / min at a pressure of 1 kg / cm ² is supplied between the electrodes to maintain the pressure in the vacuum chamber at the level of 100 torr. From a constant arc arc power supply, a current of 10A is supplied to the burner and maintained for 5 min until the voltage becomes constant. The voltage at this point was 65 V. The substrate holder 119 in FIG. 24 slowly approaches the burner 115, and the nozzle-substrate distance is set to 15 mm, the coating is deposited under these conditions for 1 h, and a good quality diamond coating with a thickness of 60 μm is obtained.

 In the above example, as a means for generating an active nonequilibrium plasma with a high concentration of radicals by abruptly cooling the thermal plasma, an example is given in which the cooling gas is encountered in the sprayed plasma, the sprayed gas from the four cooling gas injection outlets against the thermal plasma, but the cooling gas can be sprayed in the direction of the central axis of the plasma jet. It is also possible to inject cooling gas in only one direction toward the plasma jet to form a temperature distribution or a non-distribution of the concentration of radicals.

 According to the CVD method based on a plasma jet using direct current and cooling gas in accordance with the present invention, since thermal plasma can be cooled rapidly without regard to the substrate, compared to the CVD method based on a direct current plasma jet, diamond can be grown on any the substrate. Good-quality diamond can be grown with a high deposition rate of the coating of about 100 μm / h without cooling the substrate, which greatly extends the range of application of the diamond coating.

 This is a great advance towards the practical application of cheap diamond obtained by synthesis from the vapor phase, and the diamond synthesized in accordance with this method will have significantly reduced cost and improved performance when using a semiconductor circuit as a heat sink or substrate, and thus, a diamond heat sink or a substrate with a diamond circuit for a semiconductor can be easily implemented.

 PRI me R 23 and comparative example 2 (Fig.14).

 Using the devices shown in FIG. 13 (comparative example 2) and in FIG. 14, Example 23), a substrate of size 10x10x10.5 mm (thickness) is mounted on a holder of a substrate cooled by water, and the diamond coating is deposited on the substrate using a plasma torch, using tungsten as an electrode.

 In the device shown in FIG. 14, when a gas mixture of 20 L per 1 min of hydrogen gas and 0.2 L 1 min of methane gas is introduced to discharge, the discharge voltage has fluctuations of the order of 20 V at 90 V in the central value, and the plasma shape the jet changes significantly, but a 180-micron-thick diamond coating is formed as a result of deposition for 1 h. This coating shows a peak of only diamond when analyzed by X-ray diffraction and Raman spectroscopy.

 On the other hand, in the apparatus shown in FIG. 14, when hydrogen gas and methane gas were introduced separately into respective burners at a hydrogen speed of 20 l / min and 0.2 l / min methane to form a discharge, the discharge voltage of the burner for hydrogen was very stable order of 100 V ± 2 V, and the discharge voltage of the burner for methane was 20 V ± 2 V, and the shape of the plasma jet was constant, giving a uniform diamond coating with a coating layer thickness of about 150 μm.

 As described above, according to the present invention, since the hydrogen gas and the gaseous carbon compound as methane gas are supplied as separate plasma jets, the diamond coating can be formed in a very stable manner and also with high efficiency compared to the prior art, due to which the demand for the substrate may be satisfied. According to the present invention, heated filament, microwave discharge and (high-frequency) discharge can also be used instead of a direct current arc discharge.

 PRI me R 24 (Fig.19). On Fig and 24 schematically shows the device for the CVD method based on a plasma jet, used to implement the method according to the present invention. It has a plasma torch 115, a discharge gas supply pipe 116, an arc discharge power supply 114, a torch water cooling pipe 118, a substrate holder 119, a diamond substrate 120, a vacuum chamber 121, an exhaust system 122, a torch manipulator 123, a flow meter 124, gas bomb 125, feed pipe 126 of the source gas, the manipulator of the substrate 127.

 The plasma torch 115 has a water cooling device made of tungsten with the addition of 2 weight to it. yttrium oxide, together with the anode and cathode. The position and direction of the plasma torch 115 and the substrate holder 119 can be controlled by manipulators 123, 127 and can be moved relative to the plasma jet and the substrate, whereby the diamond coating can be grown uniformly even on a substrate with a large area or on a material with a complex surface shape. Although not shown in this schematic drawing, a heater for heating the substrate or a water-cooling device may also be mounted to control the temperature of the substrate.

Using a type IIa artificial diamond substrate of size 2x2x0.5 mm, after vacuuming the chamber to a level of 2x10 ^-3 torr, the pressure in the chamber is maintained at 120 torr due to the supply of hydrogen as a discharge gas at a speed of 20 l / min at a pressure of 1 kg / cm ² and methane as a source gas at a rate of 0.1 l / min at a pressure of 1 kg / cm ² .

 A current of 10 A is supplied from the DC arc source to the burner and maintained for 5 minutes until the voltage becomes constant. At this moment, the voltage is 50 V. When the substrate is slowly brought closer to the burner, the nozzle-substrate distance is set to 15 mm, and the coating is formed in this state for 1 h.

 When the obtained diamond was evaluated by Raman spectroscopy and a change in hardness, only a peak of diamond was detected in Raman spectroscopy, and the Vickers hardness had a value equal to natural diamond, which was about 10,000 at a load of 500 g. The thickness of the diamond coating was about 150 microns, and the coating formation rate was 150 μm / h.

 According to Lau X-ray diffraction and low energy electron diffraction (LEED), it was also confirmed that a single crystal diamond coating was epitaxially grown on a diamond base substrate.

Fluctuation in the discharge voltage was about 10% in this example. Thus, the stability of the arc discharge was also improved compared with the stability of the arc discharge according to the method of the prior art, which was about 20%
Further, in this example, graphite formation was not detected.

Example 25. Then, by mixing 0.1 ml / min of B ₂ H ₆ as a donor gas with the source gas under the conditions of coating formation of Example 24 and with a duration of coating formation of 10 minutes, a P-type semiconductor diamond having resistivity 10 ^-2 Ohmx xcm.

PRI me R 26. Using a silicon wafer of size 5x5x0.2 mm as a substrate, after the chamber has been evacuated to a level of 2x10 ^-3 Torr, the pressure in the chamber is maintained at 100 Torr by supplying hydrogen as a discharge gas at a rate of 20 l / min at a pressure of 1 kg / cm ² and methane so the source gas at a speed of 0.5 l / min at a pressure of 1 kg / cm ² .

 A current of 20 A is supplied from the DC arc source to the burner and is maintained for 5 minutes until the voltage becomes constant. The voltage at this moment is 50 V. The substrate slowly approaches the burner until the nozzle-substrate distance of 20 mm is established, and the coating is formed under these conditions for 1 h.

 The resulting diamond is evaluated by x-ray diffraction, Raman spectroscopy and hardness measurement. As a result, only a peak of diamond was detected based on X-ray diffraction and Raman spectroscopy, and the Vickers hardness was equal to natural diamond, which was about 10,000 at a load of 500 g. The thickness of the diamond coating was about 200 μm, and the deposition rate of the coating was 200 μm / h

 When the surface roughness of the synthesized diamond coating was measured and turned out to be about 10 μm, which is significantly better than 50 μm when the source gas is supplied as part of the discharge gas.

 The voltage fluctuations and the arc discharge voltage during diamond synthesis were determined at about 10% in this example, in which the arc discharge stability was also improved compared to about 20% in the prior art method. Further, in this example, graphite formation in the surrounding portion of the substrate was not detected.

 PRI me R 27. A molybdenum plate of size 5x5x0.5 mm is used as a substrate, methane is supplied as a source gas at a rate of 0.2 l / min, a current of 10 A DC and a DC voltage of 90 V are supplied to the anode and cathode electrodes under the conditions of example 26 coating formation. Similar results were obtained.

 With respect to the shape of the plasma injection device, FIG. 19 shows a sectional view, but the cathode 103 and the anode 104 can be arranged concentrically, and the cathode 103 source gas injection outlet and the nozzle 106 can be multifaceted (rectangular, etc.) or ellipsoidal provided that the discharge characteristics are not uniform. If necessary, it is also possible to form a heat-resistant insulating material in the form of comb teeth on the electrode, which will not affect the discharge. Then it is beneficial to cover a large area.

 Instead of diamond, quartz glass, tungsten, molybdenum, etc. can be used as a substrate for growing a coating without surface treatment.

 As a discharge atmosphere, use under reduced pressure is preferred, which ensures discharge stability, but use at atmospheric pressure or at high pressure is also possible. In the above example, an example of growing a diamond coating is provided, but the method is also applicable to the synthesis of diamond powder.

 The plasma jet injection device according to the invention can also be used for plasma spraying of a high-temperature superconducting oxide, such as a Ba-Y-Cu-O system, etc. as described above.

 When a diamond coating is grown by means of a device in accordance with the improved CVD method using a direct current plasma jet according to the invention, a good quality diamond coating with excellent surface evenness can be synthesized at a fast deposition rate of the coating of about 200 μm / h, so that the range of application of the diamond coating can be greatly expanded. By carrying out epitaxial growth of diamond according to the CVD method using a direct current plasma jet, an epitaxial coating of such thickness as 150 μm can be obtained at an extremely high coating formation rate of 150 μm / h.

 A diamond heat absorber or a diamond circuit on a substrate for semiconductor devices can be easily implemented, and finally a semiconductor diamond can be synthesized. The method is also applicable for plasma spraying of an inorganic compound such as heat resistant superconducting oxide.

Claims (20)

 1. The method of applying a diamond coating from the vapor phase, including the supply of a plasma-forming gas containing hydrogen to the area of the discharge electrodes, the initiation of the discharge, the generation of plasma, plasma-forming gas, the supply of a gaseous carbon compound into the produced plasma jet, hydrogen dissociation, radicalization of the carbon compound and coating deposition characterized in that, in order to expand technological capabilities by increasing the deposition rate and obtaining uniform films of sufficient thickness, arc is excited A new direct current discharge and a radicalized plasma jet are sharply cooled on the surface of the condensation.  2. The method according to claim 1, characterized in that after the excitation of the arc discharge, the radicalized plasma jet is blown into the volume under reduced pressure.  3. The method according to claims 1 and 2, characterized in that as a gaseous carbon compound, a hydrocarbon or a mixture of a hydrocarbon with oxygen, nitrogen or halogen is used.  4. The method according to claims 1 and 2, characterized in that the gas mixture comprising hydrogen and a gaseous carbon compound further comprises an inert gas, an oxidizing gas, or a mixture thereof.  5. The method according to claim 4, characterized in that oxygen, water, hydrogen peroxide or carbon monoxide are used as the oxidizing gas.  6. The method according to claims 1 and 2, characterized in that the cooling of the plasma jet is carried out by blowing a cooling gas into the plasma jet with the formation of a nonequilibrium plasma.  7. The method according to claim 6, characterized in that hydrogen contains in a plasma-forming, cooling, or in both gases.  8. The method according to claim 6, characterized in that the gaseous carbon compound is contained in a plasma-forming, cooling, or both gases.  9. The method according to claim 6, characterized in that the inert gas is contained in a plasma-forming, cooling, or both gases.  10. The method according to claim 6, characterized in that the oxidizing gas is contained in a plasma-forming, cooling, or both of these gases.  11. The method according to claim 1, characterized in that it includes the use of at least two plasma jets formed in tears with high and low discharge voltages, moreover, hydrogen is supplied to the discharge electrodes with a high discharge voltage, and in the discharge with a low discharge voltage a reactive gaseous carbon compound is formed.  12. The method according to claim 1, characterized in that it includes the use of many plasma jets with the possibility of their collision.  13. The method according to PP.1 and 2, characterized in that the Central part of the initial portion of the plasma jet serves a gaseous compound containing carbon, without passing it through the arc discharge zone.  14. The method according to item 13, wherein the plasma-forming gas contains at least one gas selected from the group consisting of hydrogen, an inert gas and an oxidizing gas.  15. The method according to item 13, wherein the plasma-forming gas contains a small amount of boron hydride, nitrogen or phosphorus.  16. The method according to claims 1 and 2, characterized in that the coating is grown epitaxially on a diamond substrate.  17. A device for applying a diamond coating from the vapor phase, containing discharge electrodes forming a nozzle, a plasma gas supply system, a substrate holder and power sources, characterized in that it is equipped with a direct current plasma torch and a cooling gas supply system in the form of nozzles located near the nozzle a plasma torch, and the discharge electrodes are made in the form of elements, one of which forms a discharge electrode with a closed housing in the form of a nozzle, and the other electrode of the opposite polarity and n opposite the nozzle.  18. The device according to 17, characterized in that the discharge electrodes are made of carbon material and tungsten containing rare earth oxide.  19. The device according to 17, characterized in that the plasma torch is made in the form of an external electrode forming a closed housing, and an internal electrode located in the housing and electrically isolated, the external electrode being provided with a gas supply hole and an injection nozzle, the side wall of the end section the inner electrode is located near the side of the injection nozzle of the outer electrode, and the gas supply hole is placed along the central axis of the inner electrode.  20. The device according to 17, characterized in that the plasma torch contains many nozzles, the inner walls of which form electrodes of the same polarity, and many electrodes of opposite polarity, placed in a closed case opposite the inner walls of the respective nozzles.

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