WO1998040533A1

WO1998040533A1 - Device and method for surface treatment

Info

Publication number: WO1998040533A1
Application number: PCT/JP1998/001068
Authority: WO
Inventors: Masamitsu Kitahashi
Original assignee: Komatsu Ltd.
Priority date: 1997-03-13
Filing date: 1998-03-13
Publication date: 1998-09-17

Abstract

A surface-treating device which generates radicals by exciting a gaseous starting material and brings the generated radicals into contact with the surface of a substrate is provided with a means which mixes the gaseous starting material by turning the material, a means which makes arc discharge by turning an energy transmitting gas, or a means which generates unbalanced plasma in an expansion nozzle. It is preferable to fix an electrode to an electrode holder by forming a groove on the periphery of the electrode and a tapered surface of 55° to 65°. It is more preferable to selectively use an electrode material having low reactivity to the gaseous starting material in accordance with the kind of the used gaseous starting material.

Description

Description Surface treatment equipment and surface treatment method

The present invention relates to a surface treatment apparatus, and more particularly to a surface treatment apparatus that efficiently excites a raw material gas to form radicals having high activity, and makes the radicals contact the substrate surface to perform a surface treatment of the substrate. Background art

As a gas phase excitation method in a conventional surface treatment apparatus,

(1) High frequency excitation method to excite source gas using high frequency

(2) Microwave excitation method that excites source gas using microwaves

(3) Electron beam irradiation method to excite source gas by irradiating source gas with electron beam

(4) Thermal filament method in which raw material gas is supplied to the hot filament and thermally excited

(5) The DC arc jet method using the DC arc jet is adopted. Of the above-mentioned methods, for applications requiring very high activity to the raw material gas, for example, for the vapor phase synthesis of diamond films, Japanese Patent Publication No. 4-77710, Japanese Patent Application Laid-open No. The DC arc jet method as disclosed in Japanese Patent Publication No. 92 is adopted. As shown in FIG. 10, the gas-phase synthesis method disclosed in Japanese Patent Publication No. Hei 4-77770 discloses that a hydrogen and gaseous carbonized compound is added to a plasma generator having an anode 2 and a cathode 1. Is supplied, and the gas is radialized by a DC arc discharge between the electrodes to form a thermal plasma, which is jetted into the raw material chamber 1 as a thermal plasma jet 19, and the thermal plasma jet is cooled to a cooled substrate 2 The diamond film C is quenched by colliding with the substrate 2 to vapor-grow the diamond film C on the substrate 22.

Further, as shown in FIG. 11, the gas phase synthesis method described in Japanese Patent Application Laid-Open No. 11-100092 supplies a gas to a plasma generator having an anode 2 and a cathode 1, This gas is radicalized by a direct current arc discharge between the electrodes to form thermal plasma, which is generated The heated thermal plasma is ejected from the nozzle at the tip of the torch as a plasma jet 19, and a raw material gas is sprayed on the ejected plasma jet 19 to generate a non-equilibrium plasma. Then, a diamond film C is vapor-phase grown on the substrate 22.

According to each of the above-mentioned DC arc jet methods, radicals having high energy can be generated, so that they exhibit a high growth rate even in vapor-phase growth requiring high energy such as diamond film formation, and have high productivity. Obtainable.

Furthermore, in the latter technology, the raw material gas is sprayed onto the plasma jet to rapidly cool the plasma jet, and the thermal plasma is changed to a so-called non-equilibrium plasma state to improve productivity.

However, with the former technology, the raw material radicals can be converted into high-temperature thermal plasma of 10,000 degrees or more, which easily causes problems such as melting and destruction of the substrate. Furthermore, due to the characteristics of the DC plasma jet, a film can be formed only within the arc irradiation range, and thus there is a problem that the area where the film can be formed is small.

In addition, depending on the type of the source gas, the tungsten discharge electrode may be severely consumed. For example, when the source gas contains carbon atoms, tungsten carbide is generated, and when the source gas contains oxygen atoms, tungsten oxide is generated and the discharge electrode is consumed. Further, the tungsten compound generated in this way adheres to the substrate surface, which causes deterioration of the film quality.

For example, it was observed that the electrode was greatly consumed when a gas containing 0.8% CH ₄ was discharged for 2 hours under the following conditions.

NO Item Condition

1 Arc current Non-transfer type 15 [A]

2 Arc voltage 50 to 70 [V] (Varies greatly)

3 Reaction gas Ar: 6.5 [L / min]

H ₂ : 0.75 [L / min]

CH ₄ : 0.06 [L / min] These mixed gases

4 Force Sword Electrode Holder: Copper

Electrode: Tungsten with 2% thoria 5 Anode Material: Copper

Nozzle diameter: Φ 2.2 On the other hand, in the latter conventional technique, since the source gas does not come into contact with the discharge electrode, the problem of electrode consumption and mixing of the electrode material as described above does not occur, but the inert gas is used as the plasma gas. When using, the arc is likely to be unstable, so that the energy transmitted to the source gas varies, and this variation affects the film quality.

Furthermore, despite the fact that the plasma jet injected into the decompression chamber becomes a supersonic flow due to thermal expansion, the flow velocity of the raw material gas is low, so that the supersonic plasma jet and the raw material gas are separated. There is also a problem that mixing is not performed well, and energy transfer efficiency to the raw material gas and cooling efficiency of the plasma jet are reduced. Disclosure of the invention

An object of the present invention is to provide a surface treatment apparatus effective for improving the excitation efficiency of a gas phase.

To achieve the above object, the invention described in claim 1 is

In a surface treatment device that excites the source gas to form radicals, and the generated radicals contact the substrate surface,

Source gas supply means for supplying the source gas,

Energy transmission gas supply means for supplying an energy transmission gas serving as an energy transmission medium for exciting the source gas,

Thermal plasma generating means for converting the energy transfer gas supplied by the energy transfer gas supply means into thermal plasma;

A material radical generating means for mixing the thermal plasma generated by the thermal plasma generating means with the raw material gas supplied by the raw material gas supply means to generate a raw material radical;

The source gas supply means,

Equipped with source gas swirling means for swirling the source gas to be supplied It is characterized by the following.

Here, the source gas supply means applies pressure to a gas phase containing a substance to be brought into contact with the substrate surface, causes the gas phase to flow through a flow path having a predetermined shape, and sends the gas to an excitation point of the source gas. The raw material gas, for example, in the case of forming a diamond film on the substrate surface, using a carbon compound, in the case of forming an C -BN is a reactive gas such as NH 3 gas and B ₂ H _s gas use. In addition, use a reactive gas corresponding to various surface treatments such as etching, oxidation, and nitriding.

The energy transfer gas supply means applies pressure to a gaseous phase serving as a carrier of excitation energy, flows the gaseous phase into a flow path having a predetermined shape, and sends the gaseous phase to a point for thermal plasma conversion.

The thermal plasma generating means is a means for rapidly heating an energy transfer gas to generate thermal plasma, and applies ignition, arc discharge, high frequency excitation, microwave excitation, electron beam excitation, hot filament excitation, and the like.

The raw material radical generating means mixes the energy transfer gas converted into the thermal plasma with the raw material gas, sends the energy filled in the energy transfer gas to the raw material gas, and radicalizes the raw material gas. As a space for mixing the two, use a space that suppresses the expansion of the gas phase, such as a reduced nozzle whose opening cross section gradually decreases toward the downstream of the flow path or a cylindrical nozzle whose opening cross section is constant and elongated. It is preferable.

The raw material gas swirling means is a means for rotating the raw material gas by adding a rotational component to the flow direction of the raw material gas. An additional configuration or a stirring means using a rotary blade is applied.

By providing the raw material gas swirling means, the raw material gas and the energy transfer gas converted into thermal plasma are smoothly mixed, and the energy transfer efficiency can be improved.

The invention described in claim 2 is the invention according to claim 1,

The energy transfer gas supply means,

Equipped with an energy transfer gas swirling means for swirling the supplied energy transfer gas Do

It is characterized by the following.

This energy transfer gas swirl means swirls the energy transfer gas by the same means as the above-described source gas swirl means.

As described above, by providing the energy transfer gas swirling means, the energy transfer gas is supplied to the thermal plasma generation means in a swirled state. A stable discharge state can be obtained by the pressure gradient formed by the turning. Therefore, an inert gas such as argon can be stably used as the energy transfer gas.

The invention according to claim 3 is the invention according to claim 1 or claim 2, wherein the non-equilibrium plasma generation means for generating a non-equilibrium plasma by adiabatically expanding the source radical generated by the source radical generation means. Furthermore

It is characterized by the following.

The non-equilibrium plasma generating means adiabatically expands the raw material radicals, increases the flow rate of the raw material radicals, and configures a wide area spray width. The term “insulation” as used herein includes not only a completely insulated state, but also a state in which heat flow is extremely low. As the non-equilibrium plasma generating means, an enlarged nozzle whose opening section gradually increases toward the downstream of the flow path, and a nozzle having an opening cross section wider than the flow path of the raw material radical are used.

Here, in general, when the material radicals are adiabatically expanded, the particle density decreases toward the outer periphery of the expanded gas flow, and when the particle density of the ejected material radicals becomes non-uniform, so-called dissipation is performed. The effect occurs.

Therefore, in the present invention, in order to improve the uniformity of the source radical, a source gas swirling means is provided to swirl the source gas. That is, the raw material gas swirled by the raw material swirling means is radicalized while being swirled by the raw material radical generating means. The gas flow becomes high. As a result, the above-mentioned dissipative effect is complemented, and a raw material radical stream having a uniform particle density can be ejected. The invention described in claim 4 is the invention according to any one of claims 1 to 3,

The source gas swirling means,

An annular source gas circuit surrounding the thermal plasma flow generated by the thermal plasma generating means;

A source gas introduction passage disposed at a periphery of the source gas circulation circuit, for introducing the source gas supplied by the source gas supply unit in a direction deviated from the center of the source gas circulation circuit.

It is characterized by the following.

The source gas circuit is an annular flow path arranged so as to surround the thermal plasma generated by the thermal plasma generating means. The source gas introduction path is a flow path for introducing the source gas from the outer periphery of the source gas wire circuit, and the source gas introduced from the source gas introduction path is separated from the center of the source gas rotation circuit by thermal plasma. Mix into the stream. Here, preferably, a plurality of the source gas introduction paths are arranged on the outer peripheral tangent of the source gas rotation circuit, and the source gas introduction paths are introduced so that the rotation directions of the source gases introduced from the respective source gas introduction paths are the same. Unify the directions.

In addition, the invention described in claim 5 is the invention according to any one of claims 1 to 4,

The thermal plasma generating means,

A flow path for the energy transfer gas,

A force sword and an anode disposed in the flow path;

An insulating member surrounding the periphery of the cathode with the tip of the force sword being exposed.

It is characterized by the following.

Here, the force source and the anode are used as discharge electrodes, and are arranged close to each other. The insulating member surrounding the periphery of the cathode is interposed to maintain the insulated property between the cathode and the anode, and is preferably configured to conform to the shape of the force source. For example, if the force sword is cylindrical For example, a cylindrical shape is used for the insulating member. This insulating member is disposed between the power source and the anode with the discharge point of the power source exposed. It is preferable that the source gas swirling means is provided at a tip of the insulating member.

As described above, since the discharge point is defined by surrounding the periphery of the force sword with the insulating member, the discharge is stabilized.

The invention described in claim 6 is the invention according to claim 5,

The energy transfer gas swirl means,

An annular energy transfer gas swirling circuit surrounding the tip of the force sword;

An energy transfer gas introduction path, which is provided at a periphery of the energy transfer gas swirling circuit and that introduces the energy transfer gas supplied by the energy transfer gas supply unit in a direction deviated from the center of the energy transfer gas swirl path. Have

It is characterized by the following.

The energy transfer gas swirl circuit is an annular flow path arranged so as to surround a tip (preferably, a discharge point) of a force source. The energy transfer gas introduction path is a flow path for introducing the energy transfer gas into the energy transfer gas circuit. The energy transfer gas introduced from the energy transfer gas introduction path collides with the inner wall of the energy transfer gas swirl circuit, avoiding the center of the energy transfer gas swirl circuit, and turns along the inner wall. The energy transfer gas swirled in this manner forms a pressure gradient near the tip of the force sword, stabilizing the discharge.

The invention according to claim 7 is the invention according to claim 5 or claim 6, wherein the force sword is:

An electrode made of a high melting point metal with a groove formed on the periphery,

An electrode holder having a concave portion at the tip and holding the electrode in the concave portion is provided.

Here, the electrode is a portion serving as a discharge point, and is formed of a high melting point metal such as tungsten. One or more grooves are formed on the periphery of this electrode. Further, the electrode holder has a concave portion for holding the electrode, and the electrode is held in a state fitted in the concave portion. This recess has a protrusion that fits into the groove formed in the electrode. It is desirable that the raised portion be formed or filled with a brazing material to enhance the fitting property with the electrode.

When the electrode is inserted into the recess, a part of the recess enters a groove formed in the electrode due to plastic deformation of the recess, and the electrode expands due to a difference in the coefficient of thermal expansion between the electrode and the electrode holder. Even if a gap is formed between the electrode and the concave portion, the portion that enters the groove prevents the electrode from falling.

Further, even when the electrode is fixed by brazing, the brazing material filled in the recess enters the groove formed in the electrode, so that a gap is generated due to the difference in the coefficient of thermal expansion as described above. Even in this case, the material that has entered the groove prevents the electrode from falling.

The invention described in claim 8 is the invention according to claim 7,

The electrode is

A flat tip surface,

Having a recess formed at the center of the tip surface

It is characterized by the following.

The arc is stabilized by the concave portion formed at the center of the tip surface, and the fluctuation of the arc generating voltage is prevented. As a result, the surface of the substrate treated according to the present invention becomes stable, and it is possible to prevent the electrode material from being mixed into the treated surface due to the consumption of the electrode.

The invention according to claim 9 is

Source gas supply means for supplying the source gas,

The thermal plasma generated by the thermal plasma generating means is supplied by the raw gas supply means. A raw material radical generating means for mixing the raw material gas with the raw material gas to generate a raw material radical,

The energy transfer gas supply means,

Equipped with energy transfer gas swirl means for swirling the energy transfer gas to be supplied

It is characterized by the following.

The invention according to claim 10 is

Source gas supply means for supplying the source gas,

A mixing space for mixing the thermal plasma generated by the thermal plasma generating means with the raw material gas supplied by the raw gas supply means,

An expansion nozzle connected downstream of the mixing space and adiabatically expanding the mixed gas mixed in the mixing space.

It is characterized by the following.

The enlarged nozzle constitutes a supersonic nozzle, and a gas flow passing through the supersonic nozzle is jetted at a flow velocity higher than the sonic velocity. As a result, the raw material radicals reach the substrate surface in a short time while maintaining a high reaction state, so that the adhesion of the raw materials and the processing speed are improved. In addition, the temperature of the raw material radicals that have passed through the expansion nozzle is reduced by adiabatic expansion, so that deterioration of the substrate surface is suppressed.

The invention described in claim 11 is

An electrode made of a high melting point metal with a groove formed on the periphery, An electrode holder having a concave portion at the tip and holding the electrode via a brazing filler material filled in the concave portion.

It is characterized by the following.

The invention of claim 12 is the invention of claim 11,

The electrode is

It has a tapered part whose diameter is reduced from 55 ° to 65 °.

It is characterized by the following.

As described above, by providing the 55 ° to 65 ° taper portion on the electrode, the arc generation voltage can be further stabilized.

The invention described in claim 13 is the invention according to claim 11 or claim 12,

The electrode is

A flat tip surface,

Having a recess formed at the center of the tip surface

It is characterized by the following.

The invention described in claim 14 is the invention according to any one of claims 11 to 13,

The electrode holder,

It is characterized by being composed mainly of any one of copper, silver, aluminum, brass, molybdenum, tungsten, niobium, tantalum, and copper, or an alloy of two or more thereof.

Since the electrode holder made of the above metal suppresses the consumption of the electrode material, a stable arc discharge can be obtained for a long time, and the electrode material is prevented from being mixed into the treated surface.

The invention described in claim 15 is the invention according to any one of claims 11 to 14,

The electrode is

Tungsten, calcium oxide, thorium oxide, yttrium oxide, zirconium The main component is an alloy consisting of at least one of palladium and hafnium or two or more of them

It is characterized.

Since the electrode made of the above-mentioned metal suppresses the consumption of the electrode material, a stable arc discharge can be obtained for a long time, and the electrode material is prevented from being mixed into the treated surface. In particular, an electrode containing zirconium or hafnium has a remarkable effect of suppressing consumption when exciting a gas phase containing oxygen atoms. The invention described in claim 16 is the invention according to any one of claims 11 to 15,

The electrode is

Contained by mixing at least one of lanthanum, thorium, strontium, cerium, yttrium or their oxides

It is characterized by the following.

The electrode mixed with the metal suppresses consumption of the electrode material.

The invention described in claim 17 is

An electrode made of a high melting point metal,

An electrode holder having a concave portion at the tip and holding the electrode via a brazing filler material filled in the concave portion,

The electrode is

A flat tip surface,

Having a recess formed at the center of the tip surface

It is characterized by the following.

The invention of claim 18 is

In a surface treatment method for treating a substrate surface by exciting a source gas to form radicals and injecting the generated radicals onto the substrate surface,

An energy transfer gas serving as a transfer medium of energy for exciting the source gas, The raw material gas is mixed while swirling to generate a raw material radical that flows out while swirling,

The raw material radical is adiabatically expanded, and is sprayed on the substrate surface while rotating the raw material radical.

It is characterized by the following.

By mixing the raw material gas into the energy transfer gas while swirling as described above, the two are mixed smoothly, and the generated raw material radicals are also given a swirl component. It becomes denser toward the outer circumference of the swirling flow, complementing the dissipation effect during adiabatic expansion.

The invention of claim 19 is the invention of claim 18, wherein

The energy transfer gas is swirled in the same direction as the swirling direction of the source gas to mix the energy transfer gas and the source gas.

It is characterized by the following.

In this way, by swirling both the energy transfer gas and the source gas in the same direction, the mixing of the two can be performed smoothly and the swirling component of the generated raw material radical becomes stronger, so that the dissipative effect is reduced. The complementing effect is further enhanced. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a cross-sectional view showing one configuration example of a surface treatment apparatus according to the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a vapor phase growth apparatus provided with a surface treatment apparatus according to the present invention.

FIG. 3 is a cross-sectional view showing one configuration example of the thermal plasma generating means.

FIG. 4 is a cross-sectional view showing one configuration example of the raw material radical generating means.

FIG. 5 is a diagram showing a Raman spectrum of a diamond film produced according to the present invention.

FIG. 6 is a sectional view showing a second configuration of the force sword 1. As shown in FIG.

FIG. 7 is a conceptual diagram showing the configuration of an experimental apparatus used for determining the tip angle of the tungsten electrode rod 102. FIG. 8 is a view showing an inclination angle of a tapered surface used in the experimental apparatus shown in FIG. FIG. 9 is a sectional view showing a third configuration of the force sword 1.

FIG. 10 is a sectional view showing a conventional DC arc jet method.

FIG. 11 is a sectional view showing a conventional DC arc jet method. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing one configuration example of a surface treatment apparatus according to the present invention. First, a schematic configuration of a surface treatment apparatus according to the present invention will be described with reference to FIG.

The surface treatment apparatus shown in the figure is provided with a thermal plasma generating means for converting an energy transfer gas into a thermal plasma. In this embodiment, argon gas is used as the energy transfer gas.

The thermal plasma generating means is provided with a force source 1 and an anode 3 for generating an arc discharge, and the anode 3 is disposed so as to surround the power source 1 via a ceramic shield tube 2. You. The shield cylinder 2 defines a discharge point that exposes the tip of the force sword 1 to generate an arc discharge.

Downstream of the thermal plasma generating means, there is provided a raw material radical generating means for reacting the raw material gas with the thermal plasma to excite it to generate a raw material radical. In this embodiment, a mixed gas of CH ₄ and H ₂ is used as a source gas.

A non-equilibrium plasma generating means is provided downstream of the raw material radical generating means for converting the thermal radicalized raw material radical into non-equilibrium plasma by adiabatic expansion. The non-equilibrium plasma generating means mainly includes an enlarged nozzle 5.

The surface treatment apparatus configured as described above is used as a source plasma jetting means of a vapor phase growth apparatus as shown in FIG. Here, FIG. 2 is a cross-sectional view showing a configuration of a vapor phase growth apparatus provided with the surface treatment apparatus according to the present invention. The vapor phase growth apparatus shown in the figure grows a diamond thin film on the surface of a substrate 22 made of glass.

Next, a configuration example of the thermal plasma generating means will be described in detail with reference to FIG. number 3 The figure is a cross-sectional view showing one configuration example of the thermal plasma generating means.

As shown in FIG. 1A, in this thermal plasma generating means, an electrode rod 102 made of tungsten is fixed to a body 101 made of copper by brazing. The inside of the cathode is hollow, and a cooling water introduction space 103 is formed. The cooling water is introduced from the first nipple 8 shown in FIG. 1, passes through the cooling water introduction pipe 104, is guided to the cooling water introduction space 103, cools the power sword 1, and cools the water. The cooling water is discharged from the second nipple 9 through the cooling water discharge space 105 outside the pipe 104. Further, a heat-resistant ceramic insulating cylinder 2 is formed around the force sword 1 so as to cover the tip, and an anode 3 is disposed outside the insulating cylinder 2. In addition, a first swirler 201 for blowing the energy transfer gas into the discharge space 17 while turning the energy transfer gas is provided at the tip of the insulating cylinder 2 as shown in FIG. 3 (b). Here, FIG. 3 (b) is a diagram showing an AA cross section of FIG. 3 (a).

As shown in the figure, the first swirler 201 has four energy gas inlets 210 for introducing an energy transfer gas, and an energy gas swirling circuit for swirling the energy transfer gas introduced from the inlet. It consists of 2 1 2. Here, the energy transmission gas introduction port 210 is disposed at a position deviated from the center of the energy gas rotation circuit 212.

The energy transfer gas introduced from the third nipple 6 passes through the insulating cylinder 2 and the gap 202 between the anode 3 and forms a vortex in the first swirler 201 configured as described above. To the discharge space 17. Further, the anode 3 is provided with a plasma jet outlet 301 and a cooling water introduction space 302, and cooling water is introduced from the fourth nipple 11 and is cooled in the cooling water introduction space 302. After cooling the anode 3, it is discharged from a fifth nipple (not shown).

As shown in FIG. 2, the surface treatment apparatus shown in this embodiment is provided with a DC power supply 13 in which the negative electrode side is connected to the first nipple 8 and the positive electrode side is connected to the third nipple 6. The current supplied from the DC power supply 13 is supplied from the third nipple 6 to the cover 15, cap 14, divergent nozzle 5, anode 3, arc 16, power source 1, conductive cylinder 106, Takes a current path called nipple 8. Next, a configuration example of the raw material radical generating means will be described in detail with reference to FIG. FIG. 4 is a cross-sectional view showing one configuration example of the raw material radical generating means.

The raw material radical generating means is a conical raw material generating space as shown in FIG. 3A, and is provided downstream of the plasma jet outlet 301 as shown in FIG. Two swirlers 4 0 1 are provided. Here, FIG. 4 (b) is a diagram showing a BB cross section of FIG. 4 (a).

The plasma jet outlet 301 forms a flow path of thermal plasma extending in a constant cross section as shown in FIG. 3A, and rectifies the thermal plasma passing through the flow path. The second swirler 401 has four source gas inlets 410 for introducing a source gas and a source gas swirler for swirling the source gas introduced from the inlet, as shown in FIG. Road 4 1 2 Here, the source gas inlet 4 10 is disposed at a position deviated from the center of the source gas circuit 4 12. The raw material gas introduction port 410 is formed, for example, by a linear flow path having a hole diameter of 2 mm, and is provided from the central axis direction of the nozzle to the tangential direction of the inner wall of the nozzle.

With the above configuration, the raw material gas introduced from the sixth nipple 7 shown in FIG. 1 passes through the space 10, passes through the raw material gas inlet 4 12 shown in FIG. The gas is injected in the circumferential direction of the gas spiral circuit to form a swirling flow along the circumference, and is injected into the raw material radical generation space 4 shown in FIG.

The swirling flow of the ejected source gas collides with and mixes with the thermal plasma ejected from the plasma jet outlet 301, and the energy of the thermal plasma is transmitted to the source gas. As a result, the source gas to which the energy has been transferred becomes high-activity and high-density source radicals in the form of thermal plasma.

Then, the raw material radicals are ejected to an expansion nozzle configured as a non-equilibrium plasma generating means, and are adiabatically expanded while passing through the expansion nozzle to be converted into a low-temperature non-equilibrium plasma while maintaining high activity. Is done.

The enlarged nozzle 5 is a medium-sized nozzle, and is formed such that the opening cross section gradually increases toward the downstream of the flow path.

The non-equilibrium plasma generated as described above is applied to the substrate 2 as shown in Fig. 2. It is sprayed on the surface of 2 to grow a film on the surface.

Here, the vapor phase epitaxy apparatus shown in FIG. 2 will be briefly described. In this vapor phase epitaxy apparatus, a heater 21 is provided in a decompression chamber 120, and a substrate 22 is used as a substrate heater. Fixed on one. The substrate heater 21 can perform both substrate heating and substrate cooling, so that the temperature of the substrate 22 can always be maintained at an appropriate temperature. The substrate heater 21 is fixed to an elevating mechanism (not shown) via a bellows 27, and the non-equilibrium plasma jet 501 and the distance 24 to the substrate can be set arbitrarily within a certain range. It is configured to be able to.

The following table shows the film forming conditions and the shape of the enlarged nozzle when performing vapor phase growth using the vapor phase growth apparatus configured as described above.

As a result of forming a film in this manner, a polycrystalline diamond film was formed on the substrate. The particle diameter was about 0.1 m to 5 Aim, and the film formation rate was about 500 [m / h], and a very high film formation rate could be realized. Figure 5 shows the Raman spectrum at this time. As shown in the figure, the thin film on the substrate treated according to the present invention becomes an extremely high quality diamond thin film with few impurities. Further, according to the present invention, a thin film having a diameter of about 50 mm can be grown, and the area can be increased as compared with the related art. Next, a second configuration example of the thermal plasma generating means will be described with reference to FIG.

FIG. 6 is a sectional view showing a second configuration of the force sword 1. As shown in FIG. As shown in the figure, the force source 1 according to the second configuration has a recess 23 formed in a copper electrode holder 101, and a brazing material 25 mainly composed of silver is formed in the recess 23. The electrode 28 is provided with a groove 28 having a depth of about 0.5 mm and a tungsten electrode rod 102 obtained by mixing about 2% of thorium. The tungsten electrode rod 102 is formed with a tapered surface 30 having a tip angle of 55 ° to 65 °, and a flat surface 29 formed at the foremost end thereof. A hole 26 is formed at the center of. Here, the joint between the distal end surface 29 and the tapered surface 30 has a gentle shape.

When the tungsten electrode rod 102 configured as described above is swaged to the electrode holder 101, the electrode holder 101 is plastically deformed, enters the groove 28, and is fitted with the electrode rod 102. Combine. As a result, even if a gap is formed between the electrode and the electrode holder due to the difference in the coefficient of thermal expansion between the electrode material and the electrode holder material when an arc is generated, the part fitted with the groove 28 prevents the electrode from falling off. .

On the other hand, the tip angle of the tungsten electrode rod 102 was determined by the following experiment.

FIG. 7 is a conceptual diagram showing the configuration of an experimental apparatus used for determining the tip angle of the tungsten electrode rod 102. As shown in the figure, in this experimental apparatus, a nozzle anode 32 is provided so as to surround the cathode 1, and a water-cooled copper anode 33 is provided outside the nozzle anode 32 at a predetermined interval. It was established. Then, the insulation between the force sword 1 and the nozzle anode 32 is broken down by the high-frequency power supply 36, and then the arc between the force sword 1 and the nozzle anode 32 is generated by the power of the non-transferable DC power supply 34. As soon as this arc current is detected by the ammeter 38, the non-transitional DC power supply 34 is turned off, and instead the transitional DC power supply 35 is turned on, and the power source 1 and the water-cooled copper anode 3 are turned on. An arc is generated between three. At this time, the switching of the output from the non-transitional DC power supply 34 to the transitional DC power supply 35 is instantaneous, and the arc generated between the power source 31 and the nozzle anode 32 is unstable. No arc is ignited between force sword 1 and water-cooled copper anode 3 3 State, that is, an ignition error occurs.

Using the experimental apparatus configured as described above, as shown in FIG. 8, the inclination angle of the taper surface 30 was set to 75 °, 70 °, 65 °, 60 °, 55 °, 50 °, 45 °. The ignition frequency and the series arc frequency were measured for each inclination angle under the following conditions.

The results of the above experiment are shown below.

As is evident from the experimental results, when the angle of inclination was 55 ° to 65 °, no ignition error and no series arc occurred, so the angle in this range was selected as a preferable angle. As a result, a stable arc can be generated both when the arc is ignited and when the arc is continuously generated. In the above embodiment, the electrode holder was made of copper, and the electrode rod was made of tungsten mixed with about 2% of thorium. In addition, copper, silver, aluminum, and aluminum were used as electrode holders. It may be one containing brass, molybdenum, tungsten, niobium, tantalum, or copper, or an alloy containing at least two of them. Further, in addition to these, any of calcium oxide, thorium oxide, and yttrium oxide or an alloy thereof may be used. Further, at least one of lanthanum, trim, strontium, cerium, yttrium or an oxide thereof may be mixed with these materials. —

Further, using a CO or C_〇 ₂ as a material gas, If you want some H ₂ as the discharge gas to form a diamond thin film by using a A r, or CH ₄ used as the raw material gas, the 〇 ₂ used as the discharge gas When a material containing oxygen is used as a raw material or a discharge gas, such as when a diamond thin film is formed, it is preferable to use zirconium or hafnium or an alloy thereof. For example, a force sword as shown in FIG. 9 is provided, and the entire cathode electrode 101S made of hafnium is fixed via a brazing material 25 in the concave portion of the electrode holder 102 constituting the cathode. . Here, FIG. 9 is a sectional view showing a third configuration of the force sword 1. As shown in FIG.

With the above structure, when a material containing oxygen is used as a raw material or a discharge gas, hafnium oxide is formed on the surface of hafnium. Since hafnium oxide is a very stable substance as compared with hafnium, the melting point of the electrode is increased, and the consumption is reduced. Since hafnium has a lower thermal conductivity than tungsten, it is desirable to cover the whole with an electrode holder.

In the above embodiment, a groove is formed on the periphery of the electrode. However, a groove may be formed on the electrode holder and a protrusion corresponding to the groove may be formed on the electrode, or a protrusion may be formed on the electrode side. It may be.

Further, in the above-described embodiment, the description has been made for the DC use, but the present invention is also applicable to the AC use. Further, in the above embodiment, the non-equilibrium plasma generating section is constituted by the enlarged nozzle. However, the present invention is not limited to the enlarged nozzle, and may use a cylindrical nozzle or the like. In addition, an insulating cylinder is interposed between the force sword and the anode to define the discharge space. However, the present invention is applicable even when there is no insulating cylinder.

Further, in the embodiment, the shielding body is provided with a swirl flow generating means for swirling the source gas at the tip of an insulating cylinder disposed so as to surround the force source. It may be formed. Industrial applicability

By swirling the source gas and mixing it with the energy transfer gas, the transfer efficiency of heat energy is improved, and high activity and low temperature source radicals can be generated.

In addition, by providing an expansion nozzle, the raw material radicals are ejected to the decompression chamber as a supersonic plasma jet, so that the raw material radicals reach the substrate while maintaining high activity, and the film quality and the film forming speed are increased. Can be improved.

In addition, since the arc discharge is stabilized by swirling and supplying the energy transfer gas, an inert gas such as argon or helium can be used as the energy transfer gas. This makes it possible to suppress electrode wear and mixing of electrode materials.

Also, by providing a groove on the periphery of the electrode, the electrode can be prevented from falling.

In addition, by selecting the electrode material according to the type of gas, consumption of the electrode is suppressed, so that stable and highly reliable discharge and high quality film formation can be achieved.

Claims

The scope of the claims

1. In a surface treatment device that excites the source gas to form radicals and brings the generated radicals into contact with the substrate surface,

Source gas supply means for supplying the source gas,

A source radical generating unit configured to mix the thermal plasma generated by the thermal plasma generating unit with the source gas supplied by the source gas supplying unit to generate a source radical;

The source gas supply means,

Equipped with source gas swirling means for swirling the source gas to be supplied

A surface treatment apparatus characterized by the above-mentioned.

2. The energy transfer gas supply means includes:

2. The surface treatment apparatus according to claim 1, wherein:

3. It further comprises a non-equilibrium plasma generating means for adiabatically expanding the raw material radicals generated by the raw material radical generating means to generate non-equilibrium plasma.

3. The surface treatment apparatus according to claim 1, wherein:

4. The source gas swirling means is

An annular source gas circuit surrounding the thermal plasma flow generated by the thermal plasma generating means; A source gas introduction passage disposed at a peripheral edge of the source gas circuit, for introducing the source gas supplied by the source gas supply unit in a direction deviated from the center of the source gas circuit.

4. The surface treatment apparatus according to claim 1, wherein:

5. The thermal plasma generating means includes:

A flow path for the energy transfer gas,

A force sword and an anode disposed in the flow path;

An insulating member that surrounds the periphery of the cathode with the tip of the force sword being exposed.

5. The surface treatment apparatus according to claim 1, wherein:

6. The energy transfer gas swirl means is:

An annular energy transfer gas swirling circuit surrounding the tip of the force sword; and Means for introducing an energy transfer gas supplied by the means.

6. The surface treatment apparatus according to claim 5, wherein:

7. The power sword is

7. The surface treatment apparatus according to claim 5, further comprising an electrode holder having a concave portion at a tip and holding the electrode in the concave portion.

8. The electrode is

A flat tip surface,

Having a recess formed at the center of the tip surface

8. The surface treatment device according to claim 7, wherein:

9. In a surface treatment device that excites the source gas to form radicals and brings the generated radicals into contact with the substrate surface,

Source gas supply means for supplying the source gas,

The energy transfer gas supply means,

A surface treatment apparatus characterized by the above-mentioned.

10. In a surface treatment device that excites the source gas to form radicals and contacts the generated radicals with the substrate surface,

Source gas supply means for supplying the source gas,

A surface treatment apparatus characterized by the above-mentioned.

1 1. In a surface treatment device that excites the source gas to form radicals and brings the generated radicals into contact with the substrate surface.

A surface treatment apparatus, comprising: a concave portion at a tip, and an electrode holder that holds the electrode in the concave portion.

1 2. The electrode is

It has a taper part whose diameter is reduced from 55 ° to 65 °.

The surface treatment apparatus according to claim 11, wherein:

1 3. The electrode is

A flat tip surface,

Having a recess formed at the center of the tip surface

The surface treatment apparatus according to claim 11 or 12, wherein:

1 4. The electrode holder

Claims 11 to 11 characterized in that it is composed mainly of any one of copper, silver, aluminum, brass, molybdenum, tungsten, niobium, tantalum and copper or an alloy composed of two or more thereof. 13. The surface treatment apparatus according to any one of 13.

1 5. The electrode is

It is composed mainly of tungsten, calcium oxide, thorium oxide, yttrium oxide, zirconium, hafnium, or an alloy composed of two or more of them.

The surface treatment apparatus according to any one of claims 11 to 14, wherein:

1 6. The electrode is Contained by mixing at least one of lanthanum, thorium, strontium, cerium, yttrium or their oxides

The surface treatment apparatus according to any one of claims 11 to 15, wherein:

17. In a surface treatment device that excites the source gas to form radicals and contacts the generated radicals to the substrate surface,

An electrode made of a high melting point metal,

The electrode is

A flat tip surface,

Having a recess formed at the center of the tip surface

A surface treatment apparatus characterized by the above-mentioned.

18. A surface treatment method for treating a substrate surface by exciting a source gas to generate radicals and injecting the generated radicals onto the substrate surface.

The raw material gas is mixed into the energy transfer gas serving as a transmission medium of energy for exciting the raw material gas while swirling to generate raw material radicals flowing out while swirling,

A surface treatment method comprising:

1 9. The energy transfer gas is swirled in the same direction as the swirling direction of the source gas to mix the energy transfer gas and the source gas.

19. The surface treatment method according to claim 18, wherein: