JP6161053B2 - Vapor deposition source and fine particle forming device - Google Patents

Description

  The present invention relates to an evaporation source and a fine particle forming apparatus used in a wide range of technical fields such as the automobile industry, energy industry, home appliance industrial chemical industry, and the like that handle fuel cell catalysts, photocatalysts, exhaust gas catalysts, and the like.

Conventional catalysts used for fuel cell catalysts, photocatalysts, exhaust gas catalysts, etc. are made by a complex wet method in which a metal such as a precious metal is powdered, a molten salt is produced, and the slurry is used to carry a coating. Yes.
However, recently, a dry method in which nanoparticles are directly produced and supported on a substrate in a vacuum or low-pressure gas atmosphere using an arc plasma evaporation method has attracted attention. This method is an epoch-making method in which the process for producing and supporting the catalyst is extremely simple as compared with the conventional wet method.

When using the arc plasma evaporation method to produce nitride or carbonitride nanoparticles such as Nb, Ta, Ti, and Zr used for fuel cell catalysts, photocatalysts, exhaust gas catalysts, etc. Alternatively, a target is prepared with a rod of metal carbide, pulsed to generate these plasmas, and N ₂ gas is introduced from the chamber at the same time, and a nitride or carbon is formed on a powder substrate such as a plate substrate or carbon black. Nitride nanoparticles are being created. In this case, N2 gas was introduced from the chamber.

JP 2007-204810 A

However, it is difficult to avoid oxygen contamination in the compound nanoparticles and film by the conventional method described above.
In addition, it is difficult to avoid mixing oxygen even if the chamber is sufficiently baked and the powder of the substrate is heated or held in a vacuum to sufficiently dehydrate it. Therefore, these dielectric films (transparent and insulating) are generated, and there is a problem that the catalytic function may not be sufficiently exhibited.

  The present invention is for solving the above-described conventional problems, and an object thereof is to provide a vapor deposition source and a fine particle forming apparatus capable of suppressing oxidation of a target film and nanoparticles.

To solve the problems of the prior art described above, the evaporation source of the present invention in order to achieve the object described above, a cylindrical anode electrode, and a circle cylindrical cathode, a cylindrical trigger electrode, said cathode A vapor deposition material connected to an electrode; and an insulator disposed between the vapor deposition material and the trigger electrode. The vapor deposition material is disposed at a position close to the trigger electrode, and is disposed on the trigger electrode. When a voltage is applied, electrons due to trigger discharge are generated between the trigger electrode and the vapor deposition material, and the electron triggers an arc discharge between the anode electrode and the vapor deposition material. A vapor deposition source configured to evaporate a constituent material of the material, wherein the vapor deposition material in a space between the cylindrical anode electrode and the cylindrical trigger electrode is opposite to the deposition target The Spout inlet channel for introducing the hydrogen gas from the outside between are located.

  In the vapor deposition source of the present invention, since the jet port of the introduction path for introducing hydrogen gas from the outside of the space is located in the space between the cylindrical anode electrode and the cylindrical trigger electrode, The space can be efficiently filled with hydrogen gas, and the oxidation of the film and nanoparticles can be effectively suppressed.

Preferably, in the vapor deposition source of the present invention, a mixed gas of at least one reaction gas of nitrogen, argon and hydrocarbon and the hydrogen gas is ejected from the ejection port.
Preferably, in the vapor deposition source of the present invention, the partial pressure of the hydrogen gas in the mixed gas is 0.1 Pa to 50 Pa.

Particle formation apparatus of the present invention includes a deposition source, the deposition object holding means for holding the deposition target fine particles ionized generated from the vapor deposition material of the deposition source is deposited, the deposition source is cylindrical and Jo anode electrode, and a circle cylindrical cathode, a cylindrical trigger electrode, a deposition material connected to the cathode electrode, and arranged the insulator between the trigger electrode and the deposition material And the vapor deposition material is disposed at a position close to the trigger electrode, and when a voltage is applied to the trigger electrode, electrons due to trigger discharge are generated between the trigger electrode and the vapor deposition material. An evaporation source configured such that an arc discharge is induced between the anode electrode and the deposition material as a trigger, and a constituent material of the deposition material evaporates, and the cylindrical anode electrode and the circle On the opposite side of the deposition object with respect to the deposition material in the space between the Jo trigger electrodes, spout inlet channel for introducing the hydrogen gas from the outside of the space are positioned.

  ADVANTAGE OF THE INVENTION According to this invention, the vapor deposition source and fine particle formation apparatus which can suppress the oxidation of the film | membrane and nanoparticle of a to-be-deposited body can be provided.

FIG. 1 is a schematic view of a fine particle forming apparatus using a coaxial vacuum arc deposition source according to an embodiment of the present invention. FIG. 2 is a diagram for explaining the configuration of the coaxial vacuum arc deposition source shown in FIG.

  Hereinafter, a fine particle forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view of a fine particle forming apparatus 1 using a coaxial vacuum arc vapor deposition source 5.
FIG. 2 is a view for explaining the configuration of the coaxial vacuum arc deposition source 5 shown in FIG.
A vacuum chamber 2 shown in FIG. 1 has a cylindrical shape.
In the vacuum chamber 2, a deposition target holder 4 and a coaxial vacuum arc deposition source 5 are accommodated.
The vapor deposition body holding unit 4 detachably holds the vapor deposition body 3 which is a substrate or base material on which ionized fine particles from the coaxial vacuum arc vapor deposition source 5 are vapor deposited.

In coaxial vacuum arc evaporation source 5, as shown in FIG. 2, the gas line 101 for introducing a reactive gas such as N ₂ in the anode cylinder to generation of an arc discharge is provided, from its gas line 101 N ₂ gas, etc. The reactive gas and H ₂ gas are introduced to cause arc discharge of the target 3 in a pulsed manner, whereby it becomes possible to form a compound nanoparticle or a compound film with little oxygen contamination.
The gas line 101 is supplied with a gas from a gas supply source (not shown).

The reason why oxygen is mixed into the nanoparticles or the metal film is mainly due to the moisture H ₂ O adsorbed on the powder such as carbon black as the chamber wall, the components in the chamber and the base material, or the oxygen gas O ₂ in the residual gas. it is conceivable that.
(1) 1 / 2O ₂ = O [M]
(2) H ₂ O = 1 / 2O ₂ + H ₂
Or H ₂ O = O [M] + H ₂
Here, [M] indicates that it is adsorbed on the inner wall of the vacuum chamber 2.

For this reason conventional method, the vacuum chamber 2 sufficiently baked, also be sufficiently dehydrated with or held in a vacuum or by heating the powder of the base material, the wall Ya when the plasma operation by introducing N ₂ gas The inventor has found that moisture adsorbs in the powder and is blown out by plasma to become a new oxygen source.
Furthermore, the inventor has also found that as a problem inherent to nanoparticles, the nanoparticles are very surface active and easily incorporate oxygen.
In order to prevent oxygen from being taken into nanoparticles or metal films, the partial pressure of oxygen gas or moisture in the reaction atmosphere (vacuum wall, powder, etc.) in the above formulas (1) and (2) is reduced or reduced. It is conceivable to increase the partial pressure of H _{2 as} an agent. To increase the partial pressure of H ₂ is introduced H ₂ gas into the vacuum chamber 2, more (corresponding to increasing the H ₂ partial pressure) be excited strongly H ₂ gas for activating the H ₂ gas is necessary.

The plasma fire point in the coaxial vacuum arc deposition source 5 is the upper end surface of the deposition material 11 and the vicinity thereof. When a high voltage of about −3 kV is applied between the vapor deposition material 11 connected to the trigger electrode 13 and the cathode electrode 12, creeping discharge runs on the upper end surface of the low resistance alumina sandwiched between the vapor deposition material 11 and the trigger electrode 13. Some electrons are generated from the vapor deposition material 11 side, and this triggers an arc discharge between the vapor deposition material 11 (cathode) and the surrounding anode electrode 23.
Accordingly, the upper end surface of the vapor deposition material 11 where arc discharge occurs and the vicinity of the vapor deposition material 11 are fire points. If gas is made to flow here, the gas will be excited violently.
Accordingly, in order to lower the oxygen in the nanoparticles or in the film, H ₂ gas is introduced into the space between the anode electrode 23 and the trigger electrode 13, which is the fire point, using the gas line 101 as in this embodiment. It is effective to create a mechanism that can be introduced.

As shown in FIG. 2, in the coaxial vacuum arc deposition source 5, the tip of the gas line 101 from the outside of the vacuum chamber 2 is located in a region 201 between the inner peripheral surface of the anode electrode 23 and the outer peripheral surface of the trigger electrode 13. The part 101a is located.
H ₂ flows from the outside of the vacuum chamber 2 through the gas line 101 into the region 201 from the tip 101a.
As the gas line 101, for example, one of a plurality of (for example, three) support columns that support the coaxial vacuum arc deposition source 5 is used and a hollow structure is used.
The reaction of nitride by N ₂ gas was set to be introduced into the vacuum chamber 2 by using the N ₂ gas is also a gas line 101 because it is milder than oxidation with O2 gas.
That is, in the present embodiment, a mixed gas of N ₂ and H ₂ flows through the gas line 101.
Here, the partial pressure of the H ₂ gas in the mixed gas is preferably 0.1 Pa to 50 Pa, for example. It has been confirmed that the reason why the pressure is set to 0.1 Pa or more is that the reduction action is insufficient when the pressure is less than 0.1 Pa. Further, it has been confirmed that the reason why the pressure is 50 Pa or less is that the discharge of hydrogen plasma becomes unstable when the pressure exceeds 50 Pa.

The number of gas lines 101 may be singular or plural as shown in FIG. A plurality of gas lines 101 may be provided, and N ₂ gas and H ₂ gas may be ejected from different gas lines 101.

By introducing H ₂ gas into the anode electrode 23, the oxidation of the film and the nanoparticles could be suppressed. At the same time, N ₂ gas is also introduced through this gas line, so that N ₂ gas is sufficiently excited by plasma and is sufficiently nitrided without oxidation, such as nitrides or carbonitrides such as Nb, Ta, Ti, and Zr. Films and nanoparticles can be formed.

  The coaxial vacuum arc deposition source 5 has an anode electrode 23 in which stainless steel is formed in a cylindrical shape.

  The coaxial vacuum arc deposition source 5 includes a cathode electrode 12, a deposition material 11, a trigger electrode 13, and an insulator 14.

  An end portion of a disk-shaped base flange (not shown) is fixed to the inner side surface of the anode electrode 23 described above, and the cathode electrode 12 has a cylindrical shape, and this base flange (not shown). ) And in a state of being insulated from the base flange (not shown).

  The vapor deposition material 11 is connected to the evaporation portion formed in a columnar shape, with one end (not shown) being clamped to the cathode electrode 12.

Around the vapor deposition material 11, an insulator 14 and a ring-shaped trigger electrode 13 arranged around the insulator 14 are arranged. The insulator 14 is composed of a cylindrical portion and a collar portion, and is called a hat-type insulator because of its shape.
The trigger electrode 13 is insulated from both the cathode electrode 12 and the vapor deposition material 11 by the hat-type insulator 14.

  One end of a trigger wiring 21 is connected to the trigger electrode 13.

  As described above, the trigger wiring 21, the cathode electrode 12, and the anode electrode 23 are accommodated in the vacuum chamber 2, and the cathode electrode 12, the trigger wiring 21, and the anode electrode 23 are arranged in an airtight manner through the mounting flange. Connected to one end of each of the current introduction terminals. The other end of each current introduction terminal is exposed to the outside of the vacuum chamber 2, and both are connected to the power supply device 6 disposed outside the vacuum chamber 2.

  The power supply device 6 includes a trigger power supply 31, an arc power supply 32, and a capacitor unit 33. The trigger power supply 31 is configured to apply a positive pulse voltage of about 3 kV to the vapor deposition material 11 to the trigger electrode 13. On the other hand, the arc power source 32 is configured to apply a negative DC voltage of 400 V to the vapor deposition material 11 with respect to the anode electrode 23. The capacitor unit 33 has a capacity of 720 μF and is charged by the arc power supply 32.

  In the case of forming a thin film on the substrate surface using the fine particle forming apparatus 1 having the above-described configuration, first, the inside of the vacuum chamber 2 is set in a high vacuum atmosphere.

  Next, a negative DC voltage of 400 V is applied to the vapor deposition material 11 with respect to the anode electrode 23 by the arc power source 32. In this state, the trigger power supply 31 is activated and a positive pulse voltage of about 3 kV is applied to the trigger electrode 13.

Then, a trigger discharge is generated on the surface of the insulator 14 by applying a distance (about 1 mm) corresponding to the thickness of the cylindrical portion of the insulator 14 between the surface of the vapor deposition material 11 and the surface of the trigger electrode 13. Creeping discharge occurs. By this trigger discharge, the constituent material of the vapor deposition material 11 is evaporated from the surface of the vapor deposition material 11, and vapor, ions, electrons, and the like are generated. Electrons are generated from the joint between the vapor deposition material 11 and the insulator 14.

  When the pressure in the anode electrode 23 rises due to the vapor, ions, electrons, etc., and the dielectric strength voltage between the anode electrode 23 and the vapor deposition material 11 decreases, the charge charged in the capacitor unit 33 causes the vapor deposition material 11 and Arc discharge occurs between the anode electrode 23 and the anode electrode 23. When a large amount of current flows into the vapor deposition material 11 due to the arc discharge and the vapor deposition material 11 evaporates due to Joule heat, a large amount of charged fine particles having a positive charge are emitted from the side surface of the vapor deposition material 11 toward the anode electrode 23. .

  A magnetic field is formed in the anode electrode 23 by the arc current generated by the arc discharge. Since the magnetic field exerts a force to push the positively charged particles in the direction of the opening of the anode electrode 23, the charged fine particles emitted toward the anode electrode 23 are emitted into the vacuum chamber 2, and the vapor deposition target 3 is injected toward the surface.

[Operation example of coaxial vacuum arc deposition source 5]
Electric charges are charged at a discharge voltage of 100 V by the arc power source 32. Here, the capacitor unit 33 is 720 μF.
By applying a trigger pulse of 3.4 kV from the trigger power supply 31 to the trigger electrode 13 and applying it between the vapor deposition material 11 attached to the cathode electrode and the trigger electrode 13 via the hat-type insulator 14, a hat-type Creeping discharge occurs on the surface of the insulator 14, the charge stored in the capacitor unit 33 is discharged between the deposition material 11 and the anode electrode 23, a large amount of current flows into the cathode electrode, and the deposition attached to the cathode electrode. The material 11 is formed from the liquid phase to the gas phase and further plasma.

  At this time, since a large amount of current (2000 A to 5000 A) flows in the cathode electrode between 200 μS and 500 μS, a magnetic field is formed in the vapor deposition material 11 attached to the cathode electrode. Electrons in the plasma fly under the coaxial vacuum arc deposition source 5 under the Lorentz force generated by the magnetic field formed by the deposition material 11 attached to the cathode electrode.

  For example, platinum ions, which are vapor deposition materials in the plasma, are polarized so that they are attracted to the electrons flying to the front of the coaxial vacuum arc deposition source 5 by Coulomb force and fly to the front of the coaxial vacuum arc deposition source 5. To come.

  As a result, the ions of the charged fine particles are aggregated on the deposition target 3 to form nanometer-scale particles.

Examples will be described below.
Using NbC the target 3, the N2 gas or _N 2 + _{H 2} gas was introduced directly into the anode from the gas line, discharge voltage: 100 V, the capacitor capacitance: 720MyuF, in the discharged Si wafer substrates and transparent 12000 shots 5HZ An NbCN film was formed on the glass substrate 3.
The substrate 3 was placed at a position 80 mm in front of the anode electrode 23. Table 1 shows the appearance and sheet resistance of the film at that time.

  Table 1 Film formation conditions, film appearance and sheet resistance

NbCN and NbN are both considered to be black metal films having a specific resistance of about 40 to 60 μΩ · cm.
However, the films discharged only with N ₂ were all dark brown translucent films, and the sheet resistance was as high as 1 to 30 kΩ / □.
This is because when only N ₂ is added, the moisture adsorbed on the wall in the vacuum chamber 2 is struck by the N ₂ plasma, and oxygen [O] is mixed into the film to form a film close to a dielectric. It is shown that.

On the other hand, when H ₂ was added at the same time, the deposited film was a black film and the sheet resistance was 50-60 Ω / □. This indicates that the film deposited under these conditions is an NbCN metal film. Therefore, it is well shown that the amount of [O] in the film can be drastically reduced by providing the gas line 101 on one of the arc plasma struts and directly introducing the H2 gas into the anode electrode 23. Yes.
This is an example of nitriding an NbC target, but the same result is obtained when T is produced by discharging a Ti target in an N 2 gas atmosphere. Incidentally, in this case, the composition of the TiN (O) film, which was made of only N2 gas, was Ti = 29%, N = 27%, O = 31%, and [O] was mixed in the film in a large amount (film thickness). XPS analysis results).

According to the fine particle forming apparatus 1, oxidation of the film and nanoparticles can be suppressed by introducing H ₂ gas into the anode electrode 23 of the coaxial vacuum arc deposition source 5 through the gas line 101.
In addition, according to the fine particle forming apparatus 1, N ₂ gas is also introduced into the anode electrode 23 through the gas line 101 at the same time, and thus nitride and carbon such as Nb, Ta, Ti, and Zr that are sufficiently nitrided without being oxidized. Nitride films and nanoparticles can be formed.

The present invention is not limited to the embodiment described above.
That is, those skilled in the art may make various modifications, combinations, subcombinations, and alternatives regarding the components of the above-described embodiments within the technical scope of the present invention or an equivalent scope thereof.
Further, in the above embodiment, a case has been exemplified flowing a mixed gas of H ₂ gas and N ₂ gas through the gas line 101, or may be flowing a mixed gas of between H ₂ hydrocarbons .

In another embodiment, when forming a metal carbide film using two targets of metal and carbon, if a mixed gas of Ar and H ₂ is introduced near the anode via the gas line 101, the participation of the metal carbon film is prevented. Also effective.
In these examples, the film is used to form a film, but it goes without saying that it can also be used to form nanoparticles and islands.

  The present invention is applied to a wide range of technical fields such as the automobile industry, energy industry, home appliance industrial chemical industry, etc. that handle fuel cell catalysts, photocatalysts, exhaust gas catalysts, and the like.

DESCRIPTION OF SYMBOLS 1 ... Fine particle formation apparatus 3 ... To-be-deposited body 5 ... Coaxial type vacuum arc deposition source 6 ... Power supply device 7 ... To-be-deposited body 11 ... Deposition material 12 ... Cathode electrode 14 ... Insulator 23 ... Anode electrode 31 ... Trigger power supply 32 ... Arc Power supply 33 ... Capacitor unit 101 ... Gas line

Claims (4)

A cylindrical anode electrode, and a circle cylindrical cathode, a cylindrical trigger electrode, a deposition material connected to the cathode electrode, and arranged the insulator between the trigger electrode and the deposition material Have
The vapor deposition material is disposed at a position close to the trigger electrode,
When a voltage is applied to the trigger electrode, electrons due to trigger discharge are generated between the trigger electrode and the deposition material, and arc discharge is induced between the anode electrode and the deposition material using the electrons as a trigger. A vapor deposition source configured to evaporate a constituent material of the vapor deposition material,
On the side opposite to the deposition target with respect to the vapor deposition material in the space between the cylindrical anode electrode and the cylindrical trigger electrode, there is a jet port of an introduction path for introducing hydrogen gas from the outside of the space. The deposition source that is located. The vapor deposition source according to claim 1, wherein a mixed gas of at least one reaction gas of nitrogen, argon, and hydrocarbon and the hydrogen gas is ejected from the ejection port. The vapor deposition source according to claim 2, wherein a partial pressure of the hydrogen gas in the mixed gas is 0.1 Pa to 50 Pa. A deposition source;
Has a deposition object holding means for holding the deposition target body ionized particles generated from the vapor deposition material of the deposition source is deposited,
The deposition source is
A cylindrical anode electrode, and a circle cylindrical cathode, a cylindrical trigger electrode, a deposition material connected to the cathode electrode, and arranged the insulator between the trigger electrode and the deposition material Have
The vapor deposition material is disposed at a position close to the trigger electrode,
When a voltage is applied to the trigger electrode, electrons due to trigger discharge are generated between the trigger electrode and the deposition material, and arc discharge is induced between the anode electrode and the deposition material using the electrons as a trigger. A vapor deposition source configured to evaporate a constituent material of the vapor deposition material,
Wherein on the side opposite to the deposition object with respect to the deposition material in the space between the cylindrical anode electrode and the cylindrical trigger electrode, spout inlet channel for introducing the hydrogen gas from the outside of the space The fine particle forming device is located.