JP2021190323A - Manufacturing method and manufacturing apparatus for energization heating wire - Google Patents

Abstract

To provide a manufacturing method and a manufacturing apparatus for an energization heating wire, capable of uniformly forming tantalum carbide on a surface.SOLUTION: A manufacturing method for an energization heating wire has both ends, in which methane gas is introduced into a chamber with a tantalum line hung to be folded in a vertical direction, and AC power is supplied to the tantalum line for heat generation to carbonize a surface of the tantalum line.SELECTED DRAWING: Figure 1

Description

The present invention relates to, for example, a method and an apparatus for manufacturing an energized heating wire used as a catalyst wire in a catalyst wire chemical vapor deposition apparatus.

Catalytic-Chemical Vapor Deposition (Cat-CVD) is one of the film formation methods. In this method, for example, a reaction gas is supplied to a catalyst wire heated to 1500 to 2000 ° C., and decomposition seeds (deposited seeds) generated by utilizing a contact reaction or a thermal decomposition reaction of the reaction gas are deposited on a substrate to be deposited. It is a film forming method.

The catalytic chemical vapor deposition method is similar to the plasma CVD method in that the decomposed species of the reaction gas are deposited on the substrate to form a film. However, since the catalytic chemical vapor deposition method produces decomposition species of the reaction gas on the high temperature catalytic wire, the surface loss due to plasma is higher than that of the plasma CVD method, which forms plasma to generate decomposition species of the reaction gas. There is an advantage that the utilization efficiency of the raw material gas is high.

Tantalum is widely used as a material for catalyst wires used in this catalytic chemical vapor deposition method. However, since the metal tantalum itself has a low creep strength at high temperatures, if the metal tantalum is used as it is as a catalyst wire, thermal elongation and fusing occur during heating. Therefore, when tantalum is used as a catalyst wire, a method is used in which tantalum is subjected to boronization treatment or carbonization treatment to raise the melting point of tantalum and cure it.

For example, in Patent Document 1, a core portion made of tantalum formed by introducing a carbon source gas into a vacuum chamber in which a tantalum wire is installed and applying a voltage to the tantalum wire, and the core portion thereof are described. Disclosed is an energized heating wire comprising a peripheral portion made of tantalum carbide to be coated.

Japanese Unexamined Patent Publication No. 2012-415676

In order to form a film with uniform characteristics over the surface of the substrate, such as when forming a film on a substrate using the catalytic chemical vapor deposition method, an energized heating wire in which tantalum carbide is uniformly formed on the surface is desired. It is rare.

In view of the above circumstances, an object of the present invention is to provide a method and an apparatus for manufacturing an energized heating wire capable of uniformly forming tantalum carbide on the surface.

In order to achieve the above object, the method for manufacturing an energized heating wire according to one embodiment of the present invention is:
Introduce methane gas into the chamber, which has both ends and is equipped with a tantalum wire suspended vertically.
AC power is supplied to the tantalum wire to generate heat, and the surface of the tantalum wire is carbonized.

In this configuration, since AC power is supplied to the tantalum wire to carbonize the surface of the tantalum wire, tantalum carbide can be uniformly formed on the surface of the tantalum wire over the entire length of the tantalum wire.

For example, the length of the energization heating wire may be 2 m or more.
As described above, the present invention is suitable for manufacturing a long energization heating wire having a length of 2 m or more.

The manufacturing apparatus according to the embodiment of the present invention includes a chamber, a methane gas supply unit, and a power source.
The chamber is installed inside by suspending the tantalum wire having both ends so as to be folded back in the vertical direction.
The methane gas supply unit supplies methane gas into the chamber.
The power source supplies AC power for generating heat to the tantalum wire in order to carbonize the surface of the tantalum wire under a methane gas atmosphere.

In this configuration, since AC power is supplied to the tantalum wire to carbonize the surface of the tantalum wire, tantalum carbide can be uniformly formed on the surface of the tantalum wire over the entire length of the tantalum wire.

The length of the tantalum wire may be 2 m or more.
As described above, the present invention is suitable for manufacturing a long energization heating wire having a length of 2 m or more.

As described above, according to the present invention, it is possible to provide a method and an apparatus for manufacturing an energized heating wire capable of uniformly forming tantalum carbide on the surface of the tantalum wire over the entire length of the tantalum wire. ..

It is a schematic block diagram of the manufacturing apparatus of the energizing heating wire which concerns on embodiment of this invention. It is the schematic sectional drawing of the energization heating wire manufactured by the said manufacturing apparatus. It is a schematic diagram of the energization heating wire manufactured by using the above-mentioned manufacturing apparatus under different manufacturing conditions, and is manufactured by carbonizing the energizing heating wire manufactured by carbonizing using AC power and carbonizing using DC power. The energizing heating wire is shown. It is a flow chart which shows the manufacturing method of the energization heating wire. It is a schematic diagram for demonstrating the mechanism which the carbonization treatment unevenness occurs.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Manufacturing equipment configuration]
FIG. 1 is a schematic configuration diagram of a catalyst wire manufacturing apparatus 1 as an energizing heating wire according to an embodiment of the present invention. By carbonizing the surface of the tantalum wire 60 using the manufacturing apparatus 1, the catalyst wire 6 as an energized heating wire having tantalum carbide formed on the surface can be manufactured.
The manufacturing apparatus 1 includes a vacuum chamber 3, a vacuum pump 4, a methane gas (CH ₄ ) supply unit 9 which is a carbon source supply unit, a commercial power supply 11, and an AC power supply unit 18.

The vacuum chamber 3 is configured so that a plurality of tantalum wires 60 can be installed inside.
The vacuum pump 4 is connected to the vacuum chamber 3. The vacuum pump 4 enables the vacuum chamber 3 to be evacuated to a predetermined degree of vacuum.
The methane gas supply unit 9 supplies methane gas into the vacuum chamber 3.

The tantalum wire 60 is made of metal tantalum and has a rod shape. Each tantalum wire 60 having both ends hangs vertically in the vacuum chamber 3 (in the present embodiment, the direction of gravity) and is folded vertically in the lower region of the vacuum chamber 3 to form a vacuum. Suspended in chamber 3. The plurality of tantalum wires 60 are arranged in a straight line at predetermined intervals from each other. In the following description, the rowing direction of the plurality of tantalum wires 60 is referred to as "X-axis direction", the vertical direction is referred to as "Z-axis direction", and the direction orthogonal to these is referred to as "Y-axis direction".
The tantalum wire 60 is provided, for example, about 8 units, but FIG. 1 shows a state in which 3 units of the tantalum wire 60 are arranged in a row for easy explanation.

The length of the tantalum wire 60 varies depending on the size of the substrate to be formed by the catalytic chemical vapor deposition method using the catalyst wire 6 formed by carbonizing the surface of the tantalum wire 60. For example, a catalyst wire 6 having a length of 2 m to 6 m is used. The preferred length of the catalyst wire 6 is 2 m to 5 m, and in the present embodiment, the tantalum wire 60 having a length of the catalyst wire 6 before carbonization treatment of 4.5 m is used. The lengths of the tantalum wire 60 and the catalyst wire 6 formed by carbonizing the surface of the tantalum wire 60 are the same.
As shown in FIG. 1, in one tantalum wire 60, the tantalum wires 60 are arranged so that the lengths of the tantalum wires 60 from the two connection terminals 64 to the folded portion are equal to each other. More specifically, in the present embodiment, as shown in FIG. 3, the tantalum wire 60 (catalyst wire 6) has a folded portion length b of 120 mm and a length a in the Z-axis direction of 2200 mm. It is folded back and installed in the vacuum chamber 3.

The AC power supply device 18 is provided outside the vacuum chamber 3 and is connected to the commercial power supply 11. Each tantalum wire 60 is connected to an AC power supply device 18. The connection method may be parallel. Specifically, both ends of each tantalum wire 60 are connected to a connection wiring 63 arranged outside the vacuum chamber 3 via a connection terminal 64, and each connection wiring 63 is connected to an AC power supply device 18. ..

The commercial power supply 11 includes 100V, 110V, 200V, 220V, and the like, and the AC power supply device 18 can control the output voltage between 100 and 220V, for example. Further, although it depends on the size of the tantalum wire 60, the AC power supply device 18 applies a current of, for example, 10 to 50 A to the tantalum wire 60. Typically, the AC power supply unit 18 applies 30 A, 4.0 kW of AC power to the tantalum wire 60. The frequency of the AC voltage applied to the tantalum wire 60 by the AC power supply device 18 is, for example, 10 to 100 Hz, typically 50 to 60 Hz.

The AC power supply device 18 performs switching by a direct switching method that directly switches the AC output signal from the commercial power supply 11. However, the AC power supply device that controls the voltage by the switching element is not limited to the direct switching system, and may be an inverter system equipped with a converter (AC / DC converter).

In the carbonization treatment of the surface of the tantalum wire 60, methane gas is supplied into the vacuum chamber 3 and an AC voltage is supplied to the tantalum wire 60 to obtain a catalyst wire 6 in which tantalum carbide is uniformly formed on the surface. can. Details will be described later.
The manufacturing apparatus 1 is configured as described above.

[Structure of catalyst wire (energized heating wire)]
Next, the configuration of the catalyst wire 6 will be described. FIG. 2 is a cross-sectional view schematically showing the cross-sectional structure of the catalyst wire 6. As described above, the catalyst wire 6 is formed by carbonizing the surface of the tantalum wire 60. The catalyst wire 6 has a core portion 6a and a peripheral portion 6b. The core portion 6a is the central portion of the catalyst wire 6, and the peripheral edge portion 6b is the outer peripheral portion of the catalyst wire covering the core portion 6a. The core portion 6a is made of metal tantalum (Ta), and the peripheral portion 6b is made of tantalum carbide (TaC _x ).

Since metal tantalum has a low creep strength at high temperatures, catalytic heat rays composed only of metal tantalum may cause thermal elongation or fusing during film formation. On the other hand, in the catalyst wire 6 according to the present embodiment, the core portion 6a made of metal tantalum is covered with the peripheral portion 6b made of tantalum carbide having high creep strength at high temperature and high mechanical strength. The thermal and mechanical durability of 6 can be made high. Specifically, the catalyst wire made of only metal tantalum often needs to be replaced every time the film is formed, but the catalyst wire 6 according to the present embodiment is used for multiple film formations without requiring replacement. It is possible to do.

On the other hand, tantalum carbide has lower conductivity (larger electrical resistance) than metal tantalum, and a catalyst wire consisting only of tantalum carbide requires a large amount of electric power for heating. On the other hand, the catalyst wire 6 according to the present embodiment has a high conductivity (small electric resistance) because the inside of the cross-sectional structure is a core portion 6a made of metal tantalum, and is about the same as a catalyst wire made of only metal tantalum. It is possible to heat by the applied voltage of.
Further, since tantalum carbide is highly stable against chemical reactions, it is possible to prevent the diffusion of boron into the core material used in the film forming process in the catalytic chemical vapor phase growth method using a catalytic wire. As a result, it is possible to prevent the core material from being blown due to the local increase in resistance of the core material due to the boring of tantalum and the accompanying temperature rise of the core material, and it is possible to improve the durability of the core material. Therefore, the life of the catalyst wire can be extended.

[Manufacturing method of catalyst wire (energized heating wire)]
In the present embodiment, by carbonizing the surface of the tantalum wire by the following method using the manufacturing apparatus 1, it is possible to obtain a catalyst wire in which tantalum carbide is uniformly formed on the surface. Hereinafter, the description will be given according to the manufacturing flow of FIG.

One or more tantalum wires 60, which are the elements of the catalyst wire 6, are installed inside the vacuum chamber 3 of the manufacturing apparatus 1 (S11). The tantalum wire 60 is a wire made of metal tantalum, and its diameter can be several mm, and here it is 1.0 mm. The vacuum pump 4 is operated to evacuate the inside of the vacuum chamber 3 to reduce the pressure. Here, the pressure was reduced to less than 0.05 Pa.

Next, methane gas is introduced from the methane gas supply unit 9 into the reaction chamber 2 until it reaches a predetermined pressure, here 10 Pa. In a methane gas atmosphere, the surface of the surface of the tantalum wire 60 is heated by supplying AC power of 30 A and 4.0 kW to each tantalum wire 60 between both ends by the AC power supply device 18. Carbonization treatment is performed (S12). Here, the carbonization treatment time was set to 30 minutes.
The tantalum wire 60 is heated by resistance heating generated by the supply of AC power. The exothermic temperature of the tantalum wire 60 is set to a temperature at which acetylene (C ₂ H ₂ ) can be produced due to thermal desorption of hydrogen in methane gas. Contact of acetylene on the surface of the tantalum wire 60 forms a peripheral portion 6b made of tantalum carbide, which is a reaction product, on the surface of the tantalum wire 60. That is, a catalyst wire 6 having a linear core portion 6a made of tantalum and a peripheral edge portion 6b made of tantalum carbide and covering the core portion 6a is manufactured. The carbonization treatment time is, in other words, the heating time of the tantalum wire 60.

The heating temperature of the tantalum wire 60 can be set in the range of 1000 ° C. or higher and 2400 ° C. or lower. Here, the alternating current value is set to 30 A, but the present invention is not limited to this, and can be set in the range of, for example, 10 A to 60 A. Further, the AC power is set to 4.0 kW, but the present invention is not limited to this, and for example, it can be set in the range of 3 kW to 10 kW. The current value and the power value can be appropriately set according to the thickness and length of the catalyst wire.
The carbonization treatment time (heating time) is appropriately set according to the heating temperature of the tantalum wire 60. If other conditions are similar, the higher the heating temperature, the more the formation of tantalum carbide will proceed. Further, under the same conditions as other conditions, if the heating time is long, the formation of tantalum carbide proceeds.

Further, here, the pressure of the methane gas atmosphere is set to 10 Pa, but the pressure is not limited to this, and can be set to, for example, 1 Pa to 10 Pa. If other conditions are similar, the higher the pressure in the carbon atmosphere, the more tantalum carbide will be formed.

In the carbonization treatment of the surface of the tantalum wire 60, methane gas is used as the introduction gas and AC power is applied to the tantalum wire 60 to obtain a catalyst wire 6 in which tantalum carbide is uniformly formed on the surface. Hereinafter, it will be described with reference to FIG.
FIG. 3A shows a catalyst wire 6 manufactured by applying AC power during carbonization treatment, and FIG. 3B shows a catalyst wire 61 manufactured by applying DC power during carbonization treatment.
The catalyst wire 6 shown in FIG. 3A is manufactured by the above-mentioned manufacturing method, and is a catalyst wire having a yellow surface on which tantalum carbide is uniformly formed from one end to the other end.
On the other hand, the catalyst wire 61 shown in FIG. 3B is a catalyst wire manufactured under the same conditions as the above-mentioned manufacturing method except that the DC power of 30A and 4.0 kW is supplied to the tantalum wire 60. In FIG. 3B, the shaded area indicates a region where carbon is deposited on the surface. As shown in FIG. 3 (B), the catalyst wire 61 carbonized using DC power is folded back and tantalum carbide is formed in the portion located on the + pole side, and the surface is yellow, while the minus pole is formed. Carbon is deposited on the portion located on the side and the surface is black.

As described above, in the catalyst wire 61 manufactured by applying DC power, carbon is deposited on a part thereof, and tantalum carbide is not uniformly formed over the entire length of the tantalum wire 60, and uneven formation of tantalum carbide (hereinafter referred to as “tantalum carbide”) is not formed. , May be called uneven carbonization treatment.). Such uneven formation of tantalum carbide occurred in the same manner when DC power was used even if the treatment conditions such as the pressure of methane gas and the carbonization treatment time were changed.
Further, such uneven formation of tantalum carbide is caused by the length in the vertical direction when the tantalum wire, which is the source of the catalyst wire, is suspended in the manufacturing apparatus 1 so as to be folded back in the vertical direction (in FIG. 3A). It occurred remarkably when the length a) was 1 m or more.

The mechanism of occurrence of uneven formation of tantalum carbide in the catalyst wire 61 manufactured by applying the DC power shown in FIG. 3B is considered as follows. FIG. 5 is a diagram for explaining the mechanism of occurrence of uneven formation of tantalum carbide.

FIG. 5A is a diagram schematically showing the process of decomposition of methane gas and the state of carbon infiltration into the tantalum wire 60. FIG. 5B is a diagram schematically showing how carbon-12 infiltrates into the tantalum wire 60. In FIG. 5, carbon is designated by reference numeral 12, and hydrogen is designated by reference numeral 13.
The tantalum wire 60 is heated by the supply of DC electric power. As shown in FIG. 5A, methane (CH ₄ ) comes into contact with the tantalum wire 60 and thermal desorption of hydrogen occurs, so that a methyl group (CH ₃ ) and a hydrogen ion (H) are generated. This methyl group reacts with methane to _{generate ethane (C 2} H ₆ ) and hydrogen ions. _{Acetylene (C 2} H ₂ ) and hydrogen (H ₂ ) are produced by the contact of ethane with the tantalum wire 60 and the thermal desorption of hydrogen. When acetylene comes into contact with the tantalum wire 60 and thermal desorption occurs, carbon (C) and hydrogen are generated. In this way, the tantalum wire 60 is repeatedly in contact with the heat desorption, and as shown in FIG. 5B, carbon-12 infiltrating the tantalum wire 60 is obtained. Carbon-12 infiltrates and diffuses into the tantalum wire 60, and the surface of the tantalum wire 60 is carbonized to form tantalum carbide.
As shown in FIG. 5 (A), a methyl group having a negative polarity is generated in the process up to carbon infiltration. Here, when DC power is supplied to the tantalum wire 60 during the carbonization treatment, the methyl group having a negative polarity is attracted to the + pole side of the tantalum wire 60. As a result, in the tantalum wire 60, the electric field concentration differs between the positive pole side and the negative pole side, and an electric field concentration distribution is generated. Therefore, the amount of carbon infiltrated on the positive pole side is larger than that on the negative pole side, and carbonization proceeds.
Since the resistance value increases due to the formation of tantalum carbide, a resistance difference occurs between the positive pole side and the negative pole side as shown in FIG. 5 (C). When DC power is supplied with this resistance difference occurring, the heat generation temperature on the + pole side and the-pole side of the tantalum wire 60 is different, and the temperature on the + pole side is higher than that on the-pole side. Become. The higher the temperature, the more carbonization of tantalum progresses, so that carbonization of the surface of the positive pole side further progresses more than that of the negative pole side. On the other hand, since the temperature on the negative pole side is low, carbonization of tantalum does not proceed easily, and it infiltrates into the tantalum wire 60, and carbon that does not contribute to carbonization becomes an excess state, and the carbon precipitates on the surface of the tantalum wire 60. , Becomes black. In this way, when carbonization is performed using DC power, it is considered that carbonization unevenness occurs between the + pole side and the-pole side.

In the present embodiment, since AC power is supplied to the tantalum wire 60, the electric field concentration distribution does not occur on the + pole side and the-pole side as described above. Therefore, the generation of the resistance difference between the + pole side and the-pole side, and eventually the heating temperature difference is suppressed, and as a result, the occurrence of carbonization treatment unevenness is suppressed. As a result, the catalyst wire 6 having uniform tantalum carbide formed on the surface over the entire length can be obtained. Regardless of the length of the tantalum wire, a catalyst in which uniform tantalum carbide is formed on the surface over the entire length by supplying AC power to the tantalum wire 60 in a methane gas atmosphere to carbonize the tantalum wire. The wire 6 can be stably obtained.

As described above, the degree of formation of tantalum carbide in the catalyst wire varies depending on the heating temperature, heating time, pressure of the carbon atmosphere, and the like. By appropriately adjusting these conditions, it is possible to produce a catalyst wire 6 in which the core portion 6a is made of tantalum and the peripheral portion 6b is made of tantalum carbide.
Further, by supplying AC power to the tantalum wire 60 to carry out carbonization treatment of the tantalum wire 60, it is possible to obtain a catalyst wire 6 in which uniform tantalum carbide is formed on the surface over the entire length. As described above, when the tantalum wire is carbonized by supplying DC power, the uneven formation of tantalum carbide is the vertical length when the tantalum wire is suspended so as to be folded back in the vertical direction in the manufacturing apparatus 1. Is remarkably generated when is 1 m or more. Therefore, when carbonizing a tantalum wire having a total length of 2 m or more, it is particularly effective to supply AC power to the tantalum wire to perform the carbonization treatment.

A desired film can be formed on a substrate by a catalytic chemical vapor deposition method using a film forming apparatus (not shown) provided with the catalyst wire 6 described above. Specifically, the substrate is vertically arranged facing a plurality of catalyst wires 6 installed so as to hang vertically in the film forming apparatus. Then, AC power is supplied to the catalyst wire 6 to heat it, and the raw material gas is introduced into the film forming apparatus to form a film. The raw material gas comes into contact with the catalyst wire 6 heated to a high temperature, and the decomposed species of the reaction gas generated by the catalytic reaction or the thermal decomposition reaction are deposited on the substrate to form a film.
By forming a film using the catalyst wire 6 in which tantalum carbide is uniformly formed on the surface over the entire length obtained in the present embodiment, a film having stable in-plane film characteristics can be formed. .. Further, since tantalum carbide is uniformly formed on the surface of the catalyst wire 6 over the entire length, the thermal and mechanical durability is high. This prevents heat elongation and fusing of the catalyst wire 6 during film formation, and it is not necessary to frequently replace the catalyst wire after film formation, so that it is possible to improve the productivity of film formation.

The present invention is not limited to this embodiment, and may be modified without departing from the gist of the present invention.
In the above-described embodiment, the energized heating wire in which tantalum carbide is formed on the surface of the tantalum wire has been described as an example, but the present invention is not limited to this. For example, tantalum carbide formed on the surface of the tantalum wire may be further coated with a coating layer composed of at least one of tantalum boride or boron to form an energizing heating wire. In this configuration, since the coating layer contains tantalum boride or boron, for example, an alloying reaction (silicide) with silicon used in the film forming process in the catalytic chemical vapor deposition method using an energized heating wire is performed. It can be prevented and the decrease in mechanical strength can be suppressed.

1 ... Manufacturing equipment 3 ... Vacuum chamber (chamber)
6 ... Catalyst wire (energized heating wire)
9 ... Methane gas supply unit 11 ... Commercial power supply (power supply)
60 ... Tantalum line

Claims (4)

Introduce methane gas into the chamber, which has both ends and is equipped with a tantalum wire suspended vertically.
A method for manufacturing an energized heating wire, in which AC power is supplied to the tantalum wire to generate heat and the surface of the tantalum wire is carbonized. The method for manufacturing an energized heating wire according to claim 1.
A method for manufacturing an energized heating wire, wherein the length of the energized heating wire is 2 m or more. Inside, a chamber in which the tantalum wire with both ends is hung so that it folds vertically,
A methane gas supply unit that supplies methane gas into the chamber,
A manufacturing apparatus including a power source that supplies AC power to generate heat of the tantalum wire in order to carbonize the surface of the tantalum wire in a methane gas atmosphere. The manufacturing apparatus according to claim 3.
A manufacturing apparatus in which the length of the tantalum wire is 2 m or more.

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