Electrode device and method of manufacturing the same

Abstract

To provide an electrode device capable of suppressing contamination from a substrate and shortening a graphite electrode in use to lower manufacturing costs.SOLUTION: There is provided an electrode device that has a substrate joining and holding a graphite electrode, used for an arc discharge for manufacturing a quartz crucible, and has an anti-fouling thin film on an outermost surface of a surface of the substrate in a portion contiguous to the graphite electrode when the substrate is joined to the graphite electrode.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electrode device and a method for manufacturing the same, and more particularly to an electrode device used for manufacturing a quartz crucible and a method for manufacturing the same.

Background Art

[0002] Many of the silicon single crystals used as substrates for single crystal semiconductor materials are manufactured by the so-called Czochralski method in which silicon polycrystal is melted in a quartz crucible, brought into contact with a seed crystal, and then crystal growth is carried out. There are several types of quartz crucibles used in this method for manufacturing silicon single crystals depending on the manufacturing method. Practically, a quartz crucible manufactured by filling a rotatable hollow mold with silicon dioxide powder (raw material quartz powder) and heating and melting the silicon dioxide powder by arc discharge using a graphite electrode while rotating the mold is used. Many aspects have been disclosed regarding the graphite electrode used for arc discharge for manufacturing a quartz crucible (for example, Patent Documents 1 to 3). This graphite electrode is used in connection with an electrode device for energization (for example, one having a copper support) (for example, Patent Document 4).

[0003] Conventionally, in the arc rotation melting method, which is a method for manufacturing a quartz crucible, there has been a problem that contamination occurs when a metal support approaches a heat source. Therefore, for example, Patent Document 4 described above discloses an example in which in a method for manufacturing a quartz glass crucible by the arc rotation melting method, a carbon electrode (graphite electrode) inserted into a mold is composed of a rod-shaped portion made of carbon and its support, and at least a part of the rod-shaped portion made of carbon is extended above the high-temperature atmosphere inside the mold, and the support joined to the tip thereof is isolated from the high-temperature atmosphere. Thus, it is disclosed that the support to be joined is isolated from the high-temperature atmosphere by lengthening the graphite electrode. Further, Patent Document 4 discloses that the length of the carbon rod-shaped portion is preferably 20 cm to 2.5 m for isolation of the support.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, Patent Document 4 discloses isolating a support joined by lengthening a graphite electrode from a high-temperature atmosphere. However, there is a problem that the manufacturing cost due to graphite increases as the graphite electrode becomes longer.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide an electrode device that can suppress contamination from a support and reduce manufacturing costs by shortening the graphite electrode to be used. Another object is to provide a method for manufacturing an electrode device capable of manufacturing such an electrode device.

Means for Solving the Problems

[0007] The present invention is an electrode device having a support for joining and holding a graphite electrode used for arc discharge for manufacturing a quartz crucible, wherein, among the surfaces of the support, an antifouling thin film is provided on the outermost surface layer of the portion adjacent to the graphite electrode when the support is joined to the graphite electrode.

[0008] The electrode device of the present invention has an antifouling thin film on the outermost surface layer of the portion adjacent to the graphite electrode among the surfaces of the support, so that contamination from the support can be suppressed even in arc melting.

[0009] At this time, the antifouling thin film is preferably a sprayed film. Further, the sprayed film is preferably a ceramic sprayed film or an alloy sprayed film.

[0010] Such a ceramic sprayed film or alloy sprayed film can be easily made into a thin film having antifouling properties, heat resistance, impact resistance, and insulation properties. Therefore, an electrode device having such a thin film can more effectively suppress contamination from the support in arc melting.

[0011] Further, the antifouling thin film preferably covers at least a portion of the surface of the support that is inserted inside the mold used when manufacturing the quartz crucible.

[0012] By forming an antifouling thin film at least on such a portion, contamination from the support in arc melting can be more effectively suppressed.

[0013] Further, the material of the antifouling thin film is preferably at least one of alumina, zirconia, mullite, chromia, yttria, titania, ceria, alloys containing these, and alloys containing nickel.

[0014] These materials can be preferably used as the material of the antifouling thin film in the electrode device of the present invention.

[0015] Further, the material of the support preferably contains at least one of gold, silver, copper, and aluminum.

[0016] These metals are highly malleable metals that are easy to fix the graphite electrode, and also have high cooling performance and good conductivity, so they are preferable as the material of the support.

[0017] The antifouling thin film is preferably formed on the surface of the support via one or more underlying thin films.

[0018] Thus, by having the base thin film, the influence due to the difference in the coefficient of thermal expansion between the material of the support and the antifouling thin film can be reduced.

[0019] The present invention also provides an electrode characterized by being joined with any one of the above electrode devices and the graphite electrode.

[0020] Such an electrode has an antifouling thin film on the outermost surface layer of the portion adjacent to the graphite electrode on the surface of the support of the electrode device, and thus can suppress contamination from the support even in arc melting.

[0021] In this case, it is preferable that the length of the rod-shaped portion of the graphite electrode is 50 mm or more and 500 mm or less.

[0022] An electrode using a graphite electrode having a rod-shaped portion of such a length can perform sufficient arc discharge at low cost.

[0023] The present invention also provides a method for manufacturing an electrode device having a support for joining and holding a graphite electrode used for arc discharge for manufacturing a quartz crucible, the method including: a step of preparing the electrode device; and a step of forming an antifouling thin film on the outermost surface layer of the portion adjacent to the graphite electrode on the surface of the support of the prepared electrode device when the support is joined with the graphite electrode.

[0024] By such a method for manufacturing an electrode device, an electrode device having an antifouling thin film on the outermost surface layer of the portion adjacent to the graphite electrode on the surface of the support can be manufactured, and the electrode device can be made to be able to suppress contamination from the support even in arc melting.

[0025] In this case, it is preferable that the step of forming the antifouling thin film is performed by thermal spraying. Further, the thermal spraying is preferably ceramic thermal spraying or alloy thermal spraying.

[0026] The ceramic spraying or alloy spraying of the present invention can easily form a coating. As a result, a thin film having antifouling properties, heat resistance, impact resistance, and insulation can be obtained by a simple method. Therefore, an electrode device having such a thin film can more effectively suppress contamination from the support in arc melting.

[0027] Also, it is preferable that the material of the antifouling thin film is at least one of alumina, zirconia, mullite, chromia, yttria, titania, ceria, alloys containing these, and alloys containing nickel.

[0028] These materials can be preferably used as the material of the antifouling thin film in the manufacturing method of the electrode device of the present invention.

[0029] Also, before the step of forming the antifouling thin film, it has a step of forming one or more underlying thin films on the surface of the support, and the antifouling thin film is preferably formed on the underlying thin film.

[0030] In this way, by forming the underlying thin film, the influence due to the difference in the coefficient of thermal expansion between the material of the support and the antifouling thin film can be reduced.

Effects of the Invention

[0031] The electrode device of the present invention has an antifouling thin film on the outermost surface layer of the portion of the surface of the support adjacent to the graphite electrode. By doing so, in arc melting, the amount of graphite consumed by the graphite electrode that forms the electrode by connection can be reduced, and contamination of the quartz crucible manufactured from the support can be suppressed. Further, the graphite electrode can be shortened, and the cost of the graphite electrode for manufacturing the quartz crucible can be reduced. Also, the amount of graphite consumed during arc melting can be reduced, and contamination of the quartz crucible can be reduced. Further, since the graphite electrode can be shortened, waste carbon can be reduced, which can also contribute to the SDGs. Further, the manufacturing method of the electrode device of the present invention can manufacture such an electrode device.

Brief Description of the Drawings

[0032]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0033] Hereinafter, the present invention will be described more specifically.

[0034] The electrode device of the present invention is an electrode device having a support for joining and holding a graphite electrode used for arc discharge for manufacturing a quartz crucible, and among the surfaces of the support, when the support is joined to the graphite electrode, it is characterized in that it has an antifouling thin film on the outermost surface layer of the portion adjacent to the graphite electrode.

[0035] Hereinafter, specific embodiments of the electrode device of the present invention and an electrode in which the electrode device is connected to a graphite electrode will be described with reference to the drawings.

[0036] FIG. 1 shows an aspect of the graphite electrode, the electrode device, and the electrode connecting these of the present invention. The electrode device 10 shown in FIG. 1 has a support 12 for joining and holding a graphite electrode 22. Here, the graphite electrode 22 is used for arc discharge for manufacturing a quartz crucible. In FIG. 1, a mold 52, raw material powder 62 that is melted by arc discharge to become a quartz crucible, and a lid 54 used during arc discharge are shown disposed within the mold 52. The electrode device 10 of the present invention has an antifouling thin film 14 on the outermost surface layer of the portion adjacent to the graphite electrode 22 among the surfaces of the support 12 when the support 12 is joined to the graphite electrode 22.

[0037] Such an electrode device 10 of the present invention has an antifouling thin film 14 on the outermost surface layer of the portion adjacent to the graphite electrode 22 among the surfaces of the support 12, so that contamination from the support 12 can be suppressed even during arc melting.

[0038] The support 12 of the electrode device 10 holds the graphite electrode 22 and, for example, has a holding portion connected to the connection portion of the graphite electrode 22. A known method can be used for connecting the support 12 and the graphite electrode 22 of the electrode device 10.

[0039] The antifouling thin film 14 provided on the support 12 of the electrode device 10 of the present invention is preferably a sprayed film. A known method can be adopted for the spraying method. As a ceramic spraying method, for example, the method disclosed in Japanese Patent Laid-Open No. 7-316773 can be adopted.

[0040] The thermal spraying of the present invention is preferably ceramic thermal spraying or alloy thermal spraying. The ceramic thermal spraying film or alloy thermal spraying film can be easily made into a thin film having antifouling properties, heat resistance, impact resistance, and insulation properties. Therefore, an electrode device having such a thin film can more effectively suppress contamination from the support in arc melting.

[0041] The material of the antifouling thin film 14 in the present invention is preferably at least one of alumina, zirconia, mullite, chromia, yttria, titania, ceria, and alloys containing these, and alloys containing nickel. These materials can be suitably used as the material of the antifouling thin film in the electrode device of the present invention. In particular, among alumina and alloys containing nickel, a material called colmonoy can be suitably used.

[0042] On the other hand, as the material of the support 12 of the electrode device 10, it is preferable to contain at least one of gold, silver, copper, and aluminum. Such metals are highly malleable metals that are easy to fix the graphite electrode, and also have high cooling performance and good conductivity, so they are preferable as the material of the support.

[0043] The antifouling thin film 14 is preferably formed on the surface of the support 12 of the electrode device 10 via one or more underlying thin films. This is because having the underlying thin film can reduce the influence caused by the difference in the thermal expansion coefficients between the material of the support 12 and the antifouling thin film 14. The material of the underlying thin film depends on the combination of the support 12 and the antifouling thin film 14, and a known material can be appropriately adopted. For example, for a support 12 containing at least one of gold, silver, copper, and aluminum, after performing a thermal spraying coating of an alloy containing Al and Mo with Ni as the main component as the underlying thin film, a thermal spraying coating of alumina can be performed.

[0044] The antifouling thin film 14 in the present invention preferably covers at least the portion of the surface of the support 12 that is inserted into the inside of the mold 52 used when manufacturing the quartz crucible. The inside of the mold 52 is the lower side than the upper end of the mold 52, and when using the lid 54, it is the lower side than the lid 54. In the case of the electrode device 10 and the electrode 30 shown in FIG. 1, the antifouling thin film 14 covers at least the portion inserted into the inside of the mold 52. Also, FIGS. 2 and 3 show the electrode device 10 and the electrode 30 of the present invention. Also in the case of FIG. 2, the antifouling thin film 14 covers at least the portion inserted into the inside of the mold 52. In the case of FIG. 3, all the portions inserted into the inside of the mold 52 are the portions of the graphite electrode 22.

[0045] On the other hand, FIG. 4 shows an example of using an electrode 130 connecting the support 112 of the electrode device 110 without an antifouling thin film and the graphite electrode body 122 for arc discharge for manufacturing a quartz crucible similar to FIGS. 1 to 3. In the case of FIG. 4, since the support 112 does not have an antifouling thin film, in order to prevent contamination of the quartz crucible by the support 112, it is necessary to form the graphite electrode 122 long, resulting in high cost. In the case of the present invention as shown in FIGS. 1 to 3, the cost can be reduced in any case compared to the embodiment of FIG. 4.

[0046] In particular, in the electrode 30 of the present invention, it is preferable that the length of the rod-shaped portion of the graphite electrode 22 is 50 mm or more and 500 mm or less. For the electrode 30 using the graphite electrode 22 having a rod-shaped portion of such a length, sufficient arc discharge can be performed while the cost is low. Note that the rod-shaped portion of the graphite electrode 22 is the portion excluding the portion housed inside the support 12 when connecting to the support 12 of the electrode device 10.

[0047] The present invention also provides a method for manufacturing an electrode device having a support for joining and holding a graphite electrode used for arc discharge for manufacturing a quartz crucible. The method for manufacturing this electrode device includes a step of preparing the electrode device, and a step of forming an antifouling thin film on the outermost surface layer of a portion adjacent to the graphite electrode when the support is joined to the graphite electrode, among the surfaces of the support of the prepared electrode device. By such a method for manufacturing an electrode device, an electrode device having an antifouling thin film on the outermost surface layer of a portion adjacent to the graphite electrode can be manufactured, and it can be assumed that the electrode device can suppress contamination from the support even in arc melting.

[0048] Also, in the method for manufacturing the electrode device of the present invention, before the step of forming the antifouling thin film, there is a step of forming one or more base thin films on the surface of the support, and the antifouling thin film can be formed on the base thin film. By forming the base thin film, the influence due to the difference in the thermal expansion coefficients between the material of the support and the antifouling thin film can be reduced.

[0049] Also, in the method for manufacturing the electrode device of the present invention, the step of forming the antifouling thin film is preferably performed by spraying. The spraying of the present invention is particularly preferably ceramic spraying or alloy spraying. Ceramic spraying or alloy spraying can easily form a coating film. Thereby, a thin film having antifouling properties, heat resistance, impact resistance, and insulation properties can be obtained by a simple method. Therefore, an electrode device having such a thin film can more effectively suppress contamination from the support in arc melting.

[0050] Also, the material of the antifouling thin film can be at least any one of alumina, zirconia, mullite, chromia, yttria, titania, ceria, and alloys containing these, and alloys containing nickel. These materials can be preferably used as the material of the antifouling thin film in the method for manufacturing the electrode device of the invention.

Example

[0051] Examples of the present invention will be described in more detail below. However, the present invention is not limited to the examples, and various modifications are possible without departing from the technical idea of the present invention.

[0052] (Example 1) Using the electrode device 10 and the electrode 30 of the aspect of the present invention shown in FIG. 1, a quartz crucible was manufactured.

[0053] First, the electrode device 10 was prepared. The material of the support 12 of the electrode device 10 was copper. Of the surface of the support 12 of this electrode device 10, a range of 450 mm was sprayed and coated from the connection portion to which the graphite electrode 22 was connected. For the sprayed coating, first, as the first layer of the base thin film, a thin film with a thickness of less than 0.1 mm was formed at a ratio of Ni:Al:Mo of about 85:10:5. Next, as the second layer of the antifouling thin film 14, a sprayed coating of alumina (white alumina, α-Al 2 O 3 , purity 99.8%) was performed with a thickness of 0.2 to 0.3 mm.

[0054] A graphite electrode 22 with a rod-shaped portion having a length of 70 mm was connected to the support 12 of this electrode device 10 to form an electrode 30.

[0055] Next, the raw material powder 62 was placed inside the mold 52. As shown in FIG. 1, the electrode 30 was inserted into the mold 52, and the lid 54 was installed. The insertion length of the support 12 into the mold 52 was 150 mm.

[0056] Next, an electric current was applied to the electrode 30 to perform arc discharge, melting the raw material powder 62 to manufacture a quartz crucible.

[0057] (Example 2) Using the electrode device 10 and the electrode 30 shown in FIG. 2, a quartz crucible was manufactured. In this example, except that the range of the sprayed coating on the surface of the support 12 was 400 mm, the length of the rod-shaped portion of the graphite electrode 22 was 130 mm, and the insertion length of the support 12 into the mold 52 was 100 mm, it was the same as in Example 1.

[0058] (Example 3) Using the electrode device 10 and the electrode 30 shown in FIG. 3, a quartz crucible was manufactured. In this example, the range of the thermal spraying coating on the surface of the support 12 was 300 mm, the length of the rod-shaped portion of the graphite electrode 22 was 300 mm, and the support 12 was not inserted into the inside of the mold 52. Otherwise, it was the same as in Example 1.

[0059] (Comparative Example 1) Using the electrode device 110 and the electrode 130 shown in FIG. 4, a quartz crucible was manufactured. In Comparative Example 1, no thermal spraying coating was performed on the support 112. The length of the rod-shaped portion of the graphite electrode 122 was 600 mm, and the support 112 was not inserted into the inside of the mold 52. Otherwise, it was the same as in Example 1.

[0060] (Comparative Example 2) Using the electrode device 110 and the electrode 130 shown in FIG. 5, a quartz crucible was manufactured. In Comparative Example 2, no thermal spraying coating was performed on the support 112. The length of the rod-shaped portion of the graphite electrode 122 was 130 mm, and the insertion length of the support 112 into the inside of the mold 52 was 100 mm. Otherwise, it was the same as in Example 1.

[0061] [Comparison of Examples 1 to 3 and Comparative Examples 1 and 2] Bulk analysis of the inner surface layer 1 mm of the quartz crucibles manufactured in Examples 1 to 3 and Comparative Examples 1 and 2 was performed, and the impurity concentration was measured. The conditions and results of each example and comparative example are summarized in Table 1.

[0062] TIFF2025088609000002.tif60161

[0063] According to the measurement results of the impurity concentration, contamination by Cu was observed in Comparative Example 2. Regarding the Fe concentration, there is no problem as long as it is at the level shown in Table 1 above. On the other hand, in Comparative Example 1, the manufacturing cost of the graphite electrode 122 increased significantly compared to the manufacturing costs of the graphite electrodes 22 in Examples 1 to 3. Also, the manufacturing cost of the graphite electrode 22 was the lowest in Example 1, increasing in the order of Examples 2 and 3, but all were less expensive than Comparative Example 1.

[0064] Based on the contamination degree and the manufacturing cost of the graphite electrode according to the metal impurity concentration, a comprehensive evaluation was performed and evaluated as good: 〇, acceptable: △, unacceptable: ×, and described in Table 1.

[0065] This specification includes the following inventions. [1]: An electrode device having a support for joining and holding a graphite electrode used for arc discharge for manufacturing a quartz crucible, characterized in that, among the surfaces of the support, an antifouling thin film is provided on the outermost surface layer of the portion adjacent to the graphite electrode when the support is joined to the graphite electrode. [2]: The electrode device according to [1] above, wherein the antifouling thin film is a sprayed film. [3]: The electrode device according to [1] or [2] above, wherein the antifouling thin film covers at least the portion of the surface of the support that is inserted into the mold used when manufacturing the quartz crucible. [4]: The electrode device according to any one of [1] to [3] above, wherein the antifouling thin film is a ceramic sprayed film or an alloy sprayed film. [5]: The electrode device according to any one of [1] to [4] above, wherein the material of the antifouling thin film is at least one of alumina, zirconia, mullite, chromia, yttria, titania, ceria, and alloys containing these, and alloys containing nickel. [6]: The electrode device according to any one of [1] to [5] above, wherein the material of the support contains at least one of gold, silver, copper, and aluminum. [7]: The electrode device according to any one of [1] to [6] above, wherein the antifouling film is formed on the surface of the support via one or more underlying films. [8]: An electrode characterized in that it is obtained by joining the electrode device according to any one of [1] to [7] above and the graphite electrode. [9]: The electrode according to [8] above, wherein the length of the rod-shaped portion of the graphite electrode is 50 mm or more and 500 mm or less.

[10] : A method for manufacturing an electrode device having a support for joining and holding a graphite electrode used for arc discharge for manufacturing a quartz crucible, comprising: a step of preparing the electrode device; a step of forming an antifouling film on the outermost surface layer of a portion adjacent to the graphite electrode when the support is joined to the graphite electrode, among the surfaces of the support of the prepared electrode device; A method for manufacturing an electrode device, characterized by comprising the above steps.

[11] : The method for manufacturing an electrode device according to

[10] above, wherein the step of forming the antifouling film is performed by thermal spraying.

[12] : The method for manufacturing an electrode device according to

[10] or

[11] above, wherein the step of forming the antifouling film is performed by ceramic spraying or alloy spraying.

[13] : The method for manufacturing an electrode device according to any one of

[10] to

[12] above, wherein the material of the antifouling film is at least one of alumina, zirconia, mullite, chromia, yttria, titania, ceria, alloys containing these, and alloys containing nickel.

[14] : Before the step of forming the antifouling film, it has a step of forming one or more underlying films on the surface of the support, The method for manufacturing an electrode device according to any one of

[10] to

[13] above, wherein the antifouling film is formed on the underlying film.

[0066] Note that the present invention is not limited to the above-described embodiments. The above embodiments are merely illustrative, and any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and exhibits the same operational effects is included in the technical scope of the present invention.

Explanation of Reference Numerals

[0067] 10, 110... Electrode device, 12, 112... Support, 14... Antifouling film 22, 120... Graphite electrode, 30, 130... Electrode 52... Mold, 54... Lid, 62... Raw material powder that melts into a quartz crucible

Claims

1. An electrode device having a support for joining and holding a graphite electrode used for arc discharge for manufacturing a quartz crucible, wherein a surface layer of a portion of the surface of the support adjacent to the graphite electrode when the support is joined to the graphite electrode has an antifouling thin film. The electrode device is characterized by this.

2. The electrode device according to claim 1, wherein the antifouling thin film is a sprayed film.

3. The electrode device according to claim 1, wherein the antifouling thin film covers at least a portion of the surface of the support that is inserted into a mold used when manufacturing the quartz crucible.

4. The electrode device according to claim 1, wherein the antifouling thin film is a ceramic sprayed film or an alloy sprayed film.

5. The electrode device according to claim 1, wherein the material of the antifouling thin film is at least one of alumina, zirconia, mullite, chromia, yttria, titania, ceria, alloys containing these, and alloys containing nickel.

6. The electrode device according to claim 1, wherein the material of the support contains at least one of gold, silver, copper, and aluminum.

7. The electrode device according to claim 1, wherein the antifouling thin film is formed on the surface of the support via one or more underlying thin films.

8. An electrode characterized by being joined with the graphite electrode and the electrode device according to any one of claims 1 to 7.

9. The electrode according to claim 8, wherein the length of the rod-shaped portion of the graphite electrode is 50 mm or more and 500 mm or less.

10. A method for manufacturing an electrode device having a support for joining and holding a graphite electrode used for arc discharge for manufacturing a quartz crucible, comprising the steps of preparing the electrode device, and forming an antifouling thin film on a surface layer of a portion of the surface of the support of the prepared electrode device adjacent to the graphite electrode when the support is joined to the graphite electrode. The method for manufacturing an electrode device is characterized by having these steps.

11. The method for manufacturing an electrode device according to claim 10, wherein the step of forming the antifouling thin film is performed by spraying.

12. ​ The method for manufacturing an electrode device according to claim 10, wherein the step of forming the antifouling thin film is performed by ceramic spraying or alloy spraying.

13. The method for manufacturing an electrode device according to claim 10, wherein the material of the antifouling thin film is at least one of alumina, zirconia, mullite, chromia, yttria, titania, ceria, alloys containing these, and alloys containing nickel.

14. Before the step of forming the antifouling thin film, the method includes a step of forming one or more underlying thin films on the surface of the support, The antifouling thin film is formed on the underlying thin film, and the method for manufacturing an electrode device according to claim 10 is characterized by this.

Images