JP2006059633A - heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heater capable of heat-treating stably without losing airtightness of the heater even in the case a high temperature heat-treatment is carried out to a substrate such as a silicon wafer. <P>SOLUTION: This heater is provided with a light-emitting tube which is composed of a ceramic material and at which a carbon-wire heating element formed by carbon in the inner part is arranged and installed, and the base member jointed to both ends of the light-emitting tube. The heating element has an electric resistance reducing part for reducing the electric resistance at least at a part corresponding to joining parts to the light-emitting tube and the base member. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heater used in industrial heating fields, for example, heating devices such as semiconductor heating and glass substrate heating. More specifically, the present invention relates to a heater having a high heat resistance and a carbon heating element disposed inside an arc tube made of ceramics such as sapphire.

  Currently, in the semiconductor manufacturing process, for example, a film forming step for forming an oxide film on the surface of a substrate such as a silicon wafer, or impurity ions such as boron and arsenic are implanted into a silicon crystal in a surface layer portion of the silicon wafer. In the state, when performing a diffusion step of diffusing the impurity, a predetermined heat treatment is performed.

  The heating means used in the above process is required not to be a source of substances that degrade the performance of silicon wafers such as impurity metals. Therefore, the heat treatment is less likely to generate an impurity metal or the like, for example, the outside of a rod-shaped heating element made of tungsten is covered with an arc tube made of quartz glass, and for the purpose of preventing oxidation of the heating element in the arc tube, for example, This is performed using a tubular heater in which an inert gas such as nitrogen gas or argon gas is sealed.

From the viewpoint of preventing such impurity metal contamination, carbon produced by knitting a plurality of very thin carbon fibers, which can be suitably used as a heating means for a semiconductor manufacturing process, compared to a solid rod-like metallic heating element. Patent Document 1 discloses a heater in which a wire heating element is disposed in a quartz glass tube.
JP 2002-15849 A

  By the way, at the time of heating for a recent semiconductor manufacturing process, a heat treatment at a high temperature of 1200 ° C. or higher may be required for a substrate such as a silicon wafer. However, when such a high-temperature heat treatment is performed using a conventional heater, the quartz glass tube covering the outside of the heating element is melted and deformed, so that the heating element is deteriorated by impairing the hermeticity of the heater. It has been found that the problem of oxidation occurs.

  In order to solve such a problem, the present invention provides a heater that can stably perform a heat treatment without impairing the hermeticity of the heater even when a high-temperature heat treatment is performed on a substrate such as a silicon wafer. The purpose is to provide.

  In order to solve the above-described problems, the present invention includes an arc tube having a carbon wire heating element formed of carbon and made of a ceramic material, and a base member joined to both ends of the arc tube. Thus, the heating element has an electrical resistance reducing portion for reducing the electrical resistance at least at a location corresponding to a location where the arc tube and the base member are joined.

  Further, the arc tube is made of sapphire.

  Further, the base member is made of an insulating material, and is joined by an arc tube made of sapphire and frit glass.

  Further, the base member is made of a conductive material, and is joined to an arc tube made of sapphire by brazing.

  Furthermore, the electrical resistance reduction unit is made of a conductive member.

  Further, the conductive member is made of carbon.

  Furthermore, the heating element is compressed and fixed to a wire carbon member filled in the base member, and is electrically connected to the wire carbon member.

  Further, the base member is connected to a conductive member at an end opposite to the side connected to the arc tube, and the conductive member is electrically connected to the heating element at a reduced diameter portion formed in a part thereof. It is characterized by being connected to.

According to the heater of the present invention, since the arc tube is made of ceramics having high heat resistance such as sapphire, the heat resistance is improved as compared with the case where quartz glass is used for the arc tube. Even when the heater is driven to realize a high-temperature heat treatment exceeding, for example, 1200 ° C. required in the process, there is no problem that the arc tube is melted and deformed.
Furthermore, the carbon heating element is provided with an electrical resistance reducing section for reducing the electrical resistance at least at a location corresponding to the location where the arc tube and the base member are joined. Even in such a case, it is possible to suppress an excessive increase in the temperature of the joining portion made of frit glass or brazing material that joins the arc tube and the base member. There is nothing to do.
From the above, it is possible to surely solve the problem that the heating element oxidizes due to the loss of the airtightness of the heater under high temperature conditions, and thus stable heat treatment can be performed.

FIG. 1 shows a cross-sectional view of the heater of the present invention cut in the tube axis direction. FIG. 2 is an enlarged view of a main part of the heater of the present invention.
As shown in FIG. 1, the carbon heater 1 includes an arc tube 11 made of sapphire and an insulating material made of, for example, alumina. Each end of the arc tube 11 is fitted into one end and joined to the arc tube 11. The cylindrical base member 12 and the inside of the arc tube 11 are penetrated, and both ends thereof protrude outward from the arc tube 11 and are arranged in the base member 12 along the tube axis direction of the arc tube 11. The heating element 13 is arranged. The heating element 13 is embedded and fixed in a compressed state in the wire carbon member 14 compressed and accommodated in the internal space of the base member 12. In the base member 12, the inside of the heater 1 including the arc tube 11 and the base member 12 is formed by fitting a closing member 15 into an opening formed at the end opposite to the side joined to the arc tube 11. Keeped airtight.

  Since it is necessary for the arc tube 11 to be excellent in high-temperature durability, the arc tube 11 is preferably made of a ceramic material excellent in high-temperature durability, and particularly preferably made of sapphire. Since sapphire has a high melting point of 2053 ° C., the arc tube made of sapphire has excellent high-temperature durability as compared to a conventional arc tube made of quartz glass (softening point is 1200 ° C.). In order to meet the demand, it is possible to increase the input power to the heating element. Further, since sapphire is superior to quartz glass in infrared transmittance, the performance of the heater is improved by configuring the arc tube with sapphire.

  The base member 12 is a cylindrical body made of alumina and having an internal space in order to ensure electrical insulation. The end of the arc tube 11 is fitted into the base member 12 by a predetermined length, and the arc tube 11 and the base member 12 are integrated in the tube axis direction. The arc tube 11 and the base member 12 are fixed by forming a joint 17 formed by melting frit glass.

  As described above, the reason for adopting the heater structure in which the arc tube and the arc tube and the base member for sealing which is a separate member are integrated is as follows. First, it seems that a structure in which the end of the arc tube is sealed by a conventionally known means such as a pinch seal to ensure the airtightness of the heater is possible, but sapphire, which is the arc tube constituent material, is high. This is because it is difficult to adopt a pinch seal structure in an arc tube made of sapphire due to having a melting point. Secondly, the base member is fixed so that it can be expanded and contracted to some extent in the tube axis direction when the heating element is thermally expanded, and is sufficiently filled with a carbon wire member for supplying power to the heating element. However, the arc tube made of sapphire is processed so as to have such a space, specifically, the shape corresponding to the space filled with the carbon wire member has a large diameter. This is because it is extremely difficult.

  The heating element 13 is a carbon wire heating element such as a braided string of about 2 mm in diameter or braided using about 9 bundles of about 3000 to 3500 carbon single fiber fibers having a diameter of 5 μm to 15 μm. Is the body. Such a carbon wire heating element has a small heat capacity and excellent temperature rising / falling characteristics as compared with a solid heating element made of a conventional metal material, and is also excellent in high temperature durability in a non-oxidizing atmosphere.

The base member 12 is a disc-shaped closing member 15 made of alumina by frit glass same as the joining portion 17 in order to ensure the airtightness of the heater 1 at the end opposite to the side where the arc tube 11 is joined. Is installed. In the through hole provided in the vicinity of the center of the closing member 15, an exhaust pipe 16 for sealing an inert gas (described later) inside the arc tube 11 and the base member 12 is fixed by frit glass.
The exhaust pipe 16 is connected to a power source (not shown) and needs to have conductivity to play a role of supplying power to the heating element 13 and has a thermal expansion coefficient close to that of alumina constituting the closing member 15. Preferably, it is made of niobium, and is fixed in a compressed state in a wire carbon member 14 that is compressed and housed in the internal space of the base member 12. The exhaust pipe 16 seals the end portion protruding outward from the base member 12 after sealing with an inert gas in order to ensure the hermeticity of the heater. Is illustrated.
The wire carbon member 14 is preferably made of the same material as the carbon wire heating element constituting the heating element 13 and has the same structure.

As shown in FIG. 2, the cylindrical conductive member 18 extends along the tube axis direction and covers the outer periphery of the portion corresponding to the joint portion 17 that joins the arc tube 11 and the base member 12 in the heating element 13. The one end is fitted and fixed between the outer surface of the heating element 13 and the inner surface of the arc tube 11, and the other end is the end of the arc tube 11 along the outer surface of the heating element 13. It is compressed and fixed in the wire carbon member 14 which protrudes from the portion and is compressed and accommodated in the internal space of the base member 12. The conductive member 18 can reduce the electrical resistance in the vicinity of the joint 17 in the heating element 13, so that the joint 17 can be prevented from being in a high temperature state.
The conductive member only needs to reduce the electric resistance of the heating element by increasing the current passage area. For example, a rod-shaped member can be used instead of the cylindrical member as described above.

  The conductive member 18 is preferably made of a material having high conductivity and excellent high-temperature durability because it is necessary to reduce the electrical resistance of the heating element 13, for example, carbon, silicon carbide (SiC), titanium. (Ti), molybdenum (Mo), and the like. In particular, carbon is preferable because it is inexpensive and has good workability. The conductive member 18 has a total length (tube axis direction) of 10 mm to 50 mm, for example, 40 mm, and a thickness of 0.1 mm to 0.9 mm, for example, 0.3 mm.

Here, the reason why the current passage area in the heating element 13 must be increased by the conductive member 18 is as follows.
That is, the joint 17 between the arc tube 11 and the base member 12 is such that the arc tube 11 and the base member 12 are joined in the tube axis direction by a predetermined means, and the heating element 13 is wire carbon for power supply. Due to the fact that it is necessary to embed in the member 14, the structure must be close to the heating element 13 serving as a heat source. In this case, the frit glass constituting the joint 17 is the heating element. This is because the problem of melting by receiving heat from 13 occurs.

  In the heater 1 in which the arc tube 11 and the base member 12 are integrated, an inert gas such as nitrogen gas, argon gas, or helium gas is passed through the exhaust pipe 16 in order to prevent oxidation of the heating element 13. Gas is enclosed. The heater 1 is driven by supplying power to the heating element 13 via the wire carbon member 14 electrically connected to the exhaust pipe 16 by supplying power to the exhaust pipe 16 by a power source (not shown). The

According to the heater of the present invention as described above, the arc tube is made of a material excellent in high temperature durability such as sapphire, for example, thereby satisfying an extremely high temperature condition required in a semiconductor manufacturing process, for example. Therefore, even when a large amount of electric power is applied and the heating element is brought to a high temperature state, there is a problem that the heating element is oxidized due to melting of the material constituting the arc tube and impairing the hermeticity of the heater. It can be surely prevented from occurring. Furthermore, a predetermined length is provided between the heating element 13 and the arc tube 11 so as to cover at least the vicinity of the portion corresponding to the joint portion 17 joining the arc tube 11 and the base member 12 in the heating element 13. Due to the interposition of the conductive member 18 as the electric resistance reducing portion, the increase in the temperature of the joint portion 17 is suppressed due to the reduction in the electric resistance of the heating element 13 at the location where the conductive member 18 is provided. Accordingly, there is no possibility that the frit glass constituting the joint portion 17 is melted, and therefore it is possible to reliably prevent the occurrence of the problem that the heating element 13 is oxidized as the joint portion 17 melts.

  On the other hand, according to a heater equipped with a conventional arc tube made of quartz glass, when a large amount of power is supplied to the heating element to satisfy a high temperature condition, the quartz glass that is the arc tube constituent material is melted. When the airtightness of the heater is impaired, there is a problem that the heating element is exposed to the atmosphere and oxidized.

  In addition, the present invention is not provided with an electrical resistance reducing means (conductive member 18) between the heating element and the arc tube, which the present inventor made and evaluated in the process up to the completion of the present invention. In the heater having the same structure as that of FIG. 1, the frit glass that joins the arc tube and the base member is melted so that the hermeticity of the heater is lost. Has been found to cause the problem of oxidation when exposed to the atmosphere.

FIG. 3 is an enlarged cross-sectional view of a main part of a heater according to another embodiment of the present invention. 1 and 2 denote the same parts.
As shown in FIG. 3, in the heater 2, the arc tube 11 made of sapphire and the base member 12 made of a conductive material, for example, Kovar (Fe—Ni—Co alloy) correspond to the joint portion 17 in advance. Joining is performed by brazing in the metallization processing portion performed on the outer surface of sapphire, and a joining portion 17 made of a brazing material such as silver brazing is formed. A disc-shaped closing member 15 is fitted into the end of the base member 12 opposite to the side connected to the arc tube 11. That is, the heater 3 does not include a member corresponding to the exhaust pipe 16 illustrated in FIG. 1, and an inert gas is used to prevent oxidation of the heating element 13 through the base member 12 and into the arc tube 11 and the base member 12. After the sealing, the closing member 15 may be fitted and fixed. Except for these structures, the other structures are the same as those of the heater 1 shown in FIG.

  Since the base member 12 is made of a conductive material, the heater 2 is driven by connecting the base member 12 to a power source (not shown) and supplying power to the heating element 13 via the base member 12.

  The heater 2 does not have a structure corresponding to an exhaust pipe, and the inert gas is sealed directly inside the arc tube 11 and the base member 12 through the base member 12, and the base member 12 made of a conductive material is provided. In this case, the number of components can be reduced by one, so that in addition to the effects obtained with the heater 1 shown in FIG. It has the effect of becoming advantageous.

FIG. 4 is an enlarged cross-sectional view of a main part of a heater according to another embodiment of the present invention. 1 and 2 denote the same parts.
The heater 3 includes an arc tube 11 made of sapphire, and a cylindrical base member 12 made of, for example, Kovar as a conductive material. Each end of the arc tube 11 is fitted into one end of the arc tube 11 and joined to the arc tube 11. And both ends of the arc tube 11 and the base member 12 project outward from the base member 12 and along the tube axis direction of the arc tube 11 so as to be disposed in the exhaust pipe 16 to be described later. And a heating element 13 arranged. The arc tube 11 and the base member 12 are fixed by forming a joint portion 17 by brazing with, for example, silver brazing, in a metallization processing portion previously applied to the outer surface of the sapphire corresponding to the joint portion 17. The other end of the base member 12 is fitted with an arc tube 11 and an exhaust pipe 16 for sealing an inert gas inside the base member 12, and is fixed by a predetermined means such as brazing with silver brazing. .

  The exhaust pipe 16 is in contact with the heating element 13 at a reduced diameter portion 161 formed at an arbitrary position in the pipe axis direction, thereby fixing the heating element 13 so as not to move in the pipe axis direction. It is characterized in that it is electrically connected to the heating element 13.

  According to the heater 3, the exhaust pipe 16 is electrically connected to the heating element 13 at the reduced diameter portion 161 formed in a part thereof, so that the heater 1 and the heater 2 shown in FIGS. As shown in FIGS. 1 and 2, since the wire carbon member and the blocking member are not provided, and the heating element 13 can be fed through the exhaust pipe 16 only by a power source (not shown) connected to the exhaust pipe 16. As a result of the simplified structure compared to the heater 1 and the heater 2 shown, in addition to the effect obtained by the heater 1 shown in FIG. 1, there is an effect that productivity is improved and cost is advantageous.

The heater of this invention is not limited to said embodiment, A various change can be added.
For example, in the heater of the present invention, the arc tube 11 is not limited to sapphire, but can be composed of polycrystalline alumina, mullite (Al ₂ O ₃ .SiO ₂ ), zirconia, magnesia, or the like.

  Further, the method of expanding the current passage area at the portion corresponding to the joint 17 of the heating element 13 is not limited to providing the conductive member 18 separate from the heating element 13. Processing can also be performed so that the diameter at the corresponding location is larger than that at the location away from the joint 17, for example, the central portion.

  Further, in the heater 1 and the heater 2 shown in FIGS. 1 and 2, it is not an essential condition to fill the base member 12 with the wire carbon member 14, and the heating element 13 and the exhaust pipe 16 or The base member 12 can also be electrically connected.

  Hereinafter, experimental examples performed for confirming the effects of the present invention will be described.

〔Example〕
A plurality of heaters 1 according to the present invention were produced according to the structure shown in FIG. A specific configuration of the heater 1 is as follows.
The heating element 13 is a braided carbon wire heating element using nine bundles of fiber bundles of 350 carbon single fiber fibers having an outer diameter of 1.8 mm, a total length of 1050 mm, and a diameter of 10 μm.
The arc tube 11 is made of sapphire, and is a straight tube having an outer diameter of 5 mm, an inner diameter of 2 mm, and a total length of 1060 mm.
The base member 12 is made of alumina and has an outer diameter of 8 mm, an inner diameter of 6 mm, and a total length of 47 mm.
The exhaust pipe 16 is made of niobium, has an outer diameter of 3 mm, an inner diameter of 2 mm, and a total length of 37 mm.
The conductive member 18 is made of carbon and has an outer diameter of 1.95 mm, an inner diameter of 1.35 mm, and a total length of 40 mm.

  When the plurality of manufactured heaters 1 were confirmed by driving each heating element 13 so that the temperature of the heating element 13 became 1200 ° C., the arc tube 11 and the arc tube 11 and the base member 12 were joined in all the heaters. It was confirmed that the joining part 17 did not melt and the heat generating element 13 did not fail to oxidize. In addition, the heating element 13 is red-heated near the center and is in a high temperature state, whereas the portion where the conductive member 18 is provided is black without the heating element being red-hot, and is in a relatively low temperature state. It was confirmed that

[Comparative Example]
A plurality of heaters having the same configuration as in the above example except that the conductive member 18 was not provided were manufactured.

  When the plurality of heaters thus manufactured were checked by driving the heating element 13 so that the temperature of the heating element 13 became 1200 ° C., in some heaters, the joint portion 17 joining the arc tube 11 and the base member 12. (Frit glass) melted, and accompanying this, there was a problem that the heating element 13 was oxidized. Moreover, it was confirmed that the whole heat generating body 13 became red and became a high temperature state.

It is a figure for demonstrating the heater of this invention. It is a principal part enlarged view of the heater of this invention. It is a figure for demonstrating other embodiment which concerns on the heater of this invention. It is a figure for demonstrating other embodiment which concerns on the heater of this invention.

Explanation of symbols

Reference Signs List 1 heater 11 arc tube 12 base member 13 heating element 14 wire carbon member 15 closing member 16 exhaust pipe 17 joint 18 conductive member

Claims (8)

An arc tube made of a ceramic material, in which a heating element formed of carbon is disposed, and a base member joined to both ends of the arc tube,
The heater according to claim 1, wherein the heating element includes an electric resistance reducing unit for reducing the electric resistance at least at a location corresponding to a joining location between the arc tube and the base member. The heater according to claim 1, wherein the arc tube is made of sapphire. The heater according to claim 2, wherein the base member is made of an insulating material and joined to the arc tube by frit glass. The heater according to claim 2, wherein the base member is made of a conductive material and is joined to the arc tube by brazing. The heater according to claim 1, wherein the electrical resistance reduction unit is made of a conductive member. The heater according to claim 5, wherein the conductive member is made of carbon. The heater according to claim 1, wherein the heating element is compressed and fixed to a wire carbon member filled in the base member and is electrically connected to the wire carbon member. The base member is connected to an exhaust pipe made of a conductive material at an end opposite to the side connected to the arc tube, and the exhaust pipe has the heating element at a reduced diameter portion formed in a part thereof. The heater according to claim 1, wherein the heater is electrically connected to the heater.

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