JP5347319B2 - Vertical heat treatment equipment - Google Patents

Description

  The present invention relates to a vertical heat treatment apparatus for performing heat treatment on a substrate such as a semiconductor wafer.

  After a wafer is cut out from a single crystal ingot such as semiconductor single crystal silicon, a number of steps are involved from the wafer processing process to the element formation process until a semiconductor device is manufactured. One of these processes is a heat treatment process. This heat treatment step is performed for the purpose of forming a defect-free layer on the wafer surface layer, forming a gettering layer by forming oxygen precipitates, forming an oxide film, and diffusing impurities, and is a very important process.

As a heat treatment apparatus used in such a heat treatment process, for example, a diffusion furnace (oxidation / diffusion apparatus) used for oxidation and impurity diffusion, a plurality of wafers are stacked in a state of being horizontally stacked as the wafer diameter increases. A vertical heat treatment apparatus for simultaneously heat-treating these wafers is mainly used.
In this vertical heat treatment apparatus, a heat treatment boat for holding a plurality of wafers is usually used. Such a heat treatment apparatus that performs heat treatment on a plurality of wafers at the same time is called a batch-type heat treatment furnace.

FIG. 4 is a schematic view showing an example of a conventional batch type vertical heat treatment apparatus. As shown in FIG. 4, the reaction chamber of the heat treatment apparatus 101 is formed by a reaction tube 102 made of quartz, and a heat treatment boat 103 on which a heat treatment substrate W such as a silicon wafer is placed is installed. A quartz gas introduction pipe 104 for supplying atmospheric gas such as H ₂ , O ₂ , N ₂ , Ar, etc. into the reaction chamber is welded to the upper part of the reaction pipe, and this gas introduction pipe 104 is not shown in the figure. Connected to the supply source. Furthermore, a silicon carbide (SiC) liner tube 105 is installed so as to surround the reaction tube 102 and the gas introduction tube 104. A heater 106 is installed outside the liner tube 105, and the substrate W to be processed placed on the heat treatment boat 103 is heated by the heater 106.

  However, when high-temperature heat treatment such as 1200 ° C. is performed using such a vertical heat treatment apparatus 101, the reaction tube 102 made of quartz is deformed by heat, and the reaction tube 102 is heat-treated boat 103 or liner tube. There was a problem of contact with 105 and damage.

  An example of a vertical heat treatment apparatus for preventing deformation of the reaction tube 102 is described in Patent Document 1. This is a vertical heat treatment apparatus 101a as shown in FIG. 5, and the reaction tube 102 is made of silicon carbide having high heat resistance instead of quartz. In this case, since the quartz gas introduction tube 104 cannot be welded to the reaction tube 102, a quartz flange 107 is provided below the vertical heat treatment apparatus 101 a, that is, below the reaction tube 102. It is necessary to weld the gas introduction pipe 104 made of quartz, insert the gas introduction pipe 104 into the reaction chamber from the lower part of the vertical heat treatment apparatus 101a, and extend the gas introduction pipe 104 to the upper part in the reaction chamber.

  Therefore, the SiC gas pipe 104a is connected to the quartz gas introduction pipe 104 in the reaction chamber. However, air leaking from the gap between the reaction pipe 102 and the quartz flange 107 in the upper part of the vertical heat treatment apparatus 101a is formed. There has been a problem that the gas pipe 104a enters the inside of the gas pipe 104a through the connection portion between the gas introduction pipe 104 and the gas pipe 104a, and the air is supplied to the wafer during the heat treatment, causing the wafer surface to be fogged.

Japanese Patent Application No. 2007-282941

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is a vertical type that suppresses thermal deformation of the reaction tube due to heat treatment and does not cause the wafer to cloud due to leakage. It is to provide a heat treatment apparatus.

To achieve the above object, the present invention provides at least a quartz reaction tube, a heat treatment boat disposed in the reaction tube for holding the substrate to be processed, and a heater for heating the substrate to be processed. The reaction tube has a cylindrical body portion and a ceiling portion, and a reaction for supporting the reaction tube and suppressing thermal deformation is provided inside the reaction tube. that provides a vertical heat treatment apparatus, wherein the tubular support is one that is placed.

As described above, if the vertical heat treatment apparatus in which the reaction tube support for supporting the reaction tube and suppressing the thermal deformation is arranged inside the reaction tube made of quartz, the reaction tube made of quartz is Even if softened by heat, the reaction tube support can support the quartz reaction tube to minimize deformation. For this reason, it is possible to prevent a conventional problem that the reaction tube which is largely thermally deformed contacts the heat treatment boat or the liner tube.
Therefore, even though the reaction tube is made of quartz, it can be used even in high temperature annealing. Moreover, since the life of the quartz reaction tube can be extended, the cost of the reaction tube can be reduced and the operating rate can be improved. Furthermore, since the reaction tube is made of quartz, there is no concern about leakage of the seam unlike the reaction tube made of SiC.

At this time, the reaction tube support is made of silicon carbide, silicon carbide with a silicon carbide CVD coat, carbon with a silicon carbide CVD coat, silicon, silicon with silicon carbide although the CVD coating has been applied and even have preferred either.
If the material of the reaction tube support is one of these, it is highly heat resistant and can more effectively suppress deformation of the quartz reaction tube due to heat, and also contaminate the substrate to be treated with heavy metals and other impurities. The vertical heat treatment apparatus can be reduced.

Further, the reaction tube support has a cylindrical body portion, and the outer diameter of the body portion may be 90% or more and less than 100% of the inner diameter of the body portion of the reaction tube. The
As described above, the outer diameter of the body portion of the reaction tube support is 90% or more and less than 100% of the inner diameter of the reaction tube body portion. The deformation of the reaction tube can be further reduced.

At this time, the reaction tube support is the has a top portion for supporting the ceiling portion of the reaction tube further top panel section has preferably that is made of a flat plate or a curved plate.
If it is such, the ceiling part of a reaction tube can be supported and the deformation | transformation of the ceiling part of a reaction tube can also be suppressed to the minimum.

The reaction tube support is connected to the top portion for supporting the ceiling portion of the reaction tube made of any one of a frame, a flat plate, and a curved plate, a bottom portion made of the frame, and the top portion and the bottom portion. and, Ru can be made to have a plurality of struts for supporting the body of the reaction tube.
If it is such, it will be possible to support the ceiling portion of the reaction tube, can suppress deformation of the ceiling portion, and further has a plurality of support columns for supporting the body portion of the reaction tube. Therefore, it is lightweight and easy to handle, and the manufacturing cost can be reduced.

At this time, it is preferable that the outer diameter of the top portion made of any one of the frame, the flat plate, and the curved plate of the reaction tube support is 90% or more and less than 100% of the inner diameter of the ceiling portion of the reaction tube. better not.
If it is such, the space of the reaction chamber will not be narrowed more than necessary, and the deformation of the ceiling of the reaction tube due to heat can be further reduced.

  With the vertical heat treatment apparatus of the present invention, the reaction tube support can suppress thermal deformation of the reaction tube. As a result, while the reaction tube is made of quartz, it can be used for high-temperature annealing, and the life of the reaction tube can be extended to reduce the cost and improve the operating rate. Further, since the reaction tube is made of quartz, the seam can be welded, so there is no risk of leakage.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.
Conventionally, when a heat treatment at a high temperature such as 1200 ° C. is performed using a vertical heat treatment apparatus 101 as shown in FIG. 4, the reaction tube 102 made of quartz is deformed by heat, and the reaction tube 102 is transformed into a heat treatment boat. There was a problem that the contact with 103 and the liner tube 105 was damaged.

  When the vertical heat treatment apparatus 101a as shown in FIG. 5 is used, the air leaking from the gap between the reaction tube 102 of the vertical heat treatment apparatus 101a and the quartz flange 107 is made of the quartz gas introduction pipe 104 and the SiC product. There is a problem that the gas pipe 104a enters into the gas pipe 104a from the connecting portion of the gas pipe 104a, and the air is supplied to the wafer being heat-treated, causing the wafer surface to be clouded.

  Therefore, the present inventor conducted intensive research on this vertical heat treatment apparatus, and in order to suppress deformation of the quartz reaction tube due to heat, if the reaction tube support is arranged in the reaction tube, the quartz It has been found that even when the reaction tube starts to soften and deform due to heat treatment, the reaction tube support can support the reaction tube, and the degree of deformation of the reaction tube can be suppressed.

With such a configuration, it is possible to prevent the reaction tube 102 from being largely thermally deformed and contacting the heat treatment boat 103 and the liner tube 105 as in the vertical heat treatment apparatus 101 of FIG. Further, unlike the vertical heat treatment apparatus 101a of FIG. 5, it is not necessary to provide a quartz flange 107 or connect the SiC gas pipe 104a to the quartz gas introduction pipe 104, and the entire reaction tube can be made. By eliminating the joint with SiC and made of quartz, it is possible to prevent air leakage and further occurrence of fogging on the surface of the substrate to be processed.
The present inventor found these things and completed the present invention.

  FIG. 1 is a schematic view showing an example of a batch type vertical heat treatment apparatus according to the present invention. As shown in FIG. 1, a vertical heat treatment apparatus 1 according to the present invention includes a quartz reaction tube 2, a heat treatment boat 3 installed inside the reaction tube 2 and on which a substrate to be processed W is placed, A liner tube 5 surrounding the reaction tube 2 is provided. A heater 6 is installed around the liner tube 5, and the substrate to be processed W can be heated by the heater 6.

Each configuration will be described below.
The reaction tube 2 made of quartz has a cylindrical body portion 10 and a ceiling portion 11 at the upper end thereof.
The trunk portion 10 has a cylindrical shape and is not particularly limited as long as the heat treatment boat 3 can be disposed on the inner side, but is preferably a cylindrical shape. In FIG. 1, a cylindrical shape is taken as an example.
Moreover, the shape of the ceiling part 11 is not specifically limited, For example, it can also be made flat like a flat plate, and can also be made into the shape which has a curvature radius like a curved-surface board. A quartz gas introduction tube 4 for supplying atmospheric gas such as H ₂ , O ₂ , N ₂ , Ar, or the like to the inside of the reaction tube 2 during the heat treatment is welded to the ceiling portion 11. The welding position and the like of the gas introduction pipe 4 are not particularly limited, but the atmospheric gas can be efficiently supplied into the reaction pipe 2 as long as it is the center part of the ceiling part 11. Further, the number is not limited to one, and a necessary number can be provided as appropriate. The gas introduction tube 4 passes between the reaction tube 2 and the liner tube 5, and the other end is connected to a gas supply source (not shown). As described above, in the present invention, since the reaction tube 2 is made of quartz, the joint of the gas introduction tube 4 and the like can be welded together by welding between quartzs, so that a leak such as a connection between quartz and SiC does not occur.

  A reaction tube support 12 is disposed inside the reaction tube 2. The reaction tube support 12 is for suppressing the quartz reaction tube 2 from being thermally deformed by heat treatment, and can support the reaction tube 2 from the inside of the reaction tube 2 that is thermally deformed. The material, shape, etc. are not particularly limited. In each case, an appropriate one according to the heat treatment conditions can be prepared.

  For example, regarding the material, any of silicon carbide, silicon carbide with silicon carbide CVD coating, carbon with silicon carbide CVD coating, silicon, silicon with silicon carbide CVD coating It can consist of These materials, particularly those using silicon carbide, have high heat resistance and are suitable for supporting a quartz reaction tube 2 that is thermally deformed, and the degree of thermal deformation of the reaction tube 2 is more effectively reduced. In addition, a vertical heat treatment apparatus with little contamination of impurities such as heavy metals on the substrate W can be obtained.

  Further, as shown in FIG. 1, the reaction tube support 12 has a body portion 13 for supporting the body portion 10 of the reaction tube 2 to be deformed, and the body portion 13 is the reaction tube 2. The same cylindrical shape (in the case of FIG. 1, a cylindrical shape) as that of the body portion 10 is mentioned. And the outer diameter of this trunk | drum 13 can be made into 90 to 100% of the internal diameter of the trunk | drum 10 of the reaction tube 2, for example. With such a shape and a reaction tube support in the above range, the space in the reaction chamber is not unnecessarily narrowed when arranged inside the reaction tube 2. Furthermore, since it can arrange | position in the vicinity along the inner wall of the reaction tube 2, even if the reaction tube 2 is thermally deformed, it is possible to support the reaction tube 2 while the degree of deformation is small. That is, it is possible to effectively prevent the reaction tube 2 from being largely thermally deformed until it comes into contact with the heat treatment boat 3 disposed inside and the liner tube 5 disposed outside as in the prior art.

  At this time, the reaction tube support 12 may have a top portion 14 for supporting the ceiling portion 11 of the reaction tube 2 at the upper end thereof. The top portion 14 can be formed into a flat shape (flat plate 15) as shown in FIG. 1, for example. The top portion 14 is provided with a through hole 17 for inserting the gas introduction pipe 4.

In addition to the flat plate 15 as shown in FIG. 1, the top portion 14 of the reaction tube support 12 may be constituted by a curved plate 16 as in another example of the vertical heat treatment apparatus of the present invention shown in FIG. 2. Is possible. The shape and constituent members of the top part 14 are not particularly limited, and an appropriate shape can be selected in accordance with the shape of the ceiling part 11 of the reaction tube 2.
It should be noted that the upper end of the reaction tube support 12 is not provided with the flat plate 15 or the curved plate 16 and can be opened, but the one having the top portion 14 as shown in FIGS. 1 and 2 is better. It is preferable because the thermal deformation of the ceiling portion 11 of the reaction tube 2 can be more appropriately supported.

  In addition, regarding the shape of the reaction tube support, for example, the one shown in FIG. The reaction tube support 12a shown in FIG. 3 includes a frame 19 on each of the top portion 14a at the upper end and the bottom portion 18 at the lower end, and is constituted by a plurality of columns 20 that connect these frame bodies 19. . With such a configuration, when the reaction tube 2 is thermally deformed, it is possible to support the ceiling portion 11 of the reaction tube 2 with the top portion 14 a and support the trunk portion 10 of the reaction tube 2 with the support column 20.

In addition, by configuring the frame 19 and the plurality of support columns 20 in this way, the reaction tube support 12a can be reduced in weight and can be handled easily. In addition, the material cost can be kept low, and the structure can be reduced.
Note that the top portion 14a of the reaction tube support 12a is not limited to the frame body 19, but is a flat plate 15 or a curved plate 16 as shown in FIGS. It is also possible.

  Further, the outer diameter of the top portion 14a (circular in the case of FIG. 3) of the reaction tube support 12a is set to the inner diameter of the ceiling portion 11 of the reaction tube 2 (as can be seen from FIG. 3). 90% or more and less than 100%). By making the top part 14a of such a size and also adjusting the height of the support column 20 as appropriate, it can be arranged in the vicinity of the inner wall of the reaction tube 2, and the space of the reaction chamber is made narrower than necessary. In addition, the reaction tube 2 can be efficiently supported so as not to be largely thermally deformed.

  The reaction tube 2 and the reaction tube supports 12 and 12a as shown in FIGS. 1 to 3 are each provided with an exhaust port 21 at the lower portion, and the exhaust port 21 can react during heat treatment. It is possible to exhaust the atmospheric gas supplied to the room outside the system.

  Other configurations other than the above in the vertical heat treatment apparatus 1 of the present invention such as the heat treatment boat 3, the liner tube 5, and the heater 6 are not particularly limited, and can be the same as, for example, the conventional one. Depending on the size of the substrate to be processed, heat treatment conditions, etc., it is possible to prepare an appropriate one each time.

  If the vertical heat treatment apparatus of the present invention as described above, even if the quartz reaction tube is thermally deformed by heat treatment, it can be supported by the reaction tube support disposed on the inside, The reaction tube can be prevented from being greatly deformed by heat as in the prior art. By reducing the degree of thermal deformation, it is possible to prevent the reaction tube from contacting the heat treatment boat or the liner tube. In the first place, since the reaction tube support is arranged inside the reaction tube, that is, between the reaction tube and the heat treatment boat, it is particularly effective to prevent the body of the reaction tube from contacting the heat treatment boat. . For these reasons, high-temperature annealing can be performed while using a quartz reaction tube, and the life of the reaction tube can be extended. Therefore, the cost of the reaction tube can be reduced and the operating rate can be improved. Furthermore, since the reaction tube is made of quartz, the connection portion can be welded by welding, so there is no risk of leakage.

EXAMPLES Hereinafter, although this invention is demonstrated further in detail using an Example and a comparative example, this invention is not limited to this.
Example 1
A vertical heat treatment apparatus equipped with a cylindrical quartz reaction tube having an inner diameter of 380 mm and an outer diameter of 390 mm as shown in FIG. 1 was prepared. The ceiling portion of the reaction tube is a flat plate, and a gas introduction tube extending from the outside of the cylindrical body is welded to the center of the ceiling portion so as to supply atmospheric gas from the upper part of the reaction tube. An exhaust port is welded to the lower part of the body of the reaction tube. The periphery of the reaction tube is surrounded by a liner tube.
The reaction tube support further includes a body portion having a cylindrical shape having an outer shape of 370 mm and made of a material obtained by applying silicon carbide CVD coating to silicon carbide in the same tube shape as the body portion of the reaction tube. Arranged. The top of the reaction tube support is a flat plate, and a through hole is formed in the center of the flat plate for passing a gas introduction tube. The reaction tube support is arranged so that the clearance between the ceiling portion of the flat plate of the quartz reaction tube and the flat plate of the top of the cylindrical reaction tube support made of silicon carbide is 5 mm. A heat treatment boat was placed in the reaction tube and the reaction tube support, and the silicon single crystal wafer was heat-treated at 1200 ° C. for 1 hour 1000 times using such a vertical heat treatment apparatus of the present invention.

  The ceiling of the reaction tube is in contact with the top plate of the reaction tube support and the outer diameter of the reaction tube is expanded to a maximum of 400 mm, but the reaction tube is made of silicon carbide installed outside the heat treatment boat or reaction tube. The liner tube was not touched. Further, the heat-treated silicon single crystal wafer did not have a problem such as fogging which seems to be caused by leakage.

(Example 2)
The vertical heat treatment apparatus of the present invention (FIG. 2) similar to that of Example 1 except that the ceiling of the reaction tube is a dome-shaped curved plate with a radius of curvature of 500 mm and the top of the reaction tube support has a radius of curvature of 500 mm. And the same heat treatment as in Example 1 was performed.

  The ceiling made up of the curved plate of the reaction tube contacts the curved plate at the top of the reaction tube support, and the outer diameter of the reaction tube has expanded to a maximum of 400 mm, but the reaction tube is located outside the heat treatment boat or reaction tube. There was no contact with the installed liner pipe made of silicon carbide.

(Example 3)
A vertical heat treatment apparatus of the present invention shown in FIG. 3 was prepared.
The reaction tube is the same as in Example 1 except that the ceiling is a curved plate having a curvature radius of 500 mm.
The reaction tube support is composed of a pair of circular frames at the top and the bottom, and these pair of frames are connected by three columns having a width of 20 mm. This reaction tube support is made of a material obtained by applying silicon carbide CVD coating to silicon carbide, and the outer diameter of the top frame is 370 mm. When the reaction tube support is placed in the reaction tube, the gap between the ceiling made of a dome-shaped curved plate of the quartz reaction tube and the frame that is the top of the reaction tube support (here, the ceiling of the reaction tube) The distance between the frame body and the portion located immediately above the frame body in the part) was 5 mm. Using this vertical heat treatment apparatus, the same heat treatment as in Example 1 was performed.

  Although the ceiling portion made of the curved plate of the reaction tube was slightly dripped, it did not contact the heat treatment boat. Moreover, although the outer diameter of the reaction tube expanded to a maximum of 400 mm, it did not contact the silicon carbide liner tube installed outside the reaction tube.

(Comparative Example 1)
A vertical heat treatment apparatus as shown in FIG. 4 was prepared. That is, the reaction tube support in the vertical heat treatment apparatus of the present invention is not provided. The reaction tube is the same as in Example 1.
Using such a conventional vertical heat treatment apparatus, heat treatment was performed 500 times at 1200 ° C. for 1 hour.

  Despite the fact that the number of heat treatments was only half that of Example 1, the ceiling portion made of a flat plate of the reaction tube drastically dropped into a mortar shape, and contacted the heat treatment boat disposed in the reaction tube. In addition, the outer diameter of the reaction tube was increased to a maximum of 415 mm, and contacted with the silicon carbide liner tube installed outside the reaction tube, it could not be removed.

(Comparative Example 2)
A vertical heat treatment apparatus similar to Comparative Example 1 was prepared except that the ceiling of the reaction tube was a dome-shaped curved plate with a curvature radius of 500 mm.
Using such a conventional vertical heat treatment apparatus, heat treatment was performed 500 times at 1200 ° C. for 1 hour.

  The ceiling made of the dome-shaped curved plate of the reaction tube was slightly dripped but did not contact the heat treatment boat. However, the outer diameter of the reaction tube expanded to a maximum of 415 mm, and contacted with a silicon carbide liner tube installed outside the reaction tube, it could not be removed.

  As can be seen from the above Example 1-3 and Comparative Example 1-2, Example 1-3 using the vertical heat treatment apparatus of the present invention is different from Comparative Example 1-2 using the conventional vertical heat treatment apparatus. Despite the fact that the number of heat treatments is doubled, the degree of deformation of the reaction tube made of quartz is suppressed, and the reaction tube support is supported from the inside by the reaction tube support, and contacts the heat treatment boat and liner tube. It was possible to prevent problems from occurring. That is, with the vertical heat treatment apparatus of the present invention, the life of the reaction tube can be extended as compared with the conventional product, and the cost can be reduced and the operating rate can be improved.

  In addition, in the product of the present invention, unlike a vertical heat treatment apparatus having a SiC reaction tube as shown in FIG. 5, it is not particularly necessary to connect different tubes in the reaction tube when introducing the atmospheric gas. Intrusion of air from the connection portion of the tube can be prevented, and fogging on the surface of the substrate to be processed after heat treatment can be prevented.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

In the above embodiment, a reaction tube support made of silicon carbide with a silicon carbide CVD coating was used, but other materials such as silicon carbide and carbon with silicon carbide CVD coating were used. It is also possible for silicon, silicon, or silicon carbide to have a CVD coating of silicon carbide. These may be appropriately selected and used according to the heat treatment temperature, the type of substrate to be treated, and the like.
Further, the shape of the reaction tube support is not limited to the above example. Any vertical heat treatment apparatus provided with a reaction tube support that supports the reaction tube and suppresses thermal deformation thereof can be selected, and an appropriate reaction tube support can be selected according to the heat treatment conditions and the like. The same effect as the example can be obtained.

It is the schematic which shows an example of the vertical heat processing apparatus of this invention. It is the schematic which shows an example of the vertical heat processing apparatus of this invention whose ceiling part of a reaction tube and the top part of a reaction tube support body are curved plates. It is the schematic which shows an example of the vertical heat processing apparatus of this invention which a reaction tube support body consists of a pair of frame and several support | pillars. It is the schematic which shows an example of the conventional vertical heat processing apparatus. It is the schematic which shows an example of the conventional vertical heat processing apparatus provided with the reaction tube made from SiC.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Vertical heat processing apparatus in this invention, 2 ... Reaction tube, 3 ... Boat for heat processing,
4 ... Gas introduction pipe, 5 ... Liner pipe, 6 ... Heater,
10 ... trunk, 11 ... ceiling, 12, 12a, ... reaction tube support,
13 ... trunk part, 14, 14a ... top part, 15 ... flat plate, 16 ... curved plate,
17 ... through hole, 18 ... bottom, 19 ... frame, 20 ... support,
21: Exhaust port, W: Substrate to be processed.

Claims (3)

A vertical heat treatment apparatus having at least a quartz reaction tube, a heat treatment boat disposed in the reaction tube for holding the substrate to be processed, and a heater for heating the substrate to be processed,
The reaction tube has a cylindrical body portion and a ceiling portion, and a reaction tube support for supporting the reaction tube and suppressing thermal deformation is disposed inside the reaction tube ,
The reaction tube support is connected to the top portion for supporting the ceiling portion of the reaction tube made of any one of a frame, a flat plate, and a curved plate, a bottom portion made of a frame, and the top portion and the bottom portion. A vertical heat treatment apparatus comprising a plurality of support columns for supporting the body portion of the reaction tube.   The reaction tube support is made of silicon carbide, silicon carbide having a silicon carbide CVD coating, carbon having a silicon carbide CVD coating, silicon, silicon having a silicon carbide CVD coating. The vertical heat treatment apparatus according to claim 1, wherein the vertical heat treatment apparatus is one of those applied. The outer diameter of the top portion consisting of any of the frame body of the reaction tube support plates, curved plates, wherein wherein said is of less than 90% to 100% of the inner diameter of the ceiling portion of the reaction tube The vertical heat treatment apparatus according to claim 1 or 2 .

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