JP2009059844A - Heat treatment furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat treatment furnace capable of manufacturing an anneal wafer without degrading productivity and free from cracks on a quartz-made process tube even if a semiconductor substrate is heat-treated in an atmosphere of Ar, hydrogen or their mixture gas. <P>SOLUTION: The heat treatment furnace has the quartz-made process tube for heat-treating at least the semiconductor substrate in an atmosphere of Ar, hydrogen or their mixture gas. The process tube has a process tube body, a gas inlet pipe and a gas exhaust pipe. The heat treatment furnace further includes a detachable cover member fitted from the inside of the body into the gas exhaust pipe. The cover member has a cylinder having an outer diameter smaller than an inner diameter of the gas exhaust pipe and inserted into the gas exhaust pipe, and a flange having an outer diameter extending on one end of the cylinder, which is larger than the inner diameter of the gas exhaust pipe. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a heat treatment furnace having a quartz process tube for performing heat treatment of a semiconductor substrate (hereinafter also referred to as a wafer) in an atmosphere of Ar, hydrogen, or a mixed gas thereof.

Heat treatment (annealing) in an atmosphere of Ar, hydrogen, or a mixed gas thereof is used in a process of eliminating crystal defects near the surface of a semiconductor substrate, for example, a silicon wafer.
As a heat treatment furnace in which this kind of heat treatment process is performed, for example, a vertical heat treatment furnace 101 as schematically shown in FIG. 5 is known.

  FIG. 5 shows an example of a general vertical heat treatment furnace. The heat treatment furnace 101 includes a heater 102 arranged concentrically, a SiC soaking tube 103 and a quartz process tube 104 arranged inside, a boat 105 on which a plurality of semiconductor substrates W to be heat-treated are placed, A heat insulating cylinder 106 on which the boat 105 is detachably mounted, a lid 108 at the bottom thereof for closing the furnace port 107 at the lower end of the quartz process tube 104 during heat treatment, the boat 105, the heat insulating cylinder 106, and the lid 108 Is composed of elevating means (not shown) that moves up and down toward the inside of the quartz process tube 104. Reference numeral 109 denotes a soaking zone.

  Here, the quartz process tube 104 includes a process tube main body 110 into which the semiconductor substrate W to be heat-treated held in the boat 105 is inserted, a gas introduction pipe 111 connected to the upper portion of the process tube main body 110, and a process. A gas exhaust pipe 112 connected to the lower part of the tube main body 110 is provided.

  In performing heat treatment using such a heat treatment furnace 101, the semiconductor substrate W to be heat-treated is placed on the boat 105, the boat 105 is inserted into the process tube main body 110 by the elevating means, and the semiconductor substrate W is heated by the heater 102. Heat treatment is performed. Further, during this heat treatment, Ar, hydrogen, or a mixed gas thereof is introduced from the gas introduction pipe 111 into the process tube main body 110, while the gas introduced into the process tube main body 110 is introduced into the gas exhaust pipe 112. Exhaust outside the system.

  Now, when the heat treatment furnace having the quartz process tube is used as described above and the semiconductor substrate is annealed using Ar or hydrogen gas, the surface of the quartz process tube is etched in a small amount because of heat treatment at a high temperature. The In addition, the process gas is heated when entering the furnace, but the vicinity of the furnace port of the process tube main body is out of the soaking area, so that the gas reaching the vicinity of the furnace port is cooled. At that time, the SixOy etched simultaneously with the cooled process gas is also cooled.

  When cooled, for example, SixOy adheres to the lower inner wall surface and gas exhaust pipe in the process tube body. The SixOy is deposited as the number of treatments increases and grows as a thick film. The deposited SixOy film is subjected to great stress when the boat is taken in and out and the temperature is raised and lowered during the process, and the film peels off. Such a phenomenon leads to an increase in particle adhesion (particle contamination) to the wafer after annealing. In particular, SixOy tends to adhere to the lower inner wall surface and the gas exhaust pipe in the process tube body due to the gas flow. In order to avoid deposition of the SixOy film, it is necessary to frequently clean the quartz process tube. After the cleaning, the heat treatment furnace must be restarted, and the productivity of the annealed wafer is also reduced.

  Several techniques have been proposed for such problems. For example, Patent Literature 1, Patent Literature 2, and Patent Literature 3 disclose a heat treatment furnace in which a lower inner wall surface in a process tube main body and the periphery of a heat insulating cylinder are covered with a cylindrical removable cover member. According to these techniques, when the SixOy film is excessively deposited on the cover member, only the cover member may be removed from the process tube body and cleaned. Due to the presence of this cover member, the SixOy film deposited on the inner wall surface of the process tube body is greatly reduced, and it becomes possible to reduce the frequency of attaching and detaching the quartz process tube for cleaning, and the efficiency of annealing wafer production. Can be improved.

On the other hand, for the gas exhaust pipe, a technique for preventing clogging has been proposed. In Patent Document 4, a cladding tube having an outlet is inserted into a gas exhaust pipe through a buffer, and an adhesion preventing gas is introduced into the buffer. According to this technique, it is possible to prevent by-products and the like that are easily deposited from adhering to and depositing on the inner surface of the gas exhaust pipe and the cladding pipe.
In Patent Document 5, a cladding tube having an outlet is inserted into a part of an exhaust pipe system through a buffer, and byproducts are actively deposited on the cladding tube, and only the cladding tube is cleaned during maintenance. is there.
According to these techniques, it is possible to prevent the SixOy film from being deposited on the inner surface of the gas exhaust pipe.

  However, the above-described heat treatment furnaces of Patent Documents 1 to 5 show no improvement on the frequent cleaning of the quartz process tube to avoid the deposition of the SixOy film and the resulting decrease in the productivity of the annealed wafer. However, the life of the quartz process tube itself may be short, which is a problem. Further, there has been a problem in the productivity and cost of the annealed wafer in terms of the replacement frequency of the quartz process tube.

JP 2001-351873 A Japanese Patent Laid-Open No. 2003-1000076 JP 2005-216912 A JP 2004-104034 A JP 2005-158994 A

Then, the present inventors conducted extensive research on the quartz process tube of the heat treatment furnace, and found that the cause of the shortening of the life is the generation of cracks.
On the inner side surface of the gas exhaust pipe and the inner wall surface of the process tube body around the location where the gas exhaust pipe is connected (hereinafter, these may be referred to as a gas exhaust area), as described above, SixOy is caused by the gas flow. In addition to being easily attached, it is the place where the gas exhaust pipe is welded to the process tube main body, so that it is the weakest in the region where SixOy is deposited. The present inventors have found that cracks are generated due to stress caused by the deposited SixOy film. When cracks occur, metal contamination increases in the annealed wafer, or haze, which is a rough surface of the wafer, deteriorates. Therefore, it is necessary to replace the quartz process tube in which cracks have occurred, and naturally the productivity also decreases.
In the heat treatment furnace of Patent Document 1-5, in the gas exhaust region, a portion not covered with a cover member (in Patent Document 1-3, the inner surface of the gas exhaust pipe, and in Patent Document 4-5, a process near the gas exhaust pipe). The present inventors have found that cracks are generated in the inner wall surface of the tube body and the life of the quartz process tube is shortened.

  The present invention has been made in view of the above-mentioned problems. Even if the semiconductor substrate is heat-treated in an atmosphere of Ar, hydrogen, or a mixed gas thereof, the quartz process tube is not cracked, and the annealed wafer is obtained. An object of the present invention is to provide a heat treatment furnace that can be manufactured without reducing productivity.

In order to achieve the above object, the present invention is a heat treatment furnace having a quartz process tube for heat-treating at least a semiconductor substrate in an atmosphere of Ar, hydrogen, or a mixed gas thereof.
The quartz process tube was introduced into the process tube main body into which the semiconductor substrate to be heat-treated was inserted, and a gas introduction tube for introducing the Ar, hydrogen, or a mixed gas thereof into the process tube main body. A gas exhaust pipe for exhausting gas from the process tube body;
The heat treatment furnace further comprises a removable cover member that is inserted into the gas exhaust pipe from the inside of the process tube body,
The cover member has an outer diameter smaller than the inner diameter of the gas exhaust pipe, a cylindrical portion inserted into the gas exhaust pipe, and a flange portion having an outer diameter extending to one end of the cylindrical portion larger than the inner diameter of the gas exhaust pipe; A heat treatment furnace characterized by comprising: (Claim 1).

In such a heat treatment furnace according to the present invention, the outer diameter is smaller than the inner diameter of the gas exhaust pipe, the cylindrical portion inserted into the gas exhaust pipe, and the outer diameter extending to one end of the cylindrical portion is larger than the inner diameter of the gas exhaust pipe. Since the cover member having the flange portion is inserted into the gas exhaust pipe from the inside of the process tube main body, the inner surface of the gas exhaust pipe is particularly easy to adhere to the SixOy due to the gas flow and low in strength. , And the inner wall surface (gas exhaust region) of the process tube main body around the location where the gas exhaust pipe is connected is covered with the cover member. Thereby, SixOy adheres to the cover member, and it is possible to prevent SixOy from directly adhering to the gas exhaust region.
In addition, since the cover member is removable, it is possible to clean or replace only the cover member to which SixOy is adhered.

Therefore, in the gas exhaust region of the quartz process tube, it is possible to prevent the occurrence of cracks due to the stress caused by the directly deposited SixOy film, and the cover member can be replaced. If it is exchanged, it is possible to prevent cracks from occurring in the quartz process tube and to extend the life of the quartz process tube as compared with the conventional case. Thereby, the frequency of replacement due to the problem of the life of the quartz process tube is remarkably suppressed, and a time-consuming process such as replacement can be omitted, and the annealed wafer can be manufactured without reducing productivity.
In addition, since the occurrence of cracks can be prevented, an increase in metal contamination and haze deterioration can be extremely suppressed in the annealed wafer, and a high-quality annealed wafer can be obtained.

  Also, since it is a removable cover member, only the cover member can be cleaned, and if it is replaced at regular intervals, cleaning of the quartz process tube itself and restarting of the heat treatment furnace can be omitted. In this respect, the productivity of the annealed wafer can be prevented from being lowered, and SixOy is excessively deposited, and particle contamination caused by the peeling of the SixOy film can be easily prevented. Moreover, since the cover member is small and has a simple shape, the cover member is inexpensive and has great cost merit.

At this time, it is preferable that the cover member is made of quartz having a viscosity lower than that of quartz of the quartz process tube.
In this way, if the cover member is made of quartz having a lower viscosity than the quartz of the quartz process tube, the gas exhaust pipe into which the cover member of the quartz process tube is inserted is more effectively damaged. It can be prevented.

The cover member may be an oxyhydrogen flame molten product or a synthetic quartz product.
Thus, if the cover member is an oxyhydrogen flame melt or a synthetic quartz product, it can be made to contain a large amount of OH groups, and is made of high-purity quartz having a low viscosity.

  With the heat treatment furnace of the present invention, even if the semiconductor substrate is heat-treated in an atmosphere of Ar, hydrogen, or a mixed gas thereof, cracks can be prevented from occurring in the gas exhaust region of the quartz process tube, thereby The lifetime of the quartz process tube can be extended. As a result, a high-quality annealed wafer in which particle contamination, metal contamination, and haze deterioration are suppressed can be manufactured at low cost without reducing productivity.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.
As described above, when the semiconductor substrate is annealed using Ar, hydrogen, or a mixed gas thereof, the surface of the quartz process tube in the heat treatment furnace is slightly etched, and the etched SixOy is cooled downstream. In particular, it adheres to and accumulates on the gas exhaust region composed of the inner side surface of the gas exhaust pipe and the inner wall surface of the process tube main body around the connection portion of the gas exhaust pipe.

  This gas exhaust region is weakest in strength among the regions where SixOy adheres because the gas exhaust tube is welded to the process tube body of the quartz process tube. For this reason, the present inventors have found that cracks are likely to occur due to stress caused by the deposited SixOy film. Here, FIG. 6 shows an example of the occurrence of cracks in the gas exhaust region. As shown in FIG. 6, cracks occur at the base of the gas exhaust pipe 112 and around the connection portion of the gas exhaust pipe of the process tube main body 110. When cracks occur in this way, metal contamination increases in the annealed wafer or the haze on the wafer surface deteriorates, so that it becomes necessary to replace the quartz process tube in which the crack has occurred. As a result, the productivity of the annealed wafer decreases and the cost increases.

  The present inventors have found these problems, and furthermore, in solving these problems, as in Patent Document 1-5, only the inner surface of the gas exhaust pipe or the inside of the process tube main body around the connection portion of the gas exhaust pipe is used. Instead of providing a cover member for preventing the adhesion of SixOy only on the wall surface, it was considered necessary to simultaneously prevent the adhesion of SixOy in both of these regions.

Therefore, a removable cover member that is inserted into the gas exhaust pipe from the inside of the process tube main body, an outer diameter is smaller than an inner diameter of the gas exhaust pipe, and a cylindrical portion that is inserted into the gas exhaust pipe, and the cylindrical portion As long as the outer diameter of the gas exhaust pipe is larger than the inner diameter of the gas exhaust pipe, the inner surface of the gas exhaust pipe can be covered by the cylindrical portion, and the gas exhaust pipe is connected by the flange portion. The present inventors have found that the inner wall surface of the process tube body around the part can also be covered. That is, it is possible to simultaneously prevent direct adhesion of SixOy in both of the above-mentioned regions, which are particularly problematic when cracks occur, and to prevent cracks in the quartz process tube.
Moreover, since it is removable, only the cover member can be washed or replaced with another one after a certain period of use. That is, also from this point, not only the generation of cracks in the quartz process tube but also the breakage of the cover member itself can be prevented, so that the productivity reduction and the cost increase of the annealed wafer can be prevented.

In addition, it is possible to manufacture an annealed wafer without reducing productivity because the number of cleanings of the quartz process tube itself and the number of startups of the heat treatment furnace can be significantly reduced by replacing the cover member. it can.
The present inventors found these things and completed the present invention.

Hereinafter, the heat treatment furnace of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.
FIG. 1 is a schematic view showing an example of a heat treatment furnace of the present invention.
The heat treatment furnace 1 includes a heater 2 arranged concentrically, a SiC soaking tube 3 and a quartz process tube 4 arranged inside the boat, a boat 5 on which a plurality of semiconductor substrates W to be heat-treated are placed, and the boat A heat insulating cylinder 6 to which 5 is detachably attached, a lid body 8 at the bottom thereof for closing the furnace port 7 at the lower end of the quartz process tube 4 during heat treatment, the boat 5, the heat insulating cylinder 6 and the lid body 8 It consists of elevating means (not shown) that moves up and down toward the inside of the quartz process tube 4. Moreover, 9 has shown the soaking zone.
These parts are not particularly limited, and can be the same as, for example, the conventional one.

The quartz process tube 4 is connected to the process tube main body 10 into which the semiconductor substrate W to be heat-treated held in the boat 5 is inserted, and to the upper part of the process tube main body 10, and Ar, hydrogen, or these A gas introduction pipe 11 for introducing the mixed gas into the process tube main body 10 during heat treatment and a gas exhaust for exhausting the introduced gas from the process tube main body 10 are connected to the lower portion of the process tube main body 10. Tube 12.
The process tube main body 10, the gas introduction pipe 11, and the gas exhaust pipe 12 are not particularly limited, and may be the same as the conventional one.

The heat treatment furnace 1 of the present invention further includes a cover member 13 that can be removed from the inside of the process tube body 10. Here, the cover member 13 will be described in detail.
FIG. 2 shows an example of the cover member 13. FIG. 3 shows a state where the cover member is inserted into the gas exhaust pipe 12 from the inside of the process tube main body 10.
As shown in FIG. 2, the cover member 13 first has a shape having a cylindrical portion 14 and a flange portion 15 extending to one end thereof.
As shown in FIGS. 2 and 3, the outer diameter 14 do of the cylindrical portion 14 is smaller than the inner diameter 12 di of the gas exhaust pipe 12. Thereby, when the cover member 13 is inserted into the gas exhaust pipe 12, the cylindrical portion 14 can be inserted into the gas exhaust pipe 12.

  On the other hand, the flange portion 15 has an outer diameter 15do larger than the inner diameter 12di of the exhaust pipe 12. That is, when the cover member 13 is inserted into the gas exhaust pipe 12, the flange portion 15 is not inserted into the gas exhaust pipe 12, and is caught by the connection portion of the gas exhaust pipe 12 with the process tube body 10, The inner wall surface 10f of the process tube main body 10 around the connection portion of the gas exhaust pipe 12 can be covered.

  The length 141 of the cylindrical portion 14 of the cover member 13 is not particularly limited, and can be set as appropriate according to the diameter and length of the gas exhaust pipe 12. On the inner side surface 12f of the gas exhaust pipe 12, a range in which SixOy easily adheres and accumulates is investigated in advance, and can be set to a length that can cover the inner side surface 12f in the range.

  The size of the outer diameter 15do of the flange portion 15 of the cover member 13 is not particularly limited, and a range in which SixOy is likely to adhere and deposit on the inner wall surface 10f of the process tube body 10 around the connection portion of the gas exhaust pipe 12 is provided. It is possible to set the size so as to be able to cover the inner wall surface 10f in that range after investigation in advance.

The material of the cover member 13 is not particularly limited, but is preferably made of, for example, quartz having a lower viscosity than the quartz of the quartz process tube 4.
When the cover member is made of resin, it is not heat resistant and impurities may volatilize. Further, CVD-SiC may be used from the viewpoints of purity and heat resistance, but since the coefficient of thermal expansion is larger than that of quartz, there is a possibility that the gas exhaust pipe made of quartz may be damaged. On the other hand, if the high-purity quartz has a low viscosity as described above, the gas exhaust pipe 12 can be prevented from being damaged during use. As the quartz material having a low viscosity, an oxyhydrogen flame melted product or a synthetic quartz product containing a large amount of OH groups can be used.
Of course, it is not limited to these, and an appropriate thing can be prepared each time.

  In the heat treatment furnace 1 of the present invention provided with the cover member 13 as described above, the cover member 13 can be inserted into the gas exhaust pipe 12, and SixOy is particularly attached to the quartz process tube 4 during the heat treatment. The gas exhaust region to be deposited, that is, both the inner wall surface 10f of the process tube body 10 near the gas exhaust pipe 12 and the inner surface 12f of the gas exhaust pipe 12 can be covered simultaneously.

FIG. 4 is an explanatory view showing a state where SixOy is deposited on the cover member 13 in the heat treatment furnace 1 of the present invention. Even if the SixOy cooled on the downstream side during the heat treatment flows near the gas exhaust region. Since the gas exhaust region is covered by the cover member 13, SixOy adheres to the surface of the cover member 13 and directly adheres to the inner wall surface of the process tube body 10 and the inner surface of the gas exhaust pipe 12 in the gas exhaust region. Can be effectively prevented.
In addition, since the cover member 13 is removable, it can be used for a certain period of time and replaced with another one or cleaned after the SixOy has accumulated.

Therefore, with the heat treatment furnace 1 of the present invention, it is possible to prevent cracks from occurring in the gas exhaust region of the quartz process tube 4 due to the deposited SixOy film. As a result, the life of the quartz process tube 4 can be extended, and the time spent for the replacement or the like can be omitted. As a result, an annealed wafer can be manufactured at low cost without reducing productivity.
In addition, since cracks can be prevented, it is possible to prevent metal contamination from increasing in the annealed wafer and to prevent haze deterioration, and a high-quality annealed wafer can be obtained.

  If the removable cover member 13 is replaced or cleaned at regular intervals, the SixOy film deposited on the cover member 13 can be easily removed out of the system, particle contamination of the annealed wafer can be prevented, and the quartz process can be prevented. The frequency of cleaning the tube 4 itself can be remarkably suppressed. Therefore, it is possible to suppress a decrease in the productivity of the annealed wafer also from this point.

  On the other hand, in the conventional heat treatment furnace, even if a part of the gas exhaust region is covered with a cover member and the cover member is cleaned at regular intervals, as in Patent Document 1, etc., the gas that is not covered with the cover member in particular. In other parts of the exhaust region, SixOy directly adheres, cracks are generated, and the life of the quartz process tube is shortened. That is, the replacement frequency of the quartz process tube is increased, and the productivity and cost are deteriorated. Even in the annealed wafer, particle contamination, metal contamination, and haze deterioration occur.

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to this.
(Example 1)
A 12-inch (300 mm) diameter, p-type, 1-30 Ωcm semiconductor substrate is heat-treated in the heat treatment furnace of the present invention in which the cover member 13 shown in FIG. The heat treatment condition is Ar annealing at 1200 ° C. for 60 minutes.
Here, the material of the cover member used is made of synthetic quartz, and the size of each part will be described. The outer diameter of the cylinder part is 1.8 cm, and the outer diameter of the flange part is 6.0 cm. It is. Further, the inner diameter of the gas exhaust pipe into which the cylinder part is inserted is 2.0 cm, and the length of the cylinder part is 6.0 cm.

  After the heat treatment, the presence or absence of cracks in the gas exhaust region of the quartz process tube and the state of the deposited SixOy film were examined. The above processes are repeated a total of 300 times while the cover member 13 is replaced every 60 times. This was done for 20 process tubes.

As a result of Example 1, no crack occurred in any of the process tubes.
Further, in the investigation of the SixOy film in the gas exhaust region, in any process tube, the SixOy film is directly formed on the inner surface of the gas exhaust pipe or the inner wall surface of the process tube main body around the connection portion of the gas exhaust pipe. In particular, no thick spots were observed, and no peeling was observed.

(Comparative Example 1)
The heat treatment is performed in the same manner as in Example 1 except that a conventional heat treatment furnace without a cover member as shown in FIG. 5 is used and that the cover member is not replaced.
As a result of performing this process on 18 process tubes, cracks were generated in 2 process tubes. One crack was generated on the inner surface of the gas exhaust pipe, and the other was the inner wall surface of the process tube main body near the gas exhaust pipe.

(Comparative Example 2)
A cylindrical cover member (height 34 cm) was provided, and this was inserted into the process tube body to cover the area other than the soaking zone. Thus, heat treatment was performed in the same manner as in Example 1 except that a heat treatment furnace covering only the inner wall surface of the lower part of the process tube main body was used, and 10 process tubes were evaluated.
As a result, cracks occurred on the inner surface of the gas exhaust pipe of one of the 10 process tubes.

(Comparative Example 3)
Heat treatment is performed in the same manner as in Example 1 except that a cylindrical cover member (length: 6.0 cm) is provided, which is inserted into the gas exhaust pipe, and a heat treatment furnace that covers only the inner surface of the gas exhaust pipe is used. And 7 process tubes were evaluated.
As a result, in one of the seven process tubes, a crack occurred on the inner wall surface of the process tube main body near the gas exhaust pipe.

  As described above, the process tube main body around the connection portion of the gas exhaust pipe, which is a gas exhaust region to which SixOy easily adheres, as long as it has the removable cover member 13 like the heat treatment furnace 1 of the present invention. Both the inner wall surface and the inner side surface of the gas exhaust pipe near the process tube main body can be covered, and even if the number of heat treatments is increased, it is possible to effectively prevent SixOy from directly adhering to the gas exhaust region. Then, the SixOy film deposited by replacing the cover member 13 can be removed out of the system. As a result, cracks do not occur in the gas exhaust region of the quartz process tube where cracks are likely to occur, and the life of the heat treatment furnace can be extended. Therefore, significant improvement in productivity and cost can be achieved.

On the other hand, Comparative Example 1 that does not include a cover member, Comparative Example 2 that includes a cover member, but covers only the inner wall surface of the process tube body around the connection portion of the gas exhaust pipe, and Comparative Example that covers only the inner surface of the gas exhaust pipe In No. 3, when the number of heat treatments was increased, the SixOy film adhered and peeled, and cracks occurred in the portions not covered with the cover member in the gas exhaust region.
Accordingly, it is important to simultaneously cover both the inner wall surface of the process tube body around the connection portion of the gas exhaust pipe and the inner surface of the gas exhaust pipe near the process tube body as in the heat treatment furnace 1 of the present invention. I understand that.

  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.

It is the schematic which shows an example of the heat processing furnace of this invention. It is the schematic which shows an example of the cover member comprised in the heat processing furnace of this invention. It is explanatory drawing which shows a mode that the cover member is inserted by the gas exhaust pipe. It is explanatory drawing which shows a mode that SixOy has accumulated on the cover member in the heat processing furnace of this invention. It is the schematic which shows an example of the conventional vertical heat processing furnace. It is explanatory drawing which shows a mode that the crack has generate | occur | produced in the gas exhaust_gas | exhaustion area | region in the conventional heat processing furnace.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Heat processing furnace in this invention, 2 ... Heater, 3 ... SiC soaking tube,
4 ... Process tube made of quartz, 5 ... Boat, 6 ... Insulation tube, 7 ... Furnace port,
8 ... Lid, 9 ... Soaking, 10 ... Process tube body,
10f ... Inner wall surface of the process tube body around the connection part of the gas exhaust pipe,
11 ... Gas introduction pipe, 12 ... Gas exhaust pipe, 12di ... Inner diameter of gas exhaust pipe,
12f ... the inner surface of the gas exhaust pipe,
13 ... cover member, 14 ... cylinder part, 14do ... outer diameter of cylinder part,
14l ... length of the cylinder part, 15 ... flange part, 15do ... outer diameter of the flange part,
W: Semiconductor substrate.

Claims (3)

At least a heat treatment furnace having a quartz process tube for heat treating a semiconductor substrate in an atmosphere of Ar, hydrogen, or a mixed gas thereof,
The quartz process tube was introduced into the process tube main body into which the semiconductor substrate to be heat-treated was inserted, and a gas introduction tube for introducing the Ar, hydrogen, or a mixed gas thereof into the process tube main body. A gas exhaust pipe for exhausting gas from the process tube body;
The heat treatment furnace further comprises a removable cover member that is inserted into the gas exhaust pipe from the inside of the process tube main body,
The cover member has an outer diameter smaller than the inner diameter of the gas exhaust pipe, a cylindrical portion inserted into the gas exhaust pipe, and a flange portion having an outer diameter extending to one end of the cylindrical portion larger than the inner diameter of the gas exhaust pipe; A heat treatment furnace characterized by comprising:   The heat treatment furnace according to claim 1, wherein the cover member is made of quartz having a lower viscosity than the quartz of the quartz process tube.   The heat treatment furnace according to claim 1, wherein the cover member is an oxyhydrogen flame molten product or a synthetic quartz product.

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