JP2010034307A - Heat processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve processing efficiency of heat processing more with respect to a heat processing method of heat-processing a semiconductor silicon substrate at high temperature in a vertical heat processing furnace. <P>SOLUTION: The heat processing method includes a feeding step of feeding the semiconductor silicon substrate into the vertical heat processing furnace, a heat processing step of raising the in-furnace temperature to perform heat processing in the vertical heat processing furnace, and a taking-out step of lowering the in-furnace temperature and taking the semiconductor silicon substrate out of the vertical heat processing furnace, the in-furnace temperature of the taking-out step being set higher than the in-furnace temperature of the feeding process. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat treatment method in which a semiconductor silicon substrate is placed in a vertical heat treatment furnace, the semiconductor temperature is adjusted by adjusting the temperature in the furnace, and then taken out from the vertical heat treatment furnace.

  A semiconductor silicon substrate (hereinafter, also simply referred to as “substrate”) processed in an LSI device manufacturing process is manufactured by repeating high-temperature heat treatment (annealing) in steps such as oxidation, diffusion, and film formation. In the heat treatment of the substrate, the vertical heat treatment apparatus using a vertical heat treatment furnace (hereinafter also simply referred to as “heat treatment furnace” or “furnace”) can reduce the installation space and can heat a large-diameter substrate in a large amount. Since it is suitable, it is adopted as an apparatus used for various heat treatments of a substrate.

When heat treatment is performed with a vertical heat treatment apparatus, a plurality of semiconductor silicon substrates are placed on a heat treatment jig (also referred to as a heat treatment boat or simply a boat) so as to overlap each other with a space therebetween. A predetermined heat treatment is performed in a heat treatment furnace.
On the other hand, in the case of performing high-temperature heat treatment on a substrate, a heat treatment method has also been proposed in which the inside of a heat treatment furnace is heated in advance so that the time for heating the substrate can be shortened in order to improve production efficiency. .

However, when the temperature at which the boat is charged and taken out from the heat treatment furnace is relatively high, the substrate may be bounced on the boat due to a temperature difference between the inside and outside of the furnace, causing damage to the substrate and / or the boat, There are cases where particles are generated on the substrate. That is, there is a trade-off relationship between the temperature at which the heat treatment furnace is charged and taken out and the number of particles generated.
Therefore, when the furnace is heated in advance, the heating of the furnace temperature at the time of loading and unloading is suppressed to the extent that the number of particles generated does not increase unacceptably when the substrate is loaded or unloaded into the furnace. Technology has been proposed.

  For example, Patent Document 1 focuses on the fact that oxygen precipitation nuclei are not generated in a substrate or may not grow even if the input and extraction temperatures are relatively low. Technology that suppresses the generation of particles caused by hitting the boat and knocking it on the boat due to a rapid temperature change at the time of loading and unloading by keeping the temperature at the inside and the temperature at the inside lower than the heat treatment temperature of the wafer. Proposed. Of course, after the charging, the furnace temperature is raised from the charging temperature to the necessary heat treatment temperature, and after the heat treatment, the furnace temperature is lowered to the take-out temperature.

In addition, in order to further improve the production efficiency when performing high-temperature heat treatment on a substrate, techniques for accelerating cooling inside the heat treatment furnace have also been proposed (Patent Documents 2 to 4).
In Patent Document 2, a plurality of substrates (semiconductor wafers) are mounted on a boat, loaded into a process tube, the process tube is heated to heat-treat the semiconductor wafer, and cooling air is then applied to the outer wall of the process tube. In the process of cooling by feeding in, the blower that feeds cooling air rotates slowly by rotating at low speed at high temperatures, and then rapidly cooling by rotating the blower at high speed, thereby generating slippage on the wafer surface caused by rapid cooling. A heat treatment method for preventing it has been proposed.

  In Patent Document 3, the reaction vessel is made into a single tube to reduce the heat capacity so that the temperature can be quickly raised and lowered, and the exhaust pipe connecting portion extending above the reaction vessel and the connection to this. Exhaust piping due to radiant heat of the reaction vessel by enabling precise control of the temperature of the exhaust piping to be able to effectively prevent the generation of particles and bending the exhaust piping connection part It has been proposed to prevent the radiation of heat to the connection part and the exhaust pipe and to facilitate the temperature control thereof.

In Patent Document 4, in the heat treatment apparatus, by reducing the heat capacity of the heat treatment furnace and increasing the temperature raising / lowering speed, the heat treatment time is shortened, and the temperature control of each part constituting the heat treatment apparatus is facilitated. Heat treatment apparatuses that reduce the risk of particle generation have been proposed.
JP 2004-63685 A JP 2002-299269 A JP 2003-209063 A JP 2004-119510 A

  As in the above-mentioned Patent Document 1, the temperature at which the substrate is put into and taken out from the heat treatment furnace is kept lower than the heat treatment temperature of the wafer, and the substrate is placed on the substrate due to a rapid temperature change at the time of loading and unloading. On the substrate by the technology for suppressing the generation of particles and the technology for forcibly lowering the furnace temperature by cooling air while suppressing the generation of particles on the substrate as in the above-mentioned Patent Documents 2 to 4. Although heat treatment at high temperatures can be performed quickly while suppressing the generation of particles, even if these technologies are introduced, the heat treatment at high temperatures still reduces the temperature inside the furnace above a certain level. It takes time.

For this reason, the further improvement of productivity concerning the heat processing of a board | substrate is desired. In particular, it is desired to develop a technique that allows a vertical heat treatment furnace to be used in a time-efficient manner so that more substrates can be heat-treated in a limited facility.
The present invention has been devised in view of such problems, and provides a heat treatment method capable of further improving the treatment efficiency when heat treating a semiconductor silicon substrate at a high temperature in a vertical heat treatment furnace. The purpose is to do.

  In order to achieve the above-mentioned goal, the heat treatment method of the present invention includes a charging step of putting a semiconductor silicon substrate into a vertical heat treatment furnace, a heat treatment step of increasing the furnace temperature and heat-treating in the vertical heat treatment furnace, Thereafter, a heat treatment method comprising an extraction step of lowering the furnace temperature and taking out from the vertical heat treatment furnace, wherein the furnace temperature of the extraction step is set higher than the furnace temperature of the charging step It is characterized by doing.

The furnace temperature in the charging step is room temperature to 400 ° C., and the furnace temperature in the take-out step is preferably 500 to 700 ° C.
When the temperature in the furnace is heated to 500 ° C. or more in advance and the substrate is put into the furnace, the substrate held at room temperature before the loading is first heated from the outer periphery of the substrate, and the outer periphery and the center of the corresponding substrate are heated. A sudden in-plane temperature difference occurs and deforms. Due to the thermal vibration due to this sudden deformation, dust is generated between the substrate and the member supporting the substrate, and the generated dust adheres to another substrate disposed vertically below in the furnace. Although it is a factor that adversely affects the heat treatment and degrades the quality of the substrate, by setting the furnace temperature in the charging process to room temperature to 400 ° C., it is possible to suppress such thermal vibration and prevent degradation of the substrate quality.

  Further, if the furnace temperature in the take-out process is 500 ° C. or higher, the above-described thermal vibration occurs, dust is generated between the substrate and the member supporting the substrate, and the dust is attached to other substrates. The dust generated later does not adversely affect the heat treatment layer itself of the substrate. However, if the furnace temperature in the extraction process is 700 ° C. or higher, the heat released from the opening of the vertical heat treatment furnace at the time of extraction will affect the equipment around the opening (for example, heat damage of rubber packing). Therefore, by setting the furnace temperature in the extraction process to 500 to 700 ° C., the extraction process can be accelerated without causing any trouble.

  The heat treatment of the present invention is performed when heat treatment such as donor killer annealing at 600 ° C. or higher, polysilicon film formation by atmospheric pressure CVD method, hydrogen annealing at 1000 to 1200 ° C., argon annealing, or SIMOX annealing at 1300 ° C. or higher is performed. In particular, in the case of heat treatment that requires a temperature of 1000 ° C. or higher, such as hydrogen annealing, argon annealing, and SIMOX annealing, it takes time to lower the furnace temperature until the heat removal completion process, which increases productivity efficiency. Although the improvement has been hindered, by setting the furnace temperature in the take-out process higher than the furnace temperature in the charging process, it is possible to increase the efficiency of these heat treatments and improve the production efficiency.

  Moreover, it is preferable to provide the washing | cleaning process which removes the deposit | attachment on the said semiconductor silicon substrate after the said extraction process. As described above, if the furnace temperature in the take-out process is set higher than the furnace temperature in the input process, dust generation occurs between the board and the member supporting the board due to thermal vibration of the board at the time of take-out. Although the dust generation material adheres to the substrate, the dust generation material does not adversely affect the heat treatment layer itself of the substrate, but the surface of the substrate must be smoothed. In this respect, since the deposit on the semiconductor silicon substrate is removed by the cleaning process, the surface of the substrate is smoothed.

  Furthermore, it is preferable to provide a furnace cooling step for forcibly cooling the inside of the vertical heat treatment furnace after the extraction step. The vertical heat treatment furnace is used for heat treatment of the semiconductor silicon substrate of the next lot after finishing the heat treatment of one lot of the semiconductor silicon substrate, but it is necessary to lower the temperature of the charging process than the temperature of the extraction process. In this regard, by forcibly cooling the inside of the vertical heat treatment furnace after the extraction process, the start of the heat treatment of the next lot can be accelerated, and the efficiency of the heat treatment can be increased to improve the production efficiency.

  According to the heat treatment method of the present invention, the furnace temperature in the take-out process is set higher than the furnace temperature in the charging process, so it is possible to wait for the furnace temperature to decrease from the temperature in the heat treatment process to the temperature in the charging process. Since the semiconductor silicon substrate is taken out from the vertical heat treatment furnace, it corresponds to the difference between the furnace temperature in the extraction process and the furnace temperature in the input process, from the introduction to the removal of the semiconductor silicon substrate into the vertical heat treatment furnace. , The heat treatment efficiency of the semiconductor silicon substrate can be improved, and the production efficiency can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 8 illustrate a heat treatment method according to an embodiment of the present invention. FIG. 1 is a heat treatment pattern diagram, FIG. 2 is a flow chart of the treatment, and FIG. 3 is a longitudinal sectional view of the vertical heat treatment furnace. FIG. 4 is a perspective view of the heat treatment jig, FIG. 5 is a diagram showing the mounting state of the semiconductor silicon substrate, FIG. 6 is a diagram for explaining the cooling effect, and FIG. FIG. 8 is a heat treatment pattern diagram when this method is applied to a high temperature heat treatment by the SIMOX method.

[Vertical heat treatment equipment]
First, a furnace (vertical heat treatment furnace) of the vertical heat treatment apparatus according to the present embodiment will be described.
As shown in FIG. 3, the vertical heat treatment furnace 3 of the present embodiment includes a tube (process tube, protective tube) 4 that houses a substrate support jig (boat) 2 on which a plurality of semiconductor silicon substrates 1 are placed, A plurality of heaters (heating devices) 5 disposed in a heater chamber 5A around the tube 4, a heater chamber insulating wall insulator 6 provided on the outer periphery (side and upper) of the heater chamber 5A, and a heater chamber 5A And a heat insulating material 7 equipped below.

Further, the vertical heat treatment furnace 3 is provided with a heat buffering jig 8 on a boat elevating robot 9 below the tube 4. The boat 2 is placed on the heat buffering jig 8.
Further, the vertical heat treatment furnace 3 is equipped with an exhaust air duct (rapid cooling duct) 10 communicating with the heater chamber 5A above the tube 4. (Fast cooling fan) 11 is provided. In particular, the exhaust duct 10 is bent to the rear side (horizontal direction) protruding upward (vertically upward) from the upper portion (here, the central upper portion) of the heater chamber 5A and further bent downward (vertically downward). Then, it is bent to the side (horizontal direction) again, and the exhaust fan 11 is mounted on the horizontal portion formed below.

Note that a connecting portion between the heater chamber 5 </ b> A and the exhaust duct 10 may be provided with a shutter 12 that can appropriately block communication between the both 5 </ b> A and 10.
In this way, the exhaust duct 10 is bent from the vertically upward direction to the horizontal direction, so that the radiant heat from the heater 5 heating the tube 4 is formed at the end of the pipe connection portion of the exhaust duct 10 and the like. Since it does not irradiate directly to the flange part etc. which are not shown in figure, temperature control of these members becomes easy. Further, in the present embodiment, the exhaust duct 10 is bent in the horizontal direction from the vertically upward direction, then bent downward in the vertical direction, and bent in the horizontal direction again, so that the distance to the exhaust port in a compact space. The exhaust air temperature discharged from the exhaust air duct 10 can be lowered by passing through the long exhaust air duct 10, and the adverse effect of the high temperature exhaust air can be reduced as much as possible.

[Board support jig (boat)]
A heat treatment jig (boat) 2 for supporting the semiconductor silicon substrate 1 is made of high-purity SiC, Si, or quartz, and as shown in FIG. It is comprised from the upper top plate 22 and the lower top plate 23 which fix the support | pillar part 21 in an up-down position, respectively. A space surrounded by the plurality of support columns 21 is configured as a substrate storage space 24. In addition, an opening 25 is formed by enlarging a part of the space between the plurality of support columns 21 so that the semiconductor silicon substrate can be taken in and out from the side of the substrate storage space 24.

  Grooves are formed at equal intervals in the vertical direction inside each support column 21, and a plurality of substrate support portions 26 projecting toward the substrate storage space 24 are provided between the grooves. From the side, the semiconductor silicon substrate 1 is placed on the substrate support portion 26 of each support column 21 (see FIG. 5), and then placed in the vertical heat treatment furnace 3 to perform a predetermined heat treatment.

[Heat treatment]
The heat treatment according to the present embodiment is performed using the boat 2 and the vertical heat treatment furnace 3 described above. This heat treatment will be described with reference to FIGS.
In the present invention, the furnace temperature (input temperature) when the substrate 1 is input into the vertical heat treatment furnace 3 (input process) is set to room temperature to 400 ° C., but in this embodiment, it is shown in FIG. As described above, the interior of the vertical heat treatment furnace 3 is preheated by operating the heater 5 so that its internal temperature (hereinafter also referred to as furnace temperature) becomes a preset charging temperature (for example, 400 ° C.). (Step S10, preheating step).

  When the charging temperature is 500 ° C. or more, the substrate that has been held at room temperature before the charging is first heated from the outer periphery of the substrate, and a sudden in-plane temperature difference occurs between the outer periphery and the center of the corresponding substrate, causing deformation. Due to the thermal vibration due to this sudden deformation, dust is generated between the substrate and the member supporting the substrate, and the generated dust adheres to another substrate disposed vertically below in the furnace. Although it is a factor that adversely affects the heat treatment and degrades the quality of the substrate, by setting the input temperature to 400 ° C. or less, such thermal vibration can be suppressed and deterioration of the quality of the substrate is prevented.

Then, the substrate 1 is charged into the vertical heat treatment furnace 3 preheated to a predetermined charging temperature (here, 400 ° C.) (step S20, charging process). At this time, the boat raising / lowering robot 9 is lowered, and thereby the boat 2 on which a large number (one lot) of substrates 1 are loaded in advance is placed on the heat buffer jig 8 located at the bottom of the vertical heat treatment furnace 3. .
Thereafter, the boat elevating robot 9 is raised, the boat 2 is placed in the tube 4, and the heater 5 is operated to a higher temperature as shown in FIGS. 1 and 2, and the temperature in the furnace (in the tube 4). Is raised (temperature raised) (step S30, temperature raising step).

When the inside of the furnace (inside the tube 4) reaches a predetermined heat treatment temperature, the heat treatment is performed while maintaining the heat treatment temperature for a predetermined time (step S40, heat treatment step). When the predetermined time has elapsed and the heat treatment is completed, the heater 5 is stopped and the temperature in the furnace (in the tube 4) is lowered (temperature reduction) (step S50, temperature reduction process).
Then, when the furnace temperature reaches the furnace temperature at the time of take-out set to a temperature higher than the input temperature (take-out temperature, set temperature of 500 to 700 ° C.), from inside the vertical heat treatment furnace 3 The boat 2 is taken out (step S60, take-out process).

When the shutter 12 is provided, the shutter 12 is closed during the period from the preheating process to the take-out process.
Then, the surface of the substrate 1 taken out from the vertical heat treatment furnace 3 (the upper surface when placed on the boat 2) is cleaned (step S60, cleaning process).
Further, when the next lot is continuously heat-treated, the inside of the furnace 3 is forcibly cooled to the charging temperature through a determination step (step S80) (step S90, furnace cooling process). If the next lot is not continuously heat-treated, the inside of the furnace 3 is naturally cooled, but in this case as well, the inside of the furnace 3 may be forcibly cooled as in step S90 or slower than this.

When the shutter 12 is provided, the shutter 12 is opened in the furnace cooling process in step S90.
In this in-furnace cooling process, the exhaust fan 11 is operated, the high temperature air in the heater chamber 5A is exhausted through the exhaust duct 10, and cold (about room temperature) outside air enters the heater chamber 5A from an outside air inlet (not shown). By taking in and forcibly cooling the heater chamber 5A, the inside of the furnace (inside the tube 4) is forcibly cooled.

[Action and effect]
Thus, according to this method, since the extraction temperature (in-furnace temperature in the extraction step S60) is set higher than the input temperature (in-furnace temperature in the input step S20), the in-furnace temperature of the heat treatment step S40 is set. Since the substrate 1 is taken out from the vertical heat treatment furnace 3 without waiting for the temperature to fall to the same level as the loading step S20, the vertical heat treatment of the substrate 1 is performed by the difference between the removal temperature and the charging temperature. It is possible to shorten the time from introduction to extraction into the furnace 3, to improve the heat treatment efficiency of the substrate 1, and to improve the production efficiency.

  In particular, in the case of heat treatment that requires a temperature of 1000 ° C. or higher, such as hydrogen annealing, argon annealing, and SIMOX annealing, it takes time to lower the temperature in the furnace until the heat removal completion process, which hinders improvement in productivity efficiency. However, by setting the in-furnace temperature in the take-out process higher than the in-furnace temperature in the charging process, it is possible to increase the efficiency of these heat treatments and improve the production efficiency.

In particular, since the charging temperature is from room temperature to 400 ° C., thermal vibration caused by a rapid temperature change of the substrate can be suppressed, and deterioration of the substrate quality is prevented.
Moreover, although the furnace temperature of the extraction process is set to 500 to 700 ° C., when the furnace temperature of the extraction process is set to 500 ° C. or more, thermal vibration occurs, and the substrate 1 and the member (boat) 2 that supports the substrate 1 During this period, dust is generated and this dust is attached to the lower substrate 1. However, the dust generated after the heat treatment does not adversely affect the heat treatment layer itself of the substrate. In the case of the present embodiment, dust generated after the heat treatment is removed in the cleaning process of step S60, so that the surface of the heat-treated wafer is smoothed and the quality of the heat-treated wafer is ensured.

Further, if the furnace temperature in the extraction process is set to 700 ° C. or higher, the heat released from the opening of the vertical heat treatment furnace at the time of extraction gives a thermal influence on the equipment around the opening (for example, heat damage of rubber packing). However, this is also avoided.
Furthermore, since the furnace cooling step S90 for forcibly cooling the inside of the vertical heat treatment furnace 3 is provided after the take-out process, for example, generally in the temperature range between 500 ° C. and room temperature, the temperature is cooled by the residual heat in the furnace 3. Since the speed is reduced to 1 to 2 ° C./min or less, it takes much time to lower the temperature by natural cooling than about 500 ° C., but it is surrounded by the tube 4 and the heater wall 6 in the furnace 3. The remaining heat in the heater chamber 5A is forcibly exhausted by the exhaust fan 11 installed outside the apparatus, and the furnace 3 is forcibly cooled, so that the temperature cooling rate in the temperature range between 500 ° C. and room temperature is 3 to 3. The temperature can be increased up to 4 ° C./min. As a result, as shown in FIG. 6, for example, when considering cooling at 400 ° C. from 600 ° C. to 200 ° C., the temperature cooling rate when the cooling function is not used is 2 ° C./min, and the temperature when the cooling function is used. When the cooling rate is 4 ° C./min, the time required for temperature reduction can be shortened from 200 minutes to 100 minutes. Therefore, it is possible to efficiently prepare and start the next process within the shortened time.

[Application to specific annealing treatment]
The heat treatment according to the present invention is a heat treatment such as donor killer annealing at 600 ° C. or higher, polysilicon film formation by atmospheric pressure CVD method, hydrogen annealing at 1000 to 1200 ° C., argon annealing, or SIMOX annealing at 1300 ° C. or higher. However, the present invention can be applied as follows.

For example, in the case of applying to the film forming process of polysilicon by the atmospheric pressure CVD method on the 300 mmφ substrate 1, for example, as shown in FIG. The temperature is raised and heat treatment is performed at a furnace temperature of 650 ° C. for a predetermined time.
As shown in FIG. 7B, when the substrate is loaded at a heat treatment temperature of 650 ° C., dust is generated between the substrate and the member supporting the substrate due to thermal vibration, and the other is arranged vertically downward in the furnace. The generated dust adheres to the substrate, and this deposit adversely affects the subsequent heat treatment and degrades the quality of the substrate. If the substrate is charged at 400 ° C. or lower (300 ° C. in this example), The thermal vibration can be suppressed, and the deterioration of the substrate quality can be prevented.

Although it takes a long time to lower the take-out temperature to the input temperature level, in this method, since the take-out temperature is set higher than the input temperature, the substrate after the heat treatment can be taken out relatively quickly.
Further, for example, when applied to a high temperature heat treatment by a SIMOX method for a 300 mmφ substrate, as shown in FIG. 8A, for example, the temperature of the substrate is set to 200 ° C. Heat treatment is performed at a temperature of 1350 ° C. for a predetermined time.

  As shown in FIG. 8B, when the substrate is charged at a heat treatment temperature of 600 ° C., dust is generated between the substrate and the member supporting the substrate due to thermal vibration. The generated dust adheres to the substrate, and this adhered matter adversely affects the subsequent heat treatment and degrades the quality of the substrate. However, if the substrate is charged at 400 ° C. or lower (in this example, 200 ° C.) The thermal vibration can be suppressed, and the deterioration of the substrate quality can be prevented.

  Although it takes a long time to lower the extraction temperature to the input temperature level, in this method, the extraction temperature is set higher than the input temperature, so that the substrate after heat treatment (SIMOX annealing) is taken out relatively quickly. be able to.

[Others]
As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various deformation | transformation is possible in the range which does not deviate from the meaning of this invention.

  Moreover, in this invention, regarding temperature, it is grasped | ascertained by the rough reference | standard of about 50 degreeC unit, and the illustrated input temperature, heat processing temperature, and extraction temperature have illustrated the numerical value from such a viewpoint.

It is the heat processing pattern figure to the semiconductor silicon substrate explaining the heat processing method concerning one Embodiment of this invention. It is a process flowchart explaining the heat processing method concerning one Embodiment of this invention. It is a longitudinal cross-sectional view of the vertical heat processing furnace concerning one Embodiment of this invention. It is a perspective view of the heat treatment jig concerning one embodiment of the present invention. It is a figure which shows the mounting state of the semiconductor silicon substrate to the heat processing jig | tool concerning one Embodiment of this invention. It is a figure explaining the cooling effect in the heat treatment method concerning one embodiment of the present invention. It is the heat processing pattern figure at the time of applying the heat processing method concerning one Embodiment of this invention to the film-forming process of the polysilicon by an atmospheric pressure CVD method, Comprising: (a) is related with this heat processing method, (b) is the comparative example. Indicates. It is the heat processing pattern figure at the time of applying the heat processing method concerning one Embodiment of this invention to the high temperature heat processing by a SIMOX method, (a) is related with this heat processing method, (b) shows the comparative example.

Explanation of symbols

1 Semiconductor silicon substrate (substrate)
2 Substrate support jig (boat)
DESCRIPTION OF SYMBOLS 3 Vertical heat treatment furnace 4 Tube 5 Heater 5A Heater room 6 Heater room heat insulation wall 7 Heat insulation material 8 Thermal buffer jig 9 Boat raising / lowering robot 10 Exhaust duct (rapid cooling duct)
11 Blower (rapid cooling fan)
12 Shutter 21 Supporting part 22 Upper top plate 23 Lower top plate 24 Substrate storage space 25 Opening portion 26 Substrate support portion

Claims (4)

An introduction step of introducing a semiconductor silicon substrate into the vertical heat treatment furnace, a heat treatment step of increasing the furnace temperature and heat-treating in the vertical heat treatment furnace, and then reducing the furnace temperature to reduce the furnace temperature. A heat treatment method comprising an extraction step to take out from the inside,
A heat treatment method, wherein the temperature in the furnace in the removal step is set higher than the temperature in the furnace in the charging step. The furnace temperature in the charging step is room temperature to 400 ° C.,
The heat treatment method according to claim 1, wherein the temperature in the furnace in the extraction step is 500 to 700 ° C. The heat treatment method according to claim 1, further comprising a cleaning step of removing deposits on the semiconductor silicon substrate after the extraction step. The heat treatment method according to any one of claims 1 to 3, further comprising an in-furnace cooling step of forcibly cooling the inside of the vertical heat treatment furnace after the extraction step.

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