JP2001156076A - Method for manufacturing silicon semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a semiconductor substrate for preparation of a semiconductor device, which can effectively reduce or eliminate a device preparation problem of crystal defect, which could not be removed completely in the prior art with a good productivity, and which can provide a very good electrical characteristic to the device highly sensitive to the defect even at the time of measuring the characteristic. SOLUTION: In the method for manufacturing a semiconductor device, a silicon semiconductor substrate obtained from a silicon single crystal grown by a Czochralski method, or magnetic-field application Czochralski method using a silicon melt containing nitrogen atoms corresponding to not less than 1×1016 atoms/cm3 and not larger than 3×1019 atoms/cm3 is heat treated in an atmosphere containing 5 ppm or less of rate impurity gas, at a temperature in a range not lower than 1000 deg.C and not higher than 1300 deg.C for one or more hours. As a result, by the method, there can be provided a substrate which has a surface defective layer having in a substantially non-defect, excellent electrical characteristic, and a wafer which has a high device production yield.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a silicon semiconductor substrate, and more particularly to a method for removing a defect inside a substrate or a surface of a substrate and generating no new defects during device fabrication. The present invention relates to a method for manufacturing a silicon semiconductor substrate that can be improved.

[0002]

2. Description of the Related Art COPs harmful to the production of such devices
Crystal growth as one of the technologies to reduce or eliminate
There is a known technology for heat treatment of crystals to which nitrogen is sometimes added.
You. Japanese Patent Application Laid-Open No. 10-98047 discloses that
Also 1x10¹⁴atoms / cm ^ThreeDoping
Reduce the size of vacancy defects, and remove vacancies by heat treatment.
Techniques have been disclosed to make the pits more easily disappear. Only
Meanwhile, the oxygen concentration usually used industrially (7 to
10x10¹⁷atoms / cm^Three, JEIDA conversion)
1x10 nitrogen in the crystal¹⁴atoms / cm^ThreeDopi
Nucleation of many oxygen precipitates and stacking faults in the crystal
Are formed, and after heat treatment, these defects appear on the surface and appear.
The problem is that the defect density of the surface
You. For this reason, an embodiment disclosed in JP-A-10-98047 is disclosed.
4.5x10 at which no oxygen precipitates¹⁷atoms
/ Cm^ThreeA crystal having an oxygen concentration of In fact this
The effect of defect formation by adding nitrogen is described in Japanese Patent Application Laid-Open No. 11-189.
No. 493, entitled "Promotion of substrate deposition of epitaxial layer"
It is used as a means for progress.

In addition, as Japanese Patent Application No. Hei 11-84915, we have proposed a method in which 1 × 10 ¹⁶ atoms / cm ³ or more and 1.5 × 1
A silicon semiconductor substrate obtained from a silicon single crystal grown by a Czochralski method or a Czochralski method with the application of a magnetic field using a silicon melt containing nitrogen of 0 ¹⁹ atoms / cm ³ or less is cooled to 1000 ° C. to 1300 ° C. A method of performing heat treatment at a temperature for 1 hour or more is proposed. According to this method, defects on the substrate surface can be eliminated irrespective of the effect of promoting the generation of defects by nitrogen of the substrate, but sometimes the precipitates become minute defects that cannot be detected by a normal defect detection method, It may remain near the substrate surface and degrade the electrical characteristics.

A method of doping nitrogen during single crystal growth of silicon is disclosed in Japanese Patent Application Laid-Open No. 60-25119.
No. 0 publication is known. In addition, the float zone (F
Z) The effect of adding nitrogen in a single crystal is disclosed in
For example, Japanese Patent No. 17497 discloses an increase in crystal strength.
No. 91993 discloses a method for suppressing a change in resistivity.

[0005]

SUMMARY OF THE INVENTION The present invention is to provide a silicon semiconductor substrate for producing a semiconductor device, with good productivity, a crystal defect which becomes a problem in device production which cannot be completely removed by the conventional technique as described above. It is an object of the present invention to provide a method for manufacturing a semiconductor substrate which can be effectively reduced or eliminated and which can obtain very good characteristics even in measurement of electrical characteristics of a device which is extremely sensitive to defects.

[0006]

Means for Solving the Problems We have conducted intensive studies on defects generated in a silicon semiconductor substrate, and have been able to almost completely eliminate defects having a problematic size in a device fabrication region of a silicon semiconductor substrate, and The inventors have found that the electrical characteristics of the device can be greatly improved by completely eliminating even minute defects that cannot be detected by a normal defect detection method, and have completed the invention.

That is, the present invention provides 1 × 10 ¹⁶ atoms /
A silicon semiconductor substrate obtained from a silicon single crystal grown by a Czochralski method or a Czochralski method applying a magnetic field using a silicon melt containing nitrogen of not less than 3 cm ^{3 and not} more than 3 × 10 ¹⁹ atoms / cm ³ contains impurities. The amount is 5p
1000 ° C. to 130 in a rare gas atmosphere of not more than pm
A method for manufacturing a silicon semiconductor substrate, comprising performing heat treatment for 1 hour or more in a temperature range of 0 ° C. or less. In particular, the present invention relates to a method for manufacturing a silicon semiconductor substrate in which the rare gas is an argon gas. Further, in the manufacturing method, in order to prevent the purity of the atmosphere from deteriorating during the heat treatment, a purge box is provided in the furnace port of the heat treatment furnace, and a purge is performed with a rare gas at the time of insertion to reduce the impurity concentration in the atmosphere of the furnace port to 5 ppm. A method for manufacturing a silicon semiconductor substrate characterized by the following.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

Normally, a silicon substrate used for producing an integrated circuit is grown by the Czochralski method or the Czochralski method applying a magnetic field. On this occasion,
1 × 10 ¹⁶ atoms / cm ³ or more and 3 × 10 ¹⁹ atoms
By using a silicon melt containing nitrogen of s / cm ³ or less, 1 × 10 ¹³ atoms / cm ³ or more and 1 × 1
Crystals containing nitrogen of 0 ¹⁶ atoms / cm ³ or less can be grown. As a method for adding nitrogen to the melt, Japanese Patent Application Laid-Open
As disclosed in Japanese Patent Application No. 0-251190, silicon nitride can be introduced by melting the raw material together with the raw material, or by blowing nitrogen gas to the raw material polycrystalline silicon which has become hot. However, since the method using gas depends on the quantitative property, it is preferable to melt high-purity silicon nitride together with the raw material. The segregation coefficient of nitrogen is 7 × 10 ^-4 and 1 × 10 ¹⁶ a
If a silicon melt containing nitrogen of not less than toms / cm ^{3 and not} more than 3 × 10 ¹⁹ atoms / cm ³ is used, 1 × 10 ¹³
It is possible to grow a crystal containing nitrogen of atoms / cm ³ or more and 1 × 10 ¹⁶ atoms / cm ³ or less. Since most of the defects generated during crystal growth of crystals containing nitrogen are oxygen precipitates, defects can be almost completely eliminated only by outward diffusion of oxygen on the wafer surface. it can. Depending on the pulling conditions, vacancy defects transformed at a density of 5% or less of the oxygen precipitates may be generated. However, these defects have an unstable form and can be easily formed near the surface by heat treatment. Disappear. Utilizing the fact that defects are transformed by the addition of nitrogen, we filed this patent into a wafer with few defects near the surface by subjecting this crystal to a wafer and then performing a heat treatment in a non-oxidizing atmosphere. No. 11-84915. In the present invention, the heat treatment temperature is 1000 ° C. or more and 1300 ° C.
In the following, it is pointed out that the temperature is desirably 1100 ° C. or more and 1200 ° C. or less, and that surface defects can be eliminated by heat treatment at a lower temperature than conventional crystals. In addition, as a guideline for determining the heat treatment temperature, if the temperature is low, a large amount of time is required for out-diffusion of oxygen, and if the temperature is too high, the thermal equilibrium solid solubility in the crystal increases and the outward diffusion of oxygen does not occur. In addition, at 1150 ° C. or higher, the higher the temperature, the more likely the problem of surface roughness of the substrate surface occurs. Furthermore, when the processing furnace is operated at a high temperature, unexpected contamination of the furnace body is likely to occur. Considering 115
It is pointed out that it is desirable to determine the temperature around 0 ° C.

In the present invention, there is basically no change in consideration of the heat treatment conditions. However, in order to obtain a more complete and defect-free surface-free layer which is the object of the present invention, the above heat treatment conditions must be further optimized. First, the atmosphere must be a non-oxidizing atmosphere, particularly a rare gas atmosphere, preferably an argon atmosphere. The non-oxidizing atmosphere includes an atmosphere having an active reducing action such as hydrogen and an inert gas atmosphere which is not a rare gas such as nitrogen. In an atmosphere having an active reducing action, such as hydrogen, it reacts with atoms added to make electric resistance of phosphorus, boron, etc. on the outermost surface of the wafer to a predetermined value, and sublimates those atoms. . Therefore, the electric resistance changes within a range of several μm near the wafer surface. In addition, a reducing atmosphere such as hydrogen has a disadvantage that it is not easy to handle because of the danger of explosion. On the other hand, nitrogen reacts with silicon to form a nitride and hinders outward diffusion of oxygen necessary for annihilation of defects, so that a residual defect occurs in the defect-free layer on the surface. From this, in order to obtain a defect-free layer on the surface more completely, it is necessary to use a rare gas atmosphere which does not react with silicon and does not prevent outward diffusion of oxygen on the surface. As a rare gas, helium and argon, which are relatively inexpensive, are desirable. However, argon is practically easy to handle because helium has excellent heat conduction and poor heat retention.

Further, in order to make the out-diffusion of oxygen on the crystal surface by the heat treatment in the rare gas and the elimination of defects due to the out-diffusion complete, the impurity concentration in the rare gas, particularly the concentration of oxygen or moisture, is increased. Must be kept below 5 ppm. If the impurity concentration is higher than that, the oxygen concentration on the outermost surface of the wafer, particularly the oxygen concentration on the outermost surface of the wafer at a relatively low temperature in the early stage of the heat treatment is not sufficiently reduced, and the defect disappearance is hindered. Also,
It goes without saying that no matter how much the impurity concentration of the gas itself is reduced, there is no effect if impurities are mixed before the wafer actually comes into contact with the wafer. It is preferable to provide a purge box at the furnace port so as not to enter.

The use of a rare gas, preferably an argon atmosphere as described above, and sufficient care to prevent impurities from entering the atmosphere during the heat treatment until the gas actually comes into contact with the wafer, eliminates oxygen during the heat treatment. In this case, the oxygen concentration on the wafer surface at the early stage of the heat treatment is sufficiently reduced, and a more complete surface defect-free layer can be obtained. In particular, in the case of nitrogen-added crystals, the defects themselves generated during crystal growth are more easily eliminated than the defects generated in ordinary crystals, but the density is extremely large, so that the effect of oxygen diffusion by the atmosphere control can be reduced. If it is not enough, small defects that cannot be detected by a normal defect detection method remain in the defect-free layer on the surface, and the merit of adding nitrogen is lost.

[0013]

The present invention will be specifically described below with reference to examples.

Example 1 A silicon crystal was pulled up by the Czochralski method.
Dissolve about 40kg of raw material, about 30k of 155mm diameter
g of ingots were made. The specific resistance of the crystal is p-type 10
Ωcm. Nitrogen is added so that a wafer having a nitride film formed on a non-doped silicon crystal by a CVD method is melted at the same time as the raw material is melted, so that the nitrogen concentration in the melt of the raw material becomes 5 × 10 ¹⁸ atoms / cm ^3. I made it. After growing the crystal, the oxygen concentration of the crystal was measured to be about 8 × 1
0 ¹⁷ atoms / cm ³ (JEIDA by infrared absorption method
Measured using the conversion coefficient of
Was about 5 × 10 ¹⁵ atoms / cm ³ .

After processing the crystal into a wafer having a diameter of 150 mm (6 inches), the crystal was subjected to the following heat treatment. That is, 800
The silicon substrate was inserted into the furnace at a temperature of 10 ° C., the temperature was increased at a rate of 10 ° C./min after the insertion, the temperature was maintained at 1150 ° C. for 4 hours, the temperature was lowered at a rate of −10 ° C./min, and the substrate was taken out at a temperature of 800 ° C. As a gas used for the heat treatment, an argon gas supplied by a cold evaporator was generated at a use point by a purifier and used. The impurity concentration in the gas was 1 ppm or less. This gas was used as an atmosphere throughout the heat treatment. In addition, when inserting the substrate, purging was performed by a purge box provided in front of the furnace, and after confirming that the atmosphere in front of the furnace in which the sample was on standby was an argon atmosphere of 1 ppm or less of impurities, the furnace port was opened. The substrate was inserted.

In order to examine the surface defects of this wafer, an infrared tomograph (M
O-6). As a result, the number of defects on the entire surface of the wafer was about 200 / wafer.

The electrical characteristics of the surface defect-free layer of this wafer were examined by two methods.

The first measuring method is TZDB (time
zero dielectricbreak dow
n) is the oxide film breakdown voltage. 100 on the substrate surface after heat treatment
An oxide film having a thickness of 25 nm was formed in a dry oxygen atmosphere at 0 ° C., and the breakdown voltage of the oxide film was measured. The electrode used for withstand voltage measurement is 20 mm
² is a polysilicon electrode, and the determination current is 100 mA. Those showing a withstand voltage of 11 MV or more indicating the ratio of non-defective products were 99% of the whole.

Further, in order to examine the electrical characteristics of the defect-free layer in a deep place, the surface of the wafer which had been subjected to the above-mentioned argon heat treatment was shaved by 3 μm by mirror polishing, and the same measurement was performed. As a result, those showing a withstand voltage of 11 MV or more are:
It was 95% of the whole.

The second measuring method is TDDB (time
dependent dielectric break
k down). Heat as above
The substrate surface after the treatment is placed in a dry oxygen atmosphere at 1000 ° C.
An oxide film of 3 nm is formed, and the electrode area is 10 mm^Two, Current tight
5mA / cm^Two, Measurement was performed at a judgment voltage of 10 MV / cm.
Was. Breakdown charge 10C / cm^TwoCumulative failure rate is about 3
%Met. In addition, investigate characteristics at a deep position from the surface
In order to perform the above-mentioned argon heat treatment,
3 μm was scraped off by mirror polishing, and the same measurement was performed. Destruction
Charge 10C / cm ^TwoCumulative failure rate is about 9%.
Was.

Example 2 A wafer obtained from the same crystal as in Example 1 was subjected to the following heat treatment. That is, a silicon substrate was inserted into a furnace at 800 ° C., the temperature was raised at 10 ° C./min after insertion, the temperature was maintained at 1150 ° C. for 4 hours, the temperature was lowered at −10 ° C./min, and the substrate was taken out at 800 ° C. . As a gas used for the heat treatment, an argon gas supplied by a cold evaporator was generated at a use point by a purifier and used. The impurity concentration in the gas was 1 ppm or less. This gas was used as an atmosphere throughout the heat treatment. However, unlike Example 1, the purging by the purge box at the furnace port was not performed.

The same evaluation as in Example 1 was performed for the crystal evaluation and the electrical characteristics of the surface defect-free layer of this wafer. Table 1 shows the results. Although it is slightly inferior to Example 1, it shows good electrical characteristics.

Example 3 A silicon crystal was pulled up by the Czochralski method.
Dissolve about 40kg of raw material, about 30k of 155mm diameter
g of ingots were made. The specific resistance of the crystal is p-type 10
Ωcm. Nitrogen is added so that a wafer in which a nitride film is formed on a non-doped silicon crystal by a CVD method is melted at the same time as the raw material is melted, so that the nitrogen concentration in the melt of the raw material becomes 2 × 10 ¹⁶ atoms / cm ^3. I made it. After growing the crystal, the oxygen concentration of the crystal was measured to be about 8 × 1
0 ¹⁷ atoms / cm ³ (JEIDA by infrared absorption method
(Measured using a conversion coefficient of Nitrogen concentration is SI
Although it could not be measured by MS, it was estimated to be about 2 × 10 ¹³ atoms / cm ³ when estimated from the ratio of the nitrogen concentration in the melt to the nitrogen concentration in the crystal in Example 1.

After processing this crystal into a wafer having a diameter of 150 mm (6 inches), the crystal was subjected to the following heat treatment. That is, 800
The silicon substrate was inserted into the furnace at a temperature of 10 ° C., the temperature was raised at a rate of 10 ° C./min after the insertion, the temperature was maintained at 1200 ° C. for 2 hours, the temperature was lowered at a rate of −10 ° C./min, and the substrate was taken out at a temperature of 800 ° C. As a gas used for the heat treatment, an argon gas supplied by a cold evaporator was generated at a use point by a purifier and used. The impurity concentration in the gas was 1 ppm or less. This gas was used as an atmosphere throughout the heat treatment. In addition, when inserting the substrate, purging was performed by a purge box provided in front of the furnace, and after confirming that the atmosphere in front of the furnace in which the sample was on standby was an argon atmosphere of 1 ppm or less of impurities, the furnace port was opened. The substrate was inserted.

The same evaluation as in Example 1 was performed for the evaluation of the crystal and the evaluation of the electrical characteristics of the wafer. Table 1 shows the results. It can be seen that good electrical characteristics were obtained as in Example 1.

Example 4 A silicon crystal was pulled up by the Czochralski method.
Dissolve about 40kg of raw material, about 30k of 155mm diameter
g of ingots were made. The specific resistance of the crystal is p-type 10
Ωcm. Nitrogen is added so that a wafer having a nitride film formed on a non-doped silicon crystal by a CVD method is melted at the same time as the raw material is melted, so that the nitrogen concentration in the melt of the raw material becomes 3 × 10 ¹⁹ atoms / cm ^3. I made it. During crystal growth, the ingot was poly-crystallized in the latter half, but dislocation-free crystals were obtained from above the ingot. The oxygen concentration of the crystal was measured to be about 8 × 10 ¹⁷ atoms / cm ³ (measured by the infrared absorption method using the conversion coefficient of JEIDA), and the nitrogen concentration was measured to be about 3 × 10 ¹⁶ by SIMS.
atoms / cm ³ .

After processing the crystal into a wafer having a diameter of 150 mm (6 inches), the following heat treatment was performed. That is, 800
The silicon substrate was inserted into the furnace at a temperature of 10 ° C., the temperature was raised at a rate of 10 ° C./min after the insertion, the temperature was maintained at 1200 ° C. for 2 hours, the temperature was lowered at a rate of −10 ° C./min, and the substrate was taken out at a temperature of 800 ° C. As a gas used for the heat treatment, an argon gas supplied by a cold evaporator was generated at a use point by a purifier and used. The impurity concentration in the gas was 1 ppm or less. This gas was used as an atmosphere throughout the heat treatment. In addition, when inserting the substrate, purging was performed by a purge box provided in front of the furnace, and after confirming that the atmosphere in front of the furnace in which the sample was on standby was an argon atmosphere of 1 ppm or less of impurities, the furnace port was opened. The substrate was inserted.

The same evaluation as in Example 1 was performed for the crystal evaluation and the electrical characteristic evaluation of the wafer. Table 1 shows the results. It can be seen that good electrical characteristics were obtained as in Example 1.

[0029]

[Table 1]

Comparative Example 1 A silicon crystal was pulled up by the Czochralski method.
Dissolve about 40kg of raw material, about 30k of 155mm diameter
g of ingots were made. The specific resistance of the crystal is p-type 10
Ωcm. Nitrogen is added so that a wafer having a nitride film formed on a non-doped silicon crystal by a CVD method is melted at the same time as the raw material is melted, so that the nitrogen concentration in the melt of the raw material becomes 5 × 10 ¹⁵ atoms / cm ^3. I made it. After growing the crystal, the oxygen concentration of the crystal was measured to be about 8 × 1
0 ¹⁷ atoms / cm ³ (JEIDA by infrared absorption method
(Measured using a conversion coefficient of Nitrogen concentration is SIM
Although it could not be measured by S, it was estimated to be about 5 × 10 ¹² atoms / cm ³ when estimated from the ratio of the nitrogen concentration in the melt to the nitrogen concentration in the crystal in Example 1.

After processing the crystal into a wafer having a diameter of 150 mm (6 inches), the following heat treatment was performed. That is, 800
The silicon substrate was inserted into the furnace at a temperature of 10 ° C., the temperature was raised at a rate of 10 ° C./min after the insertion, the temperature was maintained at 1200 ° C. for 2 hours, the temperature was lowered at a rate of −10 ° C./min, and the substrate was taken out at a temperature of 800 ° C. As a gas used for the heat treatment, an argon gas supplied by a cold evaporator was generated at a use point by a purifier and used. The impurity concentration in the gas was 1 ppm or less. This gas was used as an atmosphere throughout the heat treatment. In addition, when inserting the substrate, purging was performed by a purge box provided in front of the furnace, and after confirming that the atmosphere in front of the furnace in which the sample was on standby was an argon atmosphere of 1 ppm or less of impurities, the furnace port was opened. The substrate was inserted.

The same evaluation as in Example 1 was performed for the evaluation of the crystal and the evaluation of the electrical characteristics of the wafer. Table 2 shows the results. It can be seen that all the characteristics are deteriorated as compared with Example 1.

Comparative Example 2 A crystal similar to that of Comparative Example 1 was formed without adding nitrogen, and the same heat treatment was performed after wafer processing. Crystal evaluation and electrical characteristic evaluation of this wafer were performed in the same manner as in Example 1. Table 2 shows the results. It can be seen that the electrical characteristics are worse than in Example 1.

Comparative Example 3 Using the crystal of Comparative Example 2 grown without adding nitrogen,
The following heat treatment was performed. That is, the silicon substrate is inserted into the furnace at 800 ° C., and after the insertion, the temperature is increased at 10 ° C./min.
C. for 2 hours, and then the temperature was lowered at -10.degree.
The substrate was taken out at ℃. As a gas used for the heat treatment, an argon gas supplied from an Ar cylinder was used without being purified.
The impurity concentration in the gas was 50 ppm. This gas was used as an atmosphere throughout the heat treatment.

The wafer was evaluated for crystal and electric characteristics in the same manner as in Example 1. Table 2 shows the results. It can be seen that the electrical characteristics are worse than in Example 1.

Comparative Example 4 A wafer prepared from the crystal used in Example 1 was used in Comparative Example 3
The same heat treatment as above was performed.

The wafer was evaluated for crystal and electric characteristics in the same manner as in Example 1. Table 2 shows the results. It can be seen that the electrical characteristics are much worse than in Example 1.
It should be noted here that the influence of the heat treatment atmosphere is not so large in the case of the crystal to which nitrogen is not added (comparison between Comparative Example 2 and Comparative Example 3), but is very large in the case of the crystal to which nitrogen is added. (Comparison between Example 1 and Comparative Example 4). From this, it is understood that in the case of the nitrogen-added crystal, it is particularly important to purify and control the heat treatment atmosphere.

[0038]

[Table 2]

[0039]

As described above, according to the present invention, a wafer having excellent electrical characteristics can be obtained by annealing a nitrogen-added crystal in a high-purity rare gas atmosphere. Further, according to the present invention, it is possible to combine a defect-free surface and a high gettering ability inside a bulk, which are features when an nitrogen-doped crystal is annealed, and to provide a wafer excellent in device fabrication. Can be created.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/322 H01L 21/322 Y (72) Inventor Yasumitsu Ota 20-1 Shintomi, Futtsu-shi, Chiba New Japan Inside the Technology Development Division, Steel Corporation (72) Inventor Wataru Ohashi 20-1 Shintomi, Futtsu-shi, Chiba Prefecture Inside the Technology Development Division, Nippon Steel Corporation (72) Hiroyuki Deai 20-1 Shintomi, Futtsu-shi, Chiba New Japan (72) Inventor Hideki Yokota 20-1 Shintomi, Futtsu-shi, Chiba F-term (reference) 4G077 BA04 CF10 EC10 FE02 FE11 FK11 HA12

Claims (3)

[Claims] 1. 1 × 10 ¹⁶ atoms / cm ³ or more and 3 ×
A silicon semiconductor substrate obtained from a silicon single crystal grown by a Czochralski method or a Czochralski method with the application of a magnetic field using a silicon melt containing nitrogen of 10 ¹⁹ atoms / cm ³ or less has an impurity content of 5 ppm or less. A method for manufacturing a silicon semiconductor substrate, comprising performing heat treatment in a rare gas atmosphere at a temperature in the range of 1000 ° C. to 1300 ° C. for 1 hour or more. 2. The method according to claim 1, wherein the rare gas is an argon gas. 3. The manufacturing method according to claim 1, wherein the heat treatment is performed to prevent the purity of the atmosphere from deteriorating.
A purge box is provided in the furnace port of the heat treatment furnace, and a purge is performed with a rare gas at the time of insertion, and the impurity concentration in the atmosphere of the furnace port is 5 pp.
m or less, the method for manufacturing a silicon semiconductor substrate.