JP2010265143A - Method for producing silicon single crystal, and method for producing silicon wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate COP over the whole region in the diameter direction and in the thickness direction of a silicon wafer obtained by slicing a silicon single crystal by subjecting the wafer to oxidative heat treatment. <P>SOLUTION: A silicon melt 15 is stored in a crucible 13 received in a chamber 12. A seed crystal 23 is immersed in the silicon melt 15. A silicon single crystal 11 is pulled up while rotating the seed crystal 23. Then, the silicon single crystal 11 is irradiated with neutrons to dope phosphorus into the silicon single crystal 11. After pulling up the silicon single crystal 11 from the crucible 13, the silicon single crystal 11 having an interstitial oxygen concentration in the inside of 6.0×10<SP>17</SP>atoms/cm<SP>3</SP>or less, and the silicon single crystal 11 containing a COP generating region having a size of 100 nm or less and a density of 3×10<SP>6</SP>atoms/cm<SP>3</SP>, the silicon single crystal 11 is irradiated with neutrons to reduce the variation of an in-plane resistivity in the diameter direction of the silicon single crystal 11 to 5% or less. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing a silicon single crystal by the Czochralski method in order to produce a silicon wafer suitable for an insulated gate bipolar transistor, and a method for producing a silicon wafer with reduced defects inside the wafer. .

  In recent years, development of an insulated gate bipolar transistor (hereinafter referred to as IGBT) has been promoted. An IGBT is not an element that uses only the vicinity of the wafer surface (only in the lateral direction of the wafer) like an LSI such as a memory, but also an element that uses the thickness direction of the wafer (vertical direction of the wafer). Affected by wafer bulk quality. For this reason, it is necessary to reduce not only COP (Crystal Originated Particles) and oxygen precipitates existing in the wafer surface layer but also COP and oxygen precipitates inside the wafer.

Conventionally, a method for manufacturing an IGBT silicon wafer is disclosed in Patent Document 1, for example. In Patent Document 1, a silicon single crystal having an interstitial oxygen concentration of 7.0 × 10 ¹⁷ atoms / cm ³ or less is formed by the Czochralski method (hereinafter referred to as CZ method), and neutrons are formed on the silicon single crystal. The wafer is cut out after doping with phosphorus by irradiating the wire, and the wafer is subjected to annealing in an oxidizing atmosphere at a temperature T (° C.) satisfying the following expression (1) in an atmosphere containing at least oxygen. Forming a polysilicon layer or strained layer on the side is disclosed.

[Oi] ≦ 2.123 × 10 ²¹ exp (−1.035 / k (T + 273)) (1)
In the above formula (1), [Oi] is a measured value by Fourier transform infrared spectrophotometry standardized by ASTM F-121 (1979), and k is a Boltzmann constant of 8.617 × 10 ⁻⁵ eV / K. is there. In a silicon wafer manufactured in this way, COP can be eliminated by annealing a silicon single crystal having an extremely low interstitial oxygen concentration in an oxygen atmosphere. Further, by converting nuclei by irradiating a silicon single crystal with neutrons, a part of silicon atoms is converted into phosphorus atoms, whereby a wafer having a uniform resistivity can be obtained.

Republished patent WO 2004/073057 (Claims 1 and 2, specification page 5, line 9 to page 17, line 17, specification page 5, line 22 to page 26, line 26)

  However, in the method of manufacturing a silicon wafer for IGBT shown in the above-mentioned conventional patent document 1, after a silicon single crystal is pulled up without containing a dopant such as phosphorus in the silicon melt, the silicon single crystal is irradiated with neutrons. As a result, a silicon wafer having a uniform resistivity in the radial direction and the axial direction can be obtained. However, when the size of the COP existing in the silicon single crystal is large or the density of the COP is high, the wafer is oxidized. There was a problem that COP could not be completely eliminated even after heat treatment.

On the other hand, as a silicon single crystal wafer for IGBT, it is required to provide a silicon wafer in which the oxygen concentration is reduced as much as possible and the in-plane resistance distribution is uniform. As a technique for reducing the oxygen concentration in a silicon single crystal, the amount of oxygen taken from the crucible into the silicon melt is reduced by applying a horizontal magnetic field to the silicon melt and slowing the rotation speed of the crucible. It has been known that the interstitial oxygen concentration in the single crystal can be reduced. However, according to experiments conducted by the present inventors, the interstitial oxygen concentration is 6.0 × 10 ¹⁷ atoms / cm ³ only by reducing the rotation speed of the crucible while applying a horizontal magnetic field to the silicon melt. It became clear that a silicon single crystal having a very low oxygen concentration cannot be grown as follows. It was also found that the interstitial oxygen concentration can be further reduced by slowing the rotation speed of the silicon single crystal.

  A first object of the present invention is to provide a silicon single crystal that can extinguish COP over the entire area in the radial direction and thickness direction of the wafer by subjecting a silicon wafer obtained by slicing a silicon single crystal to an oxidation heat treatment. The object is to provide a crystal manufacturing method and a silicon wafer manufacturing method. A second object of the present invention is to provide a method for producing a silicon single crystal that can reduce the interstitial oxygen concentration over substantially the entire length of a plurality of silicon single crystals. A third object of the present invention is to provide a method for producing a silicon single crystal that can reduce the interstitial oxygen concentration in the silicon single crystal by slowing the rotational speed of the silicon single crystal. A fourth object of the present invention is to provide a silicon single crystal capable of relatively widening the pulling speed of the single crystal and reducing variations in in-plane resistivity in the radial direction in the silicon single crystal. It is in providing the manufacturing method of.

According to a first aspect of the present invention, a silicon melt is stored in a crucible housed in a chamber, a seed crystal is immersed in the silicon melt, and the silicon single crystal is pulled up while being rotated. In the method for producing a silicon single crystal in which phosphorus is doped into the silicon single crystal by irradiating neutrons, the silicon single crystal has an internal interstitial oxygen concentration of 6.0 × 10 ¹⁷ atoms / cm ³ or less from the crucible. Then, after pulling up a silicon single crystal including a COP generation region having a size of 100 nm or less and a density of 3 × 10 ⁶ atoms / cm ³ or less, the silicon single crystal is irradiated with neutrons to irradiate the silicon single crystal. A variation of the in-plane resistivity in the radial direction is 5% or less.

  A second aspect of the present invention is an invention based on the first aspect, and further includes a temperature gradient in the pulling axis direction of the silicon single crystal in a temperature range where the central portion of the silicon single crystal being pulled is from the melting point to 1370 ° C. Of these, when the temperature gradient of the central portion of the silicon single crystal being pulled is Gc and the temperature gradient of the outer peripheral portion of the silicon single crystal being pulled is Ge, silicon is used under the conditions satisfying the relationship of Gc / Ge ≧ 1. It is characterized by pulling up a single crystal.

A third aspect of the present invention is an invention based on the first aspect, and further includes silicon single crystals such that the interstitial oxygen concentration in the silicon single crystal is 6.0 × 10 ¹⁷ atoms / cm ³ or less over the entire length. After pulling up the crystal, the silicon raw material is supplied into the crucible and melted, and a new silicon single crystal is pulled from the silicon melt in the crucible to pull up a plurality of silicon single crystals and The silicon single crystal is doped with phosphorus by irradiating each silicon single crystal with neutrons.

  A fourth aspect of the present invention is an invention based on the first to fourth aspects, in which a horizontal magnetic field of 0.2 T or more is further applied to the silicon melt in the crucible and the rotational speed of the crucible is 1. 5 rpm or less, and the rotational speed of the silicon single crystal being pulled is 7 rpm or less.

  According to a fifth aspect of the present invention, there is provided a silicon wafer obtained by slicing a silicon single crystal produced by the method described in the first to fourth aspects, within a range of 1100 to 1300 ° C. in an oxygen gas atmosphere. The silicon wafer manufacturing method is characterized in that the COP is extinguished over the entire area of the silicon wafer by performing a heat treatment of heating to the predetermined temperature and maintaining the predetermined temperature for 2 to 5 hours.

  In the method for producing a silicon single crystal according to the first aspect of the present invention, the silicon single crystal is pulled without containing a dopant such as phosphorus for adjusting the electrical resistivity in the silicon melt, By converting nuclei by neutron irradiation, some silicon atoms are converted to phosphorus atoms and phosphorus is doped into the silicon single crystal, so the concentration of phosphorus in the silicon single crystal is made uniform over the radial and axial directions. can do. As a result, the variation in the in-plane resistivity in the radial direction in the silicon single crystal can be reduced over almost the entire length of the straight body portion of the silicon single crystal. In addition, since a crystal region including a COP generation region having a predetermined size and density is targeted, there is a problem with a defect-free single crystal, that is, the productivity of the defect-free single crystal is reduced, or the allowable pulling speed is wide. The problem that it becomes difficult to control the pulling of the single crystal due to the narrowness can be solved.

  In the method for producing a silicon single crystal according to the second aspect of the present invention, by pulling up the silicon single crystal so that COP is generated under the condition satisfying the relationship of Gc / Ge ≧ 1, A single crystal having a low density can be obtained. When a single crystal is pulled up so that COP is generated under the condition of satisfying the relationship of Gc / Ge <1 of the conventional pulling method, that is, a cooling rate suitable for reducing the COP size by increasing the pulling rate. When the single crystal is pulled in the fast hot zone, the size of the COP in the single crystal decreases, but the density increases. As a result, in the single crystal pulled in the conventional hot zone, COP cannot be extinguished over the entire area in the radial direction and the thickness direction of the wafer by the subsequent oxidation heat treatment, but the single crystal pulled in the hot zone of the present invention. In the crystal, COP can be extinguished over the entire area in the radial direction and the thickness direction of the wafer by the subsequent oxidation heat treatment.

  In the method for producing a silicon single crystal according to the third aspect of the present invention, the silicon raw material is supplied and melted in a crucible immediately after the silicon single crystal is pulled up, and has quality characteristics equivalent to those of the silicon single crystal pulled up earlier. By pulling the silicon single crystal from the crucible, so-called multiple pulling, in which a plurality of silicon single crystals are pulled from one crucible, becomes possible. As a result, the interstitial oxygen concentration can be reduced over substantially the entire length of the straight body portion of the plurality of silicon single crystals.

  In the method for producing a silicon single crystal according to the fourth aspect of the present invention, a horizontal magnetic field is applied to the silicon melt, the rotational speed of the crucible is slowed down, and the rotational speed of the silicon single crystal is slowed down. The silicon single crystal is pulled up in a state where the shape of the solid-liquid interface with the silicon melt is flattened. As a result, even if the rotation speed of the silicon single crystal is decreased, the interstitial oxygen concentration in the silicon single crystal can be reduced over almost the entire length of the straight body portion.

In the silicon wafer manufacturing method according to the fifth aspect of the present invention, the size of the COP in the silicon wafer obtained by slicing the silicon single crystal is 100 nm or less, and the density is 3 × 10 ⁶ atoms / cm ^3. Therefore, if the wafer is subjected to a predetermined oxidation heat treatment, COP can be extinguished over the entire area in the radial direction and thickness direction of the wafer.

It is a longitudinal cross-section block diagram of the apparatus used for the manufacturing method of the silicon single crystal of embodiment of this invention. The left half is a schematic diagram showing the generation behavior of crystal defects generated in a silicon single crystal pulled in a hot zone with a fast cooling rate, and the right half is a silicon single crystal pulled in a hot zone suitable for pulling a defect-free single crystal. It is a schematic diagram which shows the production | generation behavior of the crystal defect which generate | occur | produces in a crystal | crystallization. It is a figure which shows the relationship between the size and density of the light-scattering body (COP) in the wafer of the comparative examples 2 and 3. FIG. It is a figure which shows the relationship between the size and density of the light-scattering body (COP) in the wafer of the comparative example 4 and Example 2. FIG. It is a figure which shows the yield of GOI before and behind performing the oxidation heat processing about the wafer of the comparative examples 2 and 3. FIG. It is a figure which shows the yield of GOI before and behind performing the oxidation heat processing about the wafer of the comparative example 4 and Example 2. FIG. It is a figure which shows the yield of GOI before and behind performing the oxidation heat processing about the wafer of the comparative examples 5 and 6. FIG. It is a figure which shows the yield of GOI before and behind performing the oxidation heat processing about the wafer of Examples 3-5. It is a figure which shows the in-plane distribution of the resistivity before and behind performing neutron irradiation with respect to the silicon single crystal of Example 6 pulled in the hot zone suitable for pulling of a defect-free single crystal. It is a figure which shows the in-plane distribution of the resistivity before and behind performing neutron irradiation with respect to the silicon single crystal of Example 7 pulled in the hot zone suitable for pulling of a defect-free single crystal. It is a figure which shows the relationship between the pulling rate and the interstitial oxygen concentration of two silicon single crystals (Examples 8 and 9) pulled by the multiple pulling method in a hot zone suitable for pulling defect-free single crystals. It is a figure which shows the relationship between the rotational speed of a crucible, the rotational speed of a silicon single crystal, and interstitial oxygen concentration.

  Next, an embodiment for carrying out the present invention will be described with reference to the drawings. As shown in FIG. 1, the pulling device for the silicon single crystal 11 includes a main chamber 12 configured to be vacuumable inside, and a crucible 13 provided in the center of the chamber 12. The main chamber 12 is a cylindrical vacuum container. The crucible 13 includes a bottomed cylindrical inner layer container 13 a formed of quartz and storing the silicon melt 15, and a bottomed cylindrical outer layer container 13 b formed of graphite and fitted to the outside of the inner layer container 13 a. It consists of. The upper end of the shaft 14 is connected to the bottom of the outer layer container 13 b, and a crucible driving means 16 that rotates the crucible 13 through the shaft 14 and moves up and down is provided at the lower end of the shaft 14. Furthermore, the outer peripheral surface of the crucible 13 is surrounded by a cylindrical heater 17 at a predetermined interval from the outer peripheral surface of the crucible 13. Surrounded at intervals.

  On the other hand, a cylindrical pull chamber 19 having a smaller diameter than the main chamber 12 is connected to the upper end of the main chamber 12 so as to communicate with the inside. A pulling rotation means 20 is provided at the upper end of the pull chamber 19. The pulling rotation means 20 is configured to move up and down a pulling shaft 22 having a seed chuck 21 attached to the lower end, and to rotate the pulling shaft 22 about its axis. A seed crystal 23 is detachably attached to the seed chuck 21. After immersing the lower end of the seed crystal 23 in the silicon melt 15, the seed crystal 23 is rotated and pulled up by the pulling and rotating means 20, and the crucible 13 is rotated and raised by the crucible driving means 16. The silicon single crystal 11 is pulled up and pulled up from the lower end of the crystal 23.

  An inert gas such as argon gas is circulated in the main chamber 12. One end of a gas supply pipe 24 is connected to the side wall of the pull chamber 19, and the other end of the gas supply pipe 24 is connected to a tank (not shown) for storing an inert gas. One end of a gas discharge pipe 26 is connected to the lower wall of the main chamber 12, and the other end of the gas discharge pipe 26 is connected to the suction port of the vacuum pump 27. The inert gas in the tank is introduced into the pull chamber 19 through the gas supply pipe 24, passes through the main chamber 12, and is then discharged from the main chamber 12 through the gas discharge pipe 26. . The gas supply pipe 24 and the exhaust pipe 26 are provided with first and second flow rate adjusting valves 41 and 42 for adjusting the flow rate of the inert gas flowing through these pipes, respectively.

  A heat shield 28 is provided in the main chamber 12 to block the irradiation of the radiant heat of the heater 17 to the outer peripheral surface of the silicon single crystal 11 and to rectify the inert gas. The heat shield 28 has a truncated cone-like cylinder that gradually decreases in diameter as it goes downward and surrounds the outer peripheral surface of the silicon single crystal 11 pulled up from the silicon melt 15 at a predetermined interval from the outer peripheral surface. 28a and a flange portion 28b that is connected to the upper edge of the cylindrical body 28a and projects outward in a substantially horizontal direction. In the heat shield 28, the flange portion 28b is placed on the heat retaining cylinder 18 via the ring plate 28c, so that the lower edge of the cylinder 28a is positioned above the surface of the silicon melt 15 with a predetermined gap. In this way, it is fixed in the main chamber 12. Further, the silicon melt 15 is configured to pull up the silicon single crystal 11 while applying a horizontal magnetic field 29. The horizontal magnetic field 29 causes the first and second coils 31 and 32 having the same coil diameter to face each other around the crucible 13 outward from the outer peripheral surface of the crucible 13 at a predetermined interval in the horizontal direction. It is generated by flowing currents in the same direction through these coils 31 and 32, respectively. Note that reference numeral 51 in FIG. 1 denotes a raw material supply pipe for supplying the silicon raw material 52 to the crucible 13. This raw material supply pipe 51 is used in a multiple pulling method for pulling a plurality of silicon single crystals 11 from one crucible 13.

  A method for pulling up the silicon single crystal 11 using the pulling apparatus configured as described above will be described. First, a horizontal magnetic field 29 is generated by applying currents in the same direction to the first and second coils 31 and 32, respectively. The magnetic field strength of the horizontal magnetic field 29 is measured at the intersection of the surface of the silicon melt 15 and the central axis of the crucible 13 so that the magnetic field strength is 0.2 T (Tesla) or more. The current flowing through 32 is controlled. Here, the reason why the magnetic field strength is limited to 0.2 T or more is that if the magnetic field strength is less than 0.2 T, the effect of reducing oxygen uptake into the silicon single crystal 11 is diminished. However, if the magnetic field strength is excessively increased, deterioration of the inner surface of the inner layer container 13a of the crucible 13 may be promoted and dislocation of the single crystal 11 may be caused. Therefore, the magnetic field strength is desirably 0.5 T or less. . Note that a dopant such as P (phosphorus) is not added to the silicon melt 15 in the crucible 13.

Next, of the temperature gradient in the pulling axis direction of the single crystal 11 in the temperature range from the melting point to 1370 ° C. of the central portion of the silicon single crystal 11 pulled using the above apparatus, the temperature gradient of the central portion of the single crystal 11 is expressed as Gc. When the temperature gradient of the outer periphery of the single crystal 11 is Ge, the silicon single crystal 11 is pulled so that COP is generated under the condition satisfying the relationship of Gc / Ge ≧ 1. Here, the reason why the silicon single crystal 11 is pulled up so that COP is generated under a condition satisfying the relationship of Gc / Ge ≧ 1 is to obtain a single crystal 11 having a small COP size and a low density. Specifically, it includes a COP generation region in which the size of the COP in the single crystal 11 is 100 nm or less and the density thereof is 3 × 10 ⁶ atoms / cm ³ or less, preferably 1 × 10 ⁶ atoms / cm ³ or less. The single crystal 11 is pulled up. Here, the size of the COP in the single crystal 11 is limited to 100 nm or less because when the COP size is larger than this size, the COP is difficult to disappear even if a high-temperature oxidation heat treatment is performed. The reason why the density of COP in the crystal 11 is limited to 3 × 10 ⁶ atoms / cm ³ or less is that it exceeds 3 × 10 ⁶ atoms / cm ³ , because the COP density is large. This is because the density increases.

Furthermore, the rotational speed of the crucible 13 during pulling of the silicon single crystal 11 is set to 1.5 rpm or less, preferably 0.3 rpm or less, and the rotational speed of the silicon single crystal 11 being pulled is set to 7 rpm or less, preferably 5 rpm or less. To do. Here, the rotational speed of the crucible 13 is limited to 1.5 rpm or less, and the rotational speed of the silicon single crystal 11 is limited to 7 rpm or less. The interstitial oxygen concentration of the silicon single crystal 11 is 6 × 10 ¹⁷ atoms / cm 3. This is to keep it below ³ . Note that the lower limit of the rotation speed of the silicon single crystal 11 is desirably 0.5 rpm or more, and if it is slower than this, the silicon single crystal 11 is deformed. As described above, by satisfying the condition of Gc / Ge ≧ 1, the shape of the solid-liquid interface between the single crystal 11 and the silicon melt 15 is flattened, and in this state, the horizontal magnetic field 29 is applied to the silicon melt 15. Is applied, the rotational speed of the crucible 13 is decreased, and the rotational speed of the single crystal 11 is further decreased, whereby the interstitial oxygen concentration in the silicon single crystal 11 can be reduced. However, even if the silicon single crystal 11 is pulled up under the above conditions, when the remaining amount of the silicon melt 15 in the crucible 13 decreases, the contact area of the silicon melt 15 with the quartz inner layer container 13a of the crucible 13 becomes the silicon melt. The interstitial oxygen concentration in the silicon single crystal 11 increases relative to the remaining amount of the liquid 15, and the interstitial oxygen concentration is 6 × 10 ¹⁷ atoms / A straight body part exceeding cm ³ will be nurtured.

For this reason, it is effective to pull a plurality of silicon single crystals 11 from one crucible 13 by a multiple pulling method. That is, the silicon single crystal 11 is pulled in a range where the interstitial oxygen concentration in the silicon single crystal 11 does not exceed 6.0 × 10 ¹⁷ atoms / cm ³ , and preferably does not exceed 4 × 10 ¹⁷ atoms / cm ^3. The silicon single crystal 11 is taken out in a state where the inside of the furnace including the inside of the main chamber 12 is kept in vacuum, and the silicon raw material 52 is supplied from the raw material supply pipe 51 to the crucible 13 to be melted. The silicon single crystal 11 is newly pulled from the melt 15. In the pulling by this multiple pulling method, the interstitial oxygen concentration in the silicon single crystal 11 to be pulled is 6.0 × 10 ¹⁷ atoms / cm ³ or less, preferably 4 × 10 ¹⁷ atoms / cm ³ or less. The length from the top to the bottom of the straight body portion of the silicon single crystal 11 to be raised is set in advance. For example, before pulling up the first silicon single crystal 11 or after pulling up one silicon single crystal 11, the silicon raw material 52 is supplied to the crucible 13 and all the melted silicon melt 15 is pulled up as the silicon single crystal 11. When the pulling rate is set to 100%, the pulling of the silicon single crystal 11 is set to be completed when the pulling rate reaches 60 to 80%. Then, after pulling up the silicon single crystal 11 to the preset pulling rate, the silicon raw material 52 is supplied into the crucible 13 from the raw material supply pipe 51 provided in the pulling device and melted, and the seed crystal 23 is melted again with the silicon melt. By newly pulling up the silicon single crystal 11 from the crucible 13 immersed in the liquid 15, a plurality of silicon single crystals 11 are pulled up. As a result, the interstitial oxygen concentration can be reduced over substantially the entire length of the straight body portion of the plurality of silicon single crystals 11. In addition, the interstitial oxygen concentration in the silicon single crystal 11 in this specification is a value measured by Fourier transform infrared spectrophotometry standardized by ASTM F-121 (1979). Here, the interstitial oxygen concentration in the single crystal 11 is limited to 6 × 10 ¹⁷ atoms / cm ³ or less because if it exceeds 6 × 10 ¹⁷ atoms / cm ³ , oxygen precipitates are formed in the single crystal 11. This is because there is a problem that the recombination lifetime is reduced or the resistivity varies due to the formation of oxygen donors, and it becomes difficult to eliminate COP by oxidation heat treatment.

The silicon single crystal 11 thus pulled up is irradiated with neutrons by neutron doping. In the neutron doping method, phosphorus is doped (added) into high-purity silicon single crystal 11 using a reaction that converts ³⁰ Si present in silicon single crystal 11 into ³¹ P by nuclear reaction. In this method, the silicon single crystal 11 is made into a semiconductor. By irradiating the silicon single crystal 11 with neutrons using the above neutron doping method to convert the nuclei, some silicon atoms are converted into phosphorus atoms. As a result, since the silicon single crystal 11 is uniformly doped with phosphorus, the silicon single crystal 11 having a uniform radial in-plane resistivity over the entire length can be obtained. That is, the variation of the in-plane resistivity in the radial direction of the silicon single crystal 11 can be 5% or less, preferably 4% or less. The reason why the variation in the in-plane resistivity in the radial direction of the silicon single crystal 11 is limited to 5% or less is that the quality of the IGBT can be stabilized and the yield in the device process is improved.

  The silicon wafer obtained by slicing the silicon single crystal 11 is heated to a predetermined temperature in the range of 1100 to 1300 ° C., preferably 1150 to 1200 ° C. in an oxygen gas atmosphere. Heat treatment is performed for 5 hours, preferably 3 to 4 ° C. As a result, the COP can be eliminated over the entire area in the radial direction and the thickness direction of the wafer. Here, the heat treatment holding temperature is limited to the range of 1100 to 1300 ° C. The COP is difficult to disappear when the temperature is lower than 1100 ° C., and the thermal load applied to the wafer becomes excessive when the temperature exceeds 1300 ° C. This is because of this. Furthermore, the holding time of the heat treatment is limited to the range of 2 to 5 hours because the COP cannot be sufficiently eliminated in less than 2 hours, and even if the heat treatment is carried out for more than 5 hours, the COP disappearance effect is not so much. Because it doesn't change.

Next, examples of the present invention will be described in detail together with comparative examples.
<Example 1>
Of the temperature gradient in the pulling axis direction of the single crystal 11 in the temperature range from the melting point to 1370 ° C. of the center portion of the silicon single crystal 11 pulled using the pulling apparatus shown in FIG. Is Gc and the temperature gradient of the outer periphery of the single crystal 11 is Ge, the pulling speed is gradually decreased under the condition satisfying the relationship of Gc / Ge = 1.2, that is, in the hot zone B of FIG. The single crystal 11 was pulled up. Here, by applying a horizontal magnetic field of 0.3 T to the silicon melt 15 in the crucible 13, a silicon single crystal having an interstitial oxygen concentration of 13 × 10 ¹⁷ atoms / cm ³ and an interstitial oxygen concentration of 3 × A silicon single crystal of 10 ¹⁷ atoms / cm ³ was pulled. The interstitial oxygen concentration was measured according to the Fourier transform infrared spectrophotometry standardized by ASTM F-121 (1979). Note that no dopant such as phosphorus was added to the silicon melt, and the neutrons were irradiated to the silicon single crystal 11 using a heavy water reactor after the completion of the pulling.

On the other hand, in order to investigate the defect distribution in the single crystal, it is necessary to confirm the generation distribution of the OSF ring. Therefore, in order to confirm the generation distribution of the OSF ring, a silicon single crystal having a high oxygen concentration (oxygen concentration: 13 × 10 ¹⁷ atoms / cm ³ ) was intentionally raised. The results based on the oxygen concentration of low silicon single crystal: to estimate the defect distribution (oxygen concentration ^{3 × 10 17 atoms / cm 3} ). In this case, the other specifications were the same except that the oxygen concentration was different. Specifically, the diameter of the single crystal was 210 mm, the crystal orientation was <100>, and the length of the straight body of the single crystal was 1700 mm. Further, no matter how fast the pulling rate of the single crystal is, the OSF ring generation region cannot be excluded (disappeared) outside the outermost peripheral portion of the single crystal. For this reason, although an OSF ring generation region exists in the outermost peripheral portion of the single crystal, the OSF ring region is formed in the single crystal so that the subsequent single crystal is rounded, that is, the diameter of the single crystal is 210 mm to 200 mm. It is eliminated by cutting the outer peripheral surface of the crystal. For this reason, the diameter of the actual single crystal pulled up was made larger than the target diameter.

<Comparative Example 1>
A hot zone that adjusts the location and structure of the structural components (heat insulation, thermal shield, etc.) in the furnace so that the center of the single crystal to be pulled is accelerated in the temperature range from the melting point to 1370 ° C. That is, except that a silicon single crystal pulling apparatus (not shown) having the hot zone A of FIG. 2 satisfying the relationship of Gc <Ge, specifically, the relationship of Gc / Ge = 0.98 is used. A silicon single crystal was pulled under the same conditions as in Example 1.

<Comparative test 1 and evaluation>
Samples for evaluation were prepared by vertically slicing a single crystal having a high oxygen concentration of 13 × 10 ¹⁷ atoms / cm ³ among silicon single crystals that were pulled up by the apparatus of Example 1 and Comparative Example 1 and irradiated with neutrons. Each was produced. These samples for evaluation were subjected to heat treatment for evaluating oxygen precipitates. Specifically, after the sample for evaluation was held at 800 ° C. for 4 hours in an oxidizing atmosphere, a heat treatment was performed for 16 hours at 1000 ° C. Next, defects were made obvious on the surface of the evaluation sample after the heat treatment by a copper decoration method. Specifically, the evaluation sample surface is contaminated with copper, heat-treated at 1000 ° C. for 1 hour, copper is diffused in the evaluation sample, and then the evaluation sample is rapidly cooled to evaluate the sample. Sample surface defects were revealed. Further, the sample for evaluation after quenching was selectively etched with a light solution, and pits appearing on the surface of the sample for evaluation were observed with an optical microscope. The result is shown in FIG.

  As apparent from FIG. 2, in the hot zone B of the first embodiment, the OSF ring as shown on the right side of FIG. 2 is substantially U-shaped so as to rapidly shrink toward the center when V / G decreases. In the hot zone A of Comparative Example 1, it is confirmed that the OSF ring as shown on the left side of FIG. 2 is substantially V-shaped so that it gradually decreases toward the center as V / G decreases. did it. In addition, the distribution of COP size and density in the COP region is greatly different between the hot zone B of Example 1 and the hot zone A of Comparative Example 1. In the sample for evaluation of the hot zone A of Comparative Example 1, the pulling rate is high. Although the COP size decreases as the speed increases, the COP density increases. On the other hand, in the sample for evaluation in the hot zone B of Example 1, the COP size decreases and the COP density decreases as the pulling speed decreases. It turns out that there is a tendency to decrease.

<Example 2>
In the above comparative test 1, a single crystal (13 × 10 ¹⁷ atoms / cm ³ ) having a high oxygen concentration is vertically divided to reveal defects on the evaluation sample surface. The wafer was cut out from a portion of the silicon single crystal (3 × 10 ¹⁷ atoms / cm ³ ) corresponding to the −2] region having a low oxygen concentration. This wafer was referred to as Example 2. Note that the [B-2] region is a COP generation region close to the OSF ring (a condition where the pulling speed is low).

<Comparative example 2>
[A in the hot zone A on the left side of FIG. 2 obtained by vertically dividing a single crystal (13 × 10 ¹⁷ atoms / cm ³ ) having a high oxygen concentration in the comparative test 1 to reveal defects on the evaluation sample surface. -1] region, a wafer was cut out from a portion of a silicon single crystal (3 × 10 ¹⁷ atoms / cm ³ ) having a low oxygen concentration. This wafer was designated as Comparative Example 2. Note that the [A-1] region means a COP generation region (a condition where the pulling speed is high) far from the OSF ring.

<Comparative Example 3>
[A in the hot zone A on the left side of FIG. 2 obtained by vertically dividing a single crystal (13 × 10 ¹⁷ atoms / cm ³ ) having a high oxygen concentration in the comparative test 1 to reveal defects on the evaluation sample surface. The wafer was cut out from a portion of the silicon single crystal (3 × 10 ¹⁷ atoms / cm ³ ) corresponding to the −2] region having a low oxygen concentration. This wafer was designated as Comparative Example 3. Note that the [A-2] region means a COP generation region close to the OSF ring (a slow pulling speed condition).

<Comparative example 4>
In the above comparative test 1, a single crystal (13 × 10 ¹⁷ atoms / cm ³ ) having a high oxygen concentration is vertically divided to reveal defects on the evaluation sample surface. -1] region, a wafer was cut out from a portion of a silicon single crystal (3 × 10 ¹⁷ atoms / cm ³ ) having a low oxygen concentration. This wafer was designated as Comparative Example 4. Note that the [B-1] region means a COP generation region (a condition where the pulling speed is high) far from the OSF ring.

<Comparative test 2 and evaluation>
The size and density of the COP in the wafers of Example 2 and Comparative Examples 2 to 4 were measured. Specifically, COP size and density distributions were measured for each wafer using an infrared scattering tomograph (Mitsui Metals Co., Ltd .: MO441). The results are shown in FIGS. COP was measured as a light scatterer by infrared scattering tomograph. That is, the density of the light scatterer on the vertical axis in FIGS. 3 and 4 means the density of the COP.

As is apparent from FIG. 3, the wafer of Comparative Example 2 (the wafer in the [A-1] region pulled up under a high pulling speed condition) had a high density even though the COP size was small. Further, the wafer of Comparative Example 3 (the wafer in the [A-2] region pulled under a slow pulling speed condition) had a large COP density but a large size. Furthermore, although the wafer of Comparative Example 2 has a smaller COP size than the wafer of Comparative Example 3, more than half of the wafers have a size exceeding 100 nm. On the other hand, as is apparent from FIG. 4, the wafer of Comparative Example 4 (the wafer in the [B-1] region pulled under a high pulling speed condition) had a small COP density but a large size. On the other hand, in the wafer of Example 2 (wafer in the [B-2] region pulled up under a slow pulling speed condition), there is no COP size smaller than 100 nm, and its density is also 3 × 10. ^{It was 6} atoms / cm ³ or less.

<Comparative test 3 and evaluation>
Using the pulling apparatus of Example 1 and Comparative Example 1, the V / G range when pulling a silicon single crystal was investigated. Specifically, a condition for obtaining the [B-2] region of Example 2, that is, a crystal region having a COP size of 100 nm or less and a density of 3 × 10 ⁶ atoms / cm ³ or less is obtained. The V / G [mm ² / (min · ° C.)] range was investigated. Here, V is the pulling speed (mm / min), and G is the temperature gradient (° C./mm) in the pulling axis direction near the solid-liquid interface. As a result, V / G at which the [B-2] region of Example 2 was obtained was in the range of 0.23 to 0.33 [mm ² / (min · ° C.)]. The range of V / G was obtained by heat transfer calculation using a computer. The area surrounded by the broken line in FIG. 2 has the same COP characteristics as the [B-2] area of Example 2, that is, the COP size is 100 nm or less, and its density is 3 × 10 ⁶ atoms / cm ³ or less. The range of the crystal region is schematically shown. On the other hand, the region surrounded by the two-dot chain line in FIG. 2 has the same COP characteristics as the [B-1] region of Comparative Example 4, that is, the COP size is 100 nm or less, but the density is 3 × 10 ⁶ atoms / cm 3. The range of the crystal region that does not satisfy the condition of ³ or less is schematically shown.

<Comparative test 4 and evaluation>
About the wafer of Example 2 and Comparative Examples 2-4, the oxidation heat processing hold | maintained at the temperature of 1100 degreeC in the atmosphere of 100% oxygen gas for 4 hours was performed. The yield of GOI before and after this oxidation heat treatment was determined by a TZDB (Time Zero Dielectric Breakdown) method. The yield of GOI is broken down by forming a gate oxide film (oxide film) and electrode on a silicon wafer to produce a MOS (Metal Oxide Semiconductor) structure, and then applying a voltage to the electrode to destroy the gate oxide film. It was determined by measuring the voltage. Here, the dielectric breakdown of the gate oxide film occurred at the defective portion of the wafer. The specific measurement of the breakdown voltage of the gate oxide film by the TZDB method was performed as follows. First, a gate oxide film (SiO ₂ ) having a thickness of 25 nm was formed on the wafer surface. Next, a polysilicon electrode having a gate electrode area of 10 mm ² was formed on the gate oxide film. Further, a voltage was applied between the wafer and the polysilicon electrode by a step voltage application method, and finally a voltage having a judgment electric field strength of 11 MV / cm was applied. The measurement temperature was room temperature (25 ° C.). The results are shown in FIGS.

  As apparent from FIGS. 5 and 6, in the wafers of Comparative Examples 2 to 4, although the GOI yield was slightly improved by the oxidation heat treatment, the GOI yield after the oxidation heat treatment was about 80% in all cases, In the wafer of Example 2, the GOI yield was improved to 100%. In addition, using an infrared scattering tomograph (manufactured by Mitsui Kinzoku Co., Ltd .: MO441), the occurrence of COP was confirmed for the wafers of Comparative Example 4 and Example 2 after the oxidation heat treatment. However, no COP was observed on the wafer of Example 2.

<Example 3>
In the above comparative test 1, a single crystal (13 × 10 ¹⁷ atoms / cm ³ ) having a high oxygen concentration is vertically divided to reveal defects on the evaluation sample surface. A wafer was cut out from a portion of a silicon single crystal (3 × 10 ¹⁷ atoms / cm ³ ) corresponding to the −2-1] region and having a low oxygen concentration. This wafer was referred to as Example 3. The [B-2-1] region means that a COP generation region, an OSF ring, and a defect-free region exist in this order from the center in the radial direction of the single crystal toward the outer periphery.
<Example 4>
In the above comparative test 1, a single crystal (13 × 10 ¹⁷ atoms / cm ³ ) having a high oxygen concentration is vertically divided to reveal defects on the evaluation sample surface. The wafer was cut out from a portion of a silicon single crystal having a low oxygen concentration (3 × 10 ¹⁷ atoms / cm ³ ) corresponding to the −2-2] region. This wafer was referred to as Example 4. The [B-2-2] region means that a COP generation region exists in the center of the single crystal in the radial direction, and an OSF ring exists in the outer peripheral portion in the radial direction.
<Example 5>
In the above comparative test 1, a single crystal (13 × 10 ¹⁷ atoms / cm ³ ) having a high oxygen concentration is vertically divided to reveal defects on the evaluation sample surface. A wafer was cut out from a portion of a silicon single crystal having a low oxygen concentration (3 × 10 ¹⁷ atoms / cm ³ ) corresponding to the -2-3] region. This wafer was referred to as Example 5. The [B-2-3] region means that a COP region is present on the entire surface in the radial direction of the single crystal.

<Comparative Example 5>
In the above comparative test 1, a single crystal (13 × 10 ¹⁷ atoms / cm ³ ) having a high oxygen concentration is vertically divided to reveal defects on the evaluation sample surface. A wafer was cut out from a portion of a silicon single crystal having a low oxygen concentration (3 × 10 ¹⁷ atoms / cm ³ ) corresponding to the −1-1] region. This wafer was designated as Comparative Example 5. Note that the [B-1-1] region is a COP generation region (region where the COP density exceeds 3 × 10 ⁶ atoms / cm ³ ) on the faster pulling speed side of the [B-1] region. To do.
<Comparative Example 6>
In the above comparative test 1, a single crystal (13 × 10 ¹⁷ atoms / cm ³ ) having a high oxygen concentration is vertically divided to reveal defects on the evaluation sample surface. The wafer was cut out from a portion of a silicon single crystal having a low oxygen concentration (3 × 10 ¹⁷ atoms / cm ³ ) corresponding to the −1-2] region. This wafer was designated as Comparative Example 6. Note that the [B-1-2] region means a COP generation region (region closer to the [B-2] region) on the slow pulling speed side in the [B-1] region.

<Comparative test 5 and evaluation>
For the wafers of Examples 3 to 5 and Comparative Examples 5 and 6, the GOI yield was determined in the same manner as in Comparative Test 4 above. This comparative test 5 was conducted to further verify the effectiveness of each crystal region. The results are shown in FIGS. As is clear from FIG. 7, in Comparative Examples 5 and 6, the GOI yield after the oxidation heat treatment was as low as about 80%, whereas in the wafers of Examples 3 to 5, both were after the oxidation heat treatment. GOI yield improved to 100%. Moreover, when the generation | occurrence | production state of COP was confirmed about the wafer of Examples 3-5 after oxidation heat processing using the infrared-scattering tomograph (Mitsui Metals make: MO441), all COP was not observed.

<Examples 6 and 7>
After pulling up the silicon single crystal under the condition of V / G when the wafer of Example 2 was produced, the silicon single crystal was irradiated with neutrons. Then, after slicing the top and bottom of the straight body portion of this silicon single crystal to produce two wafers, these wafers were held at 1000 ° C. for 10 minutes in an oxidizing atmosphere. A wafer obtained by slicing the top of the straight body part was designated as Example 6, and a wafer obtained by slicing the bottom of the straight body part was designated as Example 7. Except that V / G was constant, two wafers were produced under the same conditions as when the silicon single crystal pulled using the apparatus of Example 1 was sliced to obtain the wafer of Example 2. .
<Examples 8 and 9>
Pulling up the silicon single crystal under the same conditions as in Examples 6 and 7, irradiating this silicon single crystal with neutrons, slicing the top and bottom of the straight body of this silicon single crystal, and producing two wafers, These wafers were held at 1000 ° C. for 10 minutes in an oxidizing atmosphere. A wafer obtained by slicing the top of the straight body part was designated as Example 8, and a wafer obtained by slicing the bottom of the straight body part was designated as Example 9.
<Comparative Examples 7 and 8>
Two wafers were obtained in the same manner as in Examples 6 and 7, except that the silicon single crystal was not irradiated with neutrons. A wafer obtained by slicing the top of the straight body was designated as Comparative Example 7, and a wafer obtained by slicing the bottom of the straight body was designated as Comparative Example 8.
<Comparative Examples 9 and 10>
Two wafers were obtained in the same manner as in Examples 8 and 9, except that the silicon single crystal was not irradiated with neutrons. A wafer obtained by slicing the top of the straight body was designated as Comparative Example 9, and a wafer obtained by slicing the bottom of the straight body was designated as Comparative Example 10.

<Comparative test 6 and evaluation>
The in-plane distribution of the resistivity in the radial direction of the silicon wafers of Examples 6 to 9 and Comparative Examples 7 to 10 was measured, and variations in the in-plane resistivity were calculated from the measured values. Specifically, the position is 5 mm inside from the left edge of the wafer, the intermediate position between the left edge and the center of the wafer, the center of the wafer, the intermediate position between the right edge and the center of the wafer, and 5 mm inside from the right edge of the wafer. After measuring the resistivity at each position and calculating the distribution width of these measured values, the distribution width was divided by the minimum value of the measured values and multiplied by 100 to calculate the variation in in-plane resistivity. The resistivity was measured by a 4-probe method. These results are shown in FIG. 9 and FIG. As is apparent from FIG. 9, in the wafers of Comparative Examples 7 and 8 that were not irradiated with neutrons, the radial resistivity distribution width was about 1400 Ω · cm (in-plane resistivity variation: about 36%) and about 2400 Ω. * Cm (in-plane resistivity variation: about 85%), whereas in the wafers of Examples 6 and 7 irradiated with neutrons, the radial resistivity distribution width is about 1.6 Ω.cm (In-plane resistivity variation: about 3.2%) and about 1.2 Ω · cm (in-plane resistivity variation: about 2.5%). Further, as apparent from FIG. 10, in the wafers of Comparative Examples 9 and 10 that were not irradiated with neutrons, the radial resistivity distribution width was about 2300 Ω · cm (in-plane resistivity variation: about 10%) and about In contrast to the very large 1400 Ω · cm (in-plane resistivity variation: about 36%), in the wafers of Examples 8 and 9 irradiated with neutrons, the radial resistivity distribution width is about 2.2 Ω · cm. It was as extremely small as cm (in-plane resistivity variation: about 4.5%) and about 2.1 Ω · cm (in-plane resistivity variation: about 4.2%). That is, in the wafers of Examples 6 to 9, it was within the target range of variation in the in-plane resistivity in the radial direction, that is, within 5%.

<Examples 10 and 11>
1, using a crucible 13 having an inner diameter of 24 inches (about 600 mm), 170 kg of polycrystalline silicon raw material is filled and melted. Each of the silicon single crystals 11 having a crystal orientation of <100> and a diameter of 210 mm was pulled up. The silicon single crystal pulled at a pulling rate of 80% was designated as Example 10, and the silicon single crystal pulled at a pulling rate of 95% was designated as Example 11. After pulling up these silicon single crystals, the silicon single crystals were irradiated with neutrons so that the in-plane resistivity was 50 Ω · cm. Other pulling conditions were as follows. Of the temperature gradient in the pulling axis direction of the single crystal 11 in the temperature range from the melting point to 1370 ° C. of the center portion of the silicon single crystal 11 being pulled, the temperature gradient at the center portion of the single crystal 11 is Gc. When the temperature gradient of the outer peripheral portion is Ge, the hot zone B of FIG. 2 that satisfies the relationship of Gc / Ge ≧ 1, specifically, the relationship of Gc / Ge = 1.2, was used. The pulling rate was adjusted so that V / G was in the range of 0.23 to 0.33, and a horizontal magnetic field of 0.3 T was applied to the silicon melt 15 in the crucible 13. Furthermore, the rotational speed of the crucible was 0.3 rpm.

<Comparative test 7 and evaluation>
The interstitial oxygen concentrations of a plurality of wafers obtained by cutting the straight body portions of the silicon single crystals of Examples 10 and 11 so as to have a predetermined thickness with a certain interval in the pulling direction were measured. The interstitial oxygen concentration was measured according to the Fourier transform infrared spectrophotometry standardized by ASTM F-121 (1979). The result is shown in FIG. As is apparent from FIG. 11, in Example 11, a crystal portion having an interstitial oxygen concentration exceeding 6.0 × 10 ¹⁷ atoms / cm ³ is grown in the latter half of the straight body portion of the silicon single crystal (with a pulling rate of 80% or more). In contrast, in Example 10, the oxygen concentration in the silicon single crystal was almost uniform regardless of the position in the pulling direction of the silicon single crystal. That is, under this pulling condition, a silicon single crystal having an interstitial oxygen concentration of 6.0 × 10 ¹⁷ atoms / cm ³ or less over the entire length of the straight body is obtained by pulling the silicon single crystal within a pulling rate of 80% or less. I found out that I can train it. After the pulling of the silicon single crystal of Example 10 was completed and the silicon single crystal was taken out, the silicon melt remaining in the crucible was filled again with the polycrystalline silicon raw material to obtain the same melt amount as in Example 10. The silicon single crystal was grown again under the same conditions as in Example 10 (grown by the multiple pulling method). The oxygen concentration distribution of this silicon single crystal was almost the same as the oxygen concentration distribution of the silicon single crystal of Example 10. Met.

<Comparative test 8 and evaluation>
The silicon single crystal 11 was pulled up using the pulling apparatus shown in FIG. Of the temperature gradient in the pulling axis direction of the single crystal 11 in the temperature range from the melting point to 1370 ° C. of the central portion of the silicon single crystal 11 being pulled, the temperature gradient at the central portion of the single crystal 11 is Gc. 2 is used, which satisfies the relationship of Gc / Ge ≧ 1, specifically, the relationship of Gc / Ge = 1.2. The pulling speed was adjusted so that V / G was in the range of 0.23 to 0.33. Further, phosphorus is added to the silicon raw material so that the silicon melt 15 contains phosphorus so that the in-plane resistivity in the radial direction at the position of the straight body top of the pulled single crystal 11 is 100 Ω · cm. A 0.2 T horizontal magnetic field was applied to the silicon melt 15 in the crucible 13. Furthermore, the diameter of the single crystal was 210 mm, the crystal orientation of the single crystal was <100>, and the length of the straight body portion of the single crystal was 1700 mm. On the other hand, the rotation speed of the crucible is set to 6 levels of 0.1 rpm, 0.3 rpm, 0.7 rpm, 1.0 rpm, 1.7 rpm and 2.0 rpm, and the rotation speed of the single crystal is set to 8 levels of 1 to 8 rpm. The silicon single crystal was pulled up while rotating in the reverse direction. The interstitial oxygen concentration in the wafer cut out at a position of 200 mm from the top of the straight body portion of these silicon single crystals was measured. The interstitial oxygen concentration was measured according to the Fourier transform infrared spectrophotometry standardized by ASTM F-121 (1979). The result is shown in FIG.

As is apparent from FIG. 12, when the rotational speed of the crucible is 1.5 rpm or less and the rotational speed of the single crystal is 7 rpm or less, the interstitial oxygen concentration in the wafer is 6.0 × 10 ¹⁷ atoms / cm. It turned out that it can be made ³ or less.

11 Silicon single crystal 12 Main chamber (chamber)
13 crucible 15 silicon melt 22 pulling shaft 23 seed crystal 29 horizontal magnetic field 52 silicon raw material

Claims (5)

A silicon melt is stored in a crucible accommodated in a chamber, a seed crystal is immersed in the silicon melt, the silicon single crystal is pulled up while rotating, and then the silicon single crystal is irradiated with neutrons to irradiate the silicon single crystal. In the method for producing a silicon single crystal in which the crystal is doped with phosphorus,
From the crucible, a silicon single crystal having an internal interstitial oxygen concentration of 6.0 × 10 ¹⁷ atoms / cm ³ or less, having a size of 100 nm or less and a density of 3 × 10 ⁶ atoms / cm ³ or less. After pulling up a silicon single crystal including a COP generation region,
A method for producing a silicon single crystal, wherein the variation of in-plane resistivity in the radial direction of the silicon single crystal is reduced to 5% or less by irradiating the silicon single crystal with neutrons.   Of the temperature gradient in the pulling axis direction of the silicon single crystal in the temperature range from the melting point to 1370 ° C. of the center portion of the silicon single crystal being pulled, the temperature gradient of the center portion of the silicon single crystal being pulled is Gc, 2. The method for producing a silicon single crystal according to claim 1, wherein the silicon single crystal is pulled under conditions satisfying a relationship of Gc / Ge ≧ 1, where Ge is a temperature gradient of the outer peripheral portion of the silicon single crystal being pulled. After pulling up the silicon single crystal so that the interstitial oxygen concentration in the silicon single crystal is 6.0 × 10 ¹⁷ atoms / cm ³ or less over the entire length, the silicon raw material is supplied into the crucible and melted, The silicon single crystal is newly pulled from the silicon melt to pull up a plurality of silicon single crystals, and each silicon single crystal after the pulling is irradiated with neutrons to dope the silicon single crystal The method for producing a silicon single crystal according to claim 1.   A horizontal magnetic field of 0.2 T or more is applied to the silicon melt in the crucible, the rotation speed of the crucible is 1.5 rpm or less, and the rotation speed of the silicon single crystal being pulled is 7 rpm or less. 3. The method for producing a silicon single crystal according to any one of 3 above.   A silicon wafer obtained by slicing a silicon single crystal produced by the method according to any one of claims 1 to 4, is heated to a predetermined temperature within a range of 1100 to 1300 ° C in an oxygen gas atmosphere. A method for producing a silicon wafer, wherein the COP is extinguished over the entire area of the silicon wafer by performing a heat treatment that is maintained at the predetermined temperature for 2 to 5 hours.

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