Process for producing an n-type silicon single crystal

Abstract

A method for producing an n-type silicon single crystal (10), comprising pulling up a silicon single crystal (10) from a silicon melt (9) in a crucible (3A) containing red phosphorus as the main dopant and growing the silicon single crystal (10) using the Czochralski process, the method comprising: controlling the specific electrical resistance at a starting position of the straight body part of the silicon single crystal (10) to 0.80 mΩcm or more and 1.05 mΩcm or less; and sequentially reducing the specific electrical resistance of the silicon single crystal (10) as the silicon single crystal (10) is pulled up and grown, to thereby regulate the specific electrical resistance of a part of the silicon single crystal (10) to 0.5 mΩcm or more and 0.7 mΩcm or less, wherein the inner diameter of the crucible (3A) is 1.7 times or more and 2.3 times or less than the diameter of the straight body of the silicon single crystal (10) during pulling up.

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for producing an n-type silicon single crystal. STATE OF THE ART

[0002] In recent years, mobile devices such as mobile phones have become widely used. There is a strong demand for such portable devices to be worn and used for long periods of time, and efforts have been made to increase the capacity of a battery built into the portable device and reduce the power consumption of the portable device itself.

[0003] In order to reduce the power consumption of the portable device itself, it is necessary to reduce the power consumption of a semiconductor element built into the portable device.

[0004] For example, a low breakdown voltage power MOSFET (metal oxide semiconductor field effect transistor) used as a power device for a portable device has a certain internal electrical resistance when it is turned on, and so the low breakdown voltage power MOSFET itself consumes energy depending on the current flowing through the low breakdown voltage power MOSFET.

[0005] Accordingly, if the internal resistance of the low-breakdown voltage power MOSFET can be reduced in the on-state, the power consumption of the portable device can be reduced. Against this background, there has been a strong demand for an n-type silicon single crystal with low electrical resistivity (hereinafter referred to as low resistivity) to reduce the resistance when the low-breakdown voltage power MOSFET is on.

[0006] In typical silicon single crystal manufacturing processes, the silicon single crystal is pulled up to a target value while controlling the electrical resistivity (hereinafter referred to as resistivity) so that the silicon single crystal has a constant electrical resistivity throughout.

[0007] It is known that when such a low-resistivity silicon single crystal is produced by pulling according to the Czochralski process or the like, dislocations easily occur in the silicon single crystal during pulling up.

[0008] Patent Literature 1 discloses a technique to prevent the occurrence of dislocations at a tail part by increasing the resistivity in the tail part while paying attention to the fact that the dopant concentration in the tail part increases immediately before the completion of pulling up a silicon single crystal, and that abnormal growth occurs due to compositional supercooling. [Citation list][Patent literature]

[0009] [Patent Literature 1] Japanese Patent Application JP 2010-184839 A

[0010] Further prior art can be found in US 20110140241 A1, which describes a method for producing silicon ingots, among other things, in DE 11 2016 001 962 T5, which describes a method for producing silicon epitaxial wafers, in DE 11 2017 006 524 T5, which describes a method for producing silicon single crystal, heat shield and single crystal pulling device and in DE 11 2015 005 768 T5, which describes a method for producing monocrystal. SUMMARY OF THE INVENTION [Problems to be solved by the invention]

[0011] When the technique described in Patent Literature 1 is used to pull up an n-type silicon single crystal with low resistivity, n-type dopants such as red phosphorus and arsenic, which are volatile dopants, are evaporated during pulling up, and thus it is not possible to manufacture a silicon single crystal whose resistivity is within a desired low resistivity range, or dislocations occur in a part at the beginning of the straight body of the silicon single crystal depending on an increase in the amount of n-type dopants added.

[0012] In this case, a seed crystal is brought into contact with a melt in a crucible and the pulling up is carried out again, but if the pulling up is repeated, the manufacturing cost of the silicon single crystal ingot increases.

[0013] It is an object of the invention to provide a method for producing an n-type silicon single crystal which can provide an n-type silicon single crystal having a low resistivity without increasing the manufacturing cost, an n-type silicon single crystal ingot, a silicon wafer and an epitaxial silicon wafer. [Means of solving the tasks]

[0014] The invention focuses on the occurrence of dislocations at a starting position of the straight body part, and it is an object of the invention to prevent the occurrence of dislocations at the starting position of the straight body part by making the resistivity at the starting position of the straight body part larger than a target value and then sequentially decreasing the resistivity.

[0015] The present invention is defined by the manufacturing methods according to claims 1 and 2.

[0016] More specifically, according to one aspect of the invention, there is provided a method for producing an n-type silicon single crystal by pulling up a silicon single crystal from a silicon melt containing volatile red phosphorus as a main dopant and growing the silicon single crystal by the Czochralski process, the method comprising the steps of: controlling the electrical resistivity at a starting position of the straight body part of the silicon single crystal to 0.8 mΩcm or more and 1.05 mΩcm or less; and sequentially decreasing the electrical resistivity of the silicon single crystal as the silicon single crystal is pulled up and grown, to thereby control the electrical resistivity of a part of the silicon single crystal to 0.5 mΩcm or more and 0.7 mΩcm or less.

[0017] According to the above aspect of the invention, since it is possible to prevent the occurrence of dislocations at the starting position of the straight body part by controlling the resistivity at the starting position of the straight body part of the silicon single crystal to 0.8 mΩcm or more and 1.05 mΩcm or less, it is possible to avoid repeated pulling up of the silicon single crystal, and thus it is possible to manufacture a red phosphorus-doped silicon single crystal having low resistivity without increasing the manufacturing cost.

[0018] According to a further aspect not according to the invention, there is provided an ingot of an n-type silicon single crystal containing red phosphorus as a main dopant, wherein the specific electrical resistance of a part of the silicon single crystal is 0.5 mΩcm or more and less than 0.6 mΩcm.

[0019] According to a further aspect not according to the invention, there is provided a silicon wafer cut from the ingot of the n-type silicon single crystal and having a specific electrical resistance of 0.5 mΩcm or more and less than 0.6 mΩcm.

[0020] According to another aspect not according to the invention, there is provided an epitaxial silicon wafer including: the silicon wafer; and an epitaxial growth film formed on a surface of the silicon wafer.

[0021] According to the above non-inventive aspects, since it is possible to produce an ingot, a silicon wafer, and an epitaxial silicon wafer of a red phosphorus-doped silicon single crystal having a low resistivity of 0.5 mΩcm or more and less than 0.6 mΩcm at low cost, they can be offered to a customer at lower prices.

[0022] According to another aspect of the invention, there is provided a method for producing an n-type silicon single crystal, which comprises pulling up a silicon single crystal from a silicon melt containing volatile arsenic as a main dopant and growing the silicon single crystal by the Czochralski process, including the steps of: controlling a specific electrical resistance at a starting position of the straight body part of the silicon single crystal to 1.9 mΩcm or more and 2.3 mΩcm or less; and sequentially decreasing the specific electrical resistance of the silicon single crystal as the silicon single crystal is pulled up and grown, to thereby control the specific electrical resistance of a part of the silicon single crystal to 1.2 mΩcm or more and 1.4 mΩcm or less.

[0023] According to the above aspect of the invention, it is possible to produce an arsenic-doped silicon single crystal having a low resistivity without increasing the manufacturing cost by the same advantages and effects as described above.

[0024] According to another aspect not according to the invention, there is provided an ingot of an n-type silicon single crystal containing arsenic as a main dopant, wherein the specific electrical resistance of a part of the silicon single crystal is 1.2 mΩcm or more and 1.4 mΩcm or less.

[0025] According to another aspect not according to the invention, there is provided a silicon wafer cut from the ingot of the n-type silicon single crystal and having an electrical resistivity of 1.2 mΩcm or more and 1.4 mΩcm or less.

[0026] According to another aspect not according to the invention, there is provided an epitaxial silicon wafer including: the silicon wafer; and an epitaxial growth film formed on a surface of the silicon wafer.

[0027] According to the above non-inventive aspects, it is possible to offer an ingot and a silicon wafer of a low-resistivity arsenic-doped silicon single crystal to a customer at low prices by the same advantages and effects as described above. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram showing an example of a structure of a silicon single crystal pulling-up apparatus according to an embodiment not according to the present invention; Fig.2 is a graph showing the relationship between a length of the straight body and a resistivity of a silicon single crystal when red phosphorus is used as a dopant in the embodiment; Fig. 3 is a graph showing the relationship between the length of the straight body of the silicon single crystal and the occupancy [%] (denominator: total number of trials, numerator: number of trials with dislocations or number of trials without dislocations over the total length) when red phosphorus is used as a dopant in the embodiment; Fig. 4 is a graph showing the relationship between a length of the straight body and the resistivity of a silicon single crystal when arsenic is used as a dopant in the embodiment; and Fig.5 is a graph showing the relationship between the length of the straight body of the silicon single crystal and the occupancy [%] (denominator: total number of trials, numerator: number of trials with dislocations or number of trials without dislocations over the total length) when arsenic is used as a dopant in the embodiment. DESCRIPTION OF EMBODIMENTS[1] Structure of the silicon single crystal pulling device 1

[0028] Fig. 1 is a schematic diagram showing an example of the structure of a silicon single crystal pulling apparatus 1 for performing a method for producing an n-type silicon single crystal according to an embodiment of the invention. The pulling apparatus 1 is equipped with a chamber 2 forming an outer shell and a crucible 3 arranged in a central region of the chamber 2.

[0029] The crucible 3 has a double structure composed of an inner quartz crucible 3A and an outer graphite crucible 3B, and is fixed to an upper end of a support shaft 4 which can rotate and lift.

[0030] According to the invention, the inner diameter of the quartz crucible 3A inside the crucible 3 is 1.7 times or more and 2.3 times or less than the diameter of the straight body of the silicon single crystal 10 during pulling up.

[0031] Specifically, when the diameter of the straight body of the silicon single crystal 10 is 201 mm or more and 230 mm or less, the inner diameter of the quartz crucible 3A is preferably 2.1 times or more and 2.3 times or less of the diameter of the straight body of the silicon single crystal 10. When the diameter of the straight body of the silicon single crystal 10 is 301 mm or more and 330 mm or less, the inner diameter of the quartz crucible 3A is preferably 1.7 times or more and 2.0 times or less of the diameter of the straight body of the silicon single crystal 10.

[0032] A resistance heater 5 surrounding the crucible 3 is mounted outside the crucible 3, and a heat insulating material 6 is provided along an inner surface of the chamber 2 outside the heater 5.

[0033] A pull shaft 7, for example, a wire rotating at a fixed speed in the opposite or same direction coaxial with the support shaft 4, is provided above the crucible 3. A seed crystal 8 is attached to a lower end of the pull shaft 7.

[0034] A cylindrical heat shielding plate 12 is arranged in the chamber 2.

[0035] The heat shielding plate 12 functions to shield the growing silicon single crystal 10 from high-temperature radiant heat from the silicon melt 9 in the crucible or the heater 5 or a side wall of the crucible 3, and functions, with respect to the vicinity of a solid-liquid interface, which is a crystal growth interface, to suppress the diffusion of heat to the outside and to control the temperature gradients of a central region and an outer peripheral region of the silicon single crystal toward the pull shaft.

[0036] A gas inlet port 13 for introducing an inert gas, such as Ar gas, into the chamber 2 is provided in an upper part of the chamber 2. An exhaust port 14 for exhausting and discharging the gas in the chamber 2 by operating a vacuum pump (not shown) is provided in a lower part of the chamber 2.

[0037] The inert gas supplied through the gas inlet port 13 into the chamber 2 moves downward between the growing silicon single crystal 10 and the heat-shielding plate 12, flows toward the outside of the heat-shielding plate 12, and further toward the outside of the crucible 3 after passing through a gap (liquid level gap) between a lower end of the heat-shielding plate 12 and a liquid level of the silicon melt 9. Then, the inert gas moves downward along the outside of the crucible 3 and is exhausted through the exhaust port 14.

[0038] When growing the silicon single crystal 10 using such a growth apparatus, a solid raw material, such as polycrystalline silicon, filled in the crucible 3 is melted by heating with the heater 5 while maintaining the interior of the chamber 2 under reduced pressure in an inert gas atmosphere, thus forming the silicon melt 9. When the silicon melt 9 is formed in the crucible 3, the pulling shaft 7 is moved downward, and the seed crystal 8 is immersed in the silicon melt 9. While rotating the crucible 3 and the pulling shaft 7 in a predetermined direction, the pulling shaft 7 is gradually pulled up. Accordingly, a silicon single crystal 10 bonded to the seed crystal 8 grows. [2] Process for producing the silicon single crystal 10

[0039] When manufacturing the silicon single crystal 10 according to this embodiment using the above-described pulling-up apparatus 1, the silicon single crystal can be manufactured by appropriately adding red phosphorus or arsenic as a main dopant to the silicon melt 9 at the beginning or during pulling-up. When red phosphorus or arsenic is used as the main dopant, it accounts for 50 mass% or more of the n-type dopant, and other dopant additions may be made.

[0040] When red phosphorus is used as a dopant, the resistivity at a starting position of the straight body part of the silicon single crystal 10 is controlled to be 0.80 mΩcm or more and 1.05 mΩcm or less. Then, the resistivity of the silicon single crystal 10 is sequentially decreased as the silicon single crystal 10 is pulled up and grown, and finally, a silicon single crystal 10 with a resistivity of 0.5 mΩcm or more and 0.7 mΩcm or less, and particularly less than 0.6 mΩcm, at an end part of a length of the straight body is obtained.

[0041] Similarly, when arsenic is used as a dopant, the resistivity at the starting position of the straight body part of the silicon single crystal 10 is controlled to 1.90 mΩcm or more and 2.30 mΩcm or less. Then, the resistivity of the silicon single crystal 10 is sequentially decreased as the silicon single crystal 10 is pulled up and grown, and ultimately, a silicon single crystal with a resistivity of 1.2 mΩcm or more and 1.4 mΩcm or less is obtained.

[0042] The silicon single crystal ingot 10 according to this embodiment can be pulled up under general pulling-up conditions. In this case, examples of measures to increase the concentration of the dopant, such as red phosphorus or arsenic, in the silicon melt 9 in the crucible 3 include adding dopant during pulling up, taking advantage of an increase in the dopant concentration due to a segregation phenomenon accompanying the pulling up, suppressing the evaporation of the dopant by changing the amount of the inert gas introduced into the chamber 2, and changing the pressure in the chamber 2.

[0043] Especially in the first half of pulling up the straight body part of the silicon single crystal 10, when it is necessary to suppress the evaporation of the dopant and increase the dopant concentration in the silicon melt 9 in the crucible 3, the Ar flow rate is 50 L / min to 150 L / min and the furnace pressure is 40 kPa to 80 kPa.

[0044] Meanwhile, in the second half of pulling up the straight body part of the silicon single crystal 10, when it is necessary to promote the evaporation of the dopant and maintain the dopant concentration in the silicon melt 9 in the crucible 3 by compensating for an increase in the dopant concentration due to segregation accompanying the progress of the growth of the silicon single crystal 10, the Ar flow rate is 50 L / min to 200 L / min and the furnace pressure is 20 kPa to 80 kPa.

[0045] As for the part of the silicon single crystal 10 pulled up with the pull-up device 1, when red phosphorus is used as a dopant, an ingot of a silicon single crystal 10 having a resistivity of 0.5 mΩcm or more and less than 0.6 mΩcm at a part near the tail of the silicon single crystal 10 is obtained.

[0046] A silicon wafer having a resistivity of 0.5 mΩcm or more and less than 0.6 mΩcm can be obtained by cutting out the above part to the silicon wafer with a wire saw or the like, and subjecting the cut-out silicon wafer to a lapping step and a polishing step.

[0047] In addition, an annealing heat treatment is performed after silicon wafer processing, and then an epitaxial growth film is formed on a surface of the silicon wafer to manufacture an epitaxial silicon wafer and deliver it to customers.

[0048] When arsenic is used as a dopant, a silicon single crystal 10 having a resistivity of 1.2 mΩcm or more and 1.4 mΩcm or less at a part near the tail of the silicon single crystal 10 is obtained.

[0049] The above part is cut into a silicon wafer using a wire saw or the like. The cut silicon wafer undergoes a lapping and polishing step and is then delivered to the customer. If necessary, the customer can apply an epitaxial growth film and fabricate a semiconductor. [Examples]

[0050] When pulling up a silicon single crystal 10 having a crystal diameter of 201 mm to 231 mm, in the examples, the ratio of the inner diameter of the crucible 3 to the crystal diameter (= inner diameter of the crucible 3 / crystal diameter) was 1.8 to 2.3, the feed amount was 80 kg to 180 kg, the pulling speed was 0.3 mm / min to 1.0 mm / min, and the crystal rotation speed was 9 rpm to 17 rpm.

[0051] In the first half of the straight body part of the silicon single crystal 10, the argon gas flow rate was 50 L / min to 150 L / min, and the furnace pressure was 40 kPa to 80 kPa. In the second half of the straight body part of the silicon single crystal 10, the Ar flow rate was 50 L / min to 200 L / min, and the furnace pressure was 20 kPa to 80 kPa. [1] Use of red phosphorus as a dopant

[0052] While controlling the resistivity by adding red phosphorus as a dopant, changing the Ar flow rate, the furnace pressure, or the position of the height of a heat-shielding plate 12 from the liquid level, changing the speed at which the silicon single crystal 10 was pulled up, or a combination thereof depending on a position in the straight body length of the silicon single crystal 10, the red phosphorus-doped silicon single crystal 10 was pulled up. The results of this are shown in Table 1 and Fig. 2. In the following description, the length of the straight body 0% position means the starting position of the straight body part of the silicon single crystal 10, and the length of the straight body 100% position means the starting position of the tail of the silicon single crystal 10. [Table 1] Comparative Example 1 Example 1 Example 2 Compare Example 2 Specific resistance [mΩcm] Length of the straight body-0% position (end of the shoulder) 1, 2 1,05 0, 8 0,75 Length of the straight body-20% position 1,05 0,92 0,73 It was not possible to Length of the straight 0,92 0, 8 0,66 Body 40% position to obtain single crystal Length of the straight body-60% position 0,82 0,7 0,61 Length of the straight body-80% position 0,75 0,63 0,56 Length of the straight body-100% position (starting position of the tail) 0,7 0,58 0,52

[0053] Additionally, each case was examined for dislocations. The results are shown in Table 2 and Fig. 3. The diameter of the silicon single crystal was controlled within a range of 201 mm or more and 230 mm or less to obtain a single crystal for a 200 mm wafer. In Table 2, an acceptable length for the straight body is a value obtained by dividing the length of the region of the straight body where the resistivity is acceptable and no dislocations exist over the entire length of the straight body, and occupancy is the number of trials with dislocations / total number of trials or the number of trials without dislocations in the entire length / total number of trials. [Table 2] Comparative Example 1 Example 1 Example 2 Compare Example 2 Occupancy (number of attempts / number of attempts) Shoulder up to 80 mm 5 % 22 % 44 % 93 % 80 mm up to 20% 0 % 11 % 11 % 7 % 20% to 40% 0 % 0 % 0 % 0 % 40% to 60% 0 % 0 % 0 % 0 % 60% to 80% 0 % 0 % 0 % 0 % 80% to 100% 0 % 11 % 11 % 0 % tail 45 % 22 % 11 % 0 % Percentage without dislocations over the entire crystal length (number of attempts / number of attempts) 50 % 33 % 22 % 0 % Number of pull-up attempts 20 9 9 15 Acceptable length of the straight body (0.7 mΩcm or less) 0 % 40 % 70 % 0 % Acceptable length of the straight body (less than 0.6 mΩcm) 0 % 10 % 35 % 0 %

[0054] As can be seen from Table 2 and Fig.As can be seen from Figure 3, in the silicon single crystal of Comparative Example 1, the rate of dislocation occurrence up to 80 mm from the starting position of the straight body part is 5%. This means that the occurrence of dislocations can be prevented with a high probability. As shown in Table 1 and Fig. 2, the resistivity stops decreasing even at a straight body length 100% position to 0.7 mΩcm, and thus a low resistivity silicon single crystal having a resistivity of 0.7 mΩcm or less cannot be manufactured.

[0055] As can be seen from Table 1 and Fig. 2, in the silicon single crystal of Comparative Example 2, dislocations occurred continuously from 80 mm away from the starting position of the straight body part to a straight body length 20% position, and a silicon single crystal could not be produced.

[0056] In contrast, it was confirmed that the resistivity of the silicon single crystal of Example 1 can be reduced to 0.7 mΩcm or less at a position 60% from the starting position of the straight body part, the rate of dislocation occurrence at a position 80 mm away from the starting position of the straight body part can be suppressed to 22%, and thus a silicon single crystal with a low resistivity of 0.7 mΩcm or less can be manufactured. In particular, it was confirmed that a single crystal with an extremely low resistivity of less than 0.6 mΩcm, which could not be manufactured until now, can be manufactured in 90% or more of the length of the straight body.

[0057] Similarly, it was confirmed that the resistivity of the silicon single crystal of Example 2 can be reduced to 0.7 mΩcm or less at a position 30% from the starting position of the straight body part, the rate of dislocation occurrence at a position 80 mm away from the starting position of the straight body part can be suppressed to 44%, and thus a silicon single crystal with a low resistivity of 0.7 mΩcm or less is produced. In particular, it was confirmed that a single crystal with an extremely low resistivity of less than 0.6 mΩcm, which could not be produced until now, can be produced in 65% or more of the length of the straight body. [2] Use of arsenic as a dopant

[0058] While controlling the resistivity by adding arsenic as a dopant depending on a position in a length of the straight body of the silicon single crystal, the arsenic-doped silicon single crystal was pulled up. The results are shown in Table 3 and Fig. 4 shown. [Table 3] Compare Example 3 Example 3 Example 4 Compare Example 4 Specific resistance [mΩcm] Length of the straight body-0% position (end of the shoulder) 2,6 2,3 1,9 1, 8 Length of the straight body-20% position 2,2 2 1,66 It was not possible to obtain a single crystal Length of the straight body-40% position 1,95 1,75 1,5 Length of the straight body-60% position 1,75 1,55 1,37 Length of the straight body-80% position 1,6 1,42 1,29 Length of the straight body-100% position (starting position of the tail) 1,5 1,33 1,22

[0059] Additionally, each case was examined for dislocations. The results are shown in Table 4 and Fig. 5 shown. [Table 4] Compare Example 3 Example 3 Example 4 Compare Example 4 Occupancy (number of attempts / number of attempts) Beginning of the straight body up to 80 mm 6 % 9 % 38 % 80 % 80 mm up to 20% 0 % 4 % 10 % 20 % 20% to 40% 0 % 0 % 0 % 0 % 40% to 60% 0 % 0 % 0 % 0 % 60% to 80% 0 % 0 % 0 % 0 % 80% to 100% 0 % 13 % 8 % 0 % tail 31 % 30 % 18 % 0 % Percentage without dislocations over the entire crystal length (number of attempts / number of attempts) 63 % 44 % 26 % 0 % Number of pull-up attempts 16 23 39 10 Acceptable length of the straight body (1.4 mΩcm or less) 0 % 17 % 45 % 0 %

[0060] As can be seen from Table 4 and Fig. 5, the rate of dislocation occurrence is low up to 80 mm from the starting position of the straight body part. Namely, it is 6% in the silicon single crystal of Comparative Example 3, and it is possible to prevent the occurrence of dislocations. However, as can be seen from Table 3 and Fig.4, the resistivity stops decreasing to 1.5 mΩcm even at a straight body length 100% position, and thus a low resistivity silicon single crystal having a resistivity of 1.4 mΩcm or less cannot be manufactured.

[0061] As can be seen from Table 3 and Fig. 4, in the silicon single crystal of Comparative Example 4, dislocations occurred continuously from 80 mm away from the starting position of the straight body part to a straight body length 20% position, and a silicon single crystal could not be produced.

[0062] In contrast, it was confirmed that the resistivity of the silicon single crystal of Example 3 at a position 85% from the starting position of the straight body part could be reduced to 1.4 mΩcm or less, and the rate of occurrence of dislocations at a position 80 mm away from the starting position of the straight body part could be suppressed to 9%, and thus a silicon single crystal with a low resistivity of 1.4 mΩcm or less could be manufactured.

[0063] Similarly, it was confirmed that the resistivity of the silicon single crystal of Example 4 at a position 55% from the starting position of the straight body part can be reduced to 1.4 mΩcm or less, and the rate of occurrence of dislocations at a position 80 mm away from the starting position of the straight body part can be suppressed to 38%, and thus a silicon single crystal with a low resistivity of 1.4 mΩcm or less can be manufactured.

[0064] As described above, when pulling up a silicon single crystal 10 from a silicon melt 9 containing red phosphorus as a dopant by the Czochralski process, when the resistivity of the silicon single crystal 10 at the starting position of the straight body was controlled to 0.80 mΩcm or more and 1.05 mΩcm or less, and then the resistivity of the silicon single crystal 10 was sequentially reduced while the silicon single crystal 10 was pulled up and grown, the resistivity of a part of the silicon single crystal 10 could be controlled to 0.5 mΩcm or more and 0.7 mΩcm or less, and in particular, to an extremely low resistivity of less than 0.6 mΩcm, which could not be obtained until now, and it was possible to suppress the occurrence of dislocations in the silicon single crystal 10.

[0065] Similarly, when pulling up a silicon single crystal 10 from a silicon melt 9 containing arsenic as a dopant by the Czochralski process, if the resistivity of the silicon single crystal at the starting position of the straight body part was controlled to 1.90 mΩcm or more and 2.30 mΩcm or less, and then the resistivity of the silicon single crystal was sequentially decreased while the silicon single crystal 10 was pulled up and grew, the resistivity of a part of the silicon single crystal 10 could be controlled to 1.2 mΩcm or more and 1.4 mΩcm or less, and it was possible to suppress the occurrence of dislocations in the silicon single crystal 10. [List of reference symbols] 1 hoisting device 2 chambers 3 crucibles 3A quartz crucible 3B graphite crucible 4 carrying shaft 5 Heating 6 Thermal insulation material 7 Draw shaft 8 Seed crystal 9 Silicon melt 10 silicon single crystal 11 Heat shielding plate 13 Gas inlet opening 14 Exhaust opening

Claims

A method for producing an n-type silicon single crystal (10), comprising pulling up a silicon single crystal (10) from a silicon melt (9) in a crucible (3A) containing red phosphorus as a main dopant and growing the silicon single crystal (10) by the Czochralski process, the method comprising:controlling the specific electrical resistance at a starting position of the straight body part of the silicon single crystal (10) to 0.80 mΩcm or more and 1.05 mΩcm or less;andsequentially decreasing the electrical resistivity of the silicon single crystal (10) as the silicon single crystal (10) is pulled up and grown, to thereby regulate the electrical resistivity of a part of the silicon single crystal (10) to 0.5 mΩcm or more and 0.7 mΩcm or less, wherein the inner diameter of the crucible (3A) is 1.7 times or more and 2.3 times or less than the diameter of the straight body of the silicon single crystal (10) during the pulling up.; A method for producing an n-type silicon single crystal (10) comprising pulling up a silicon single crystal (10) from a silicon melt (9) in a crucible (3A) containing arsenic as a main dopant and growing the silicon single crystal (10) by the Czochralski process, the method comprising:controlling the electrical resistivity at a starting position of the straight body part of the silicon single crystal (10) to 1.90 mΩcm or more and 2.30 mΩcm or less;andsequentially decreasing the electrical resistivity of the silicon single crystal (10) as the silicon single crystal (10) is pulled up and grown, to thereby regulate the electrical resistivity of a part of the silicon single crystal (10) to 1.2 mΩcm or more and 1.4 mΩcm or less, wherein the inner diameter of the crucible (3A) is 1.7 times or more and 2.3 times or less than the diameter of the straight body of the silicon single crystal (10) during the pulling up.;

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