JP2011157224A - Method for manufacturing silicon single crystal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably prevent generation of deposits during the growth of a tail portion while preventing the quality decrease of a straight trunk portion in the growth of a silicon single crystal. <P>SOLUTION: A pulling-up apparatus 10 is used which has a heater 15 to heat a silicon melt 21 and a heat shield 22 installed between a silicon single crystal 20 and the heater 15. If the distances between the heat shield 22 and a molten metal surface 21a during the growth of a straight trunk portion and a tail portion are taken as A and B, respectively, and the pulling-up speeds during the growth of the straight trunk portion and the tail portion are taken as C and D, respectively, A/B is set at ≥1 and ≤1.6; C/D, at ≥0.6; and a value F of (A/B)×(C/D), ≥0.8 and ≤1.3. Hence, even when a large-diameter crucible, for example, a crucible of ≥850 mm in inner diameter, is used, the generation of deposits and the quality decrease of the straight trunk portion can be stably prevented during the growth of the tail portion. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a silicon single crystal using the Czochralski method (CZ method), and in particular, a silicon single crystal that can prevent silicon melt from being deposited in a quartz crucible when growing a tail portion. It relates to a manufacturing method.

  The CZ method is most widely used as a method for growing a silicon single crystal ingot. The CZ method is a method in which a polycrystalline silicon lump filled in a crucible is heated with a heater to form a silicon melt, and a silicon single crystal is grown by pulling up a seed crystal immersed in the silicon melt. In the growth of a silicon single crystal by the CZ method, a shoulder portion whose diameter is enlarged in the growth direction is formed, then a straight body portion (body portion) having a constant diameter is formed in the growth direction, and finally, the growth direction. A tail portion whose diameter is reduced is formed on the surface. Among these, only the straight body portion is used as a product (silicon wafer), and the shoulder portion and the tail portion are portions that are not used as products. However, the shoulder part is a part necessary for expanding the diameter of the silicon single crystal to a desired diameter, and the tail part is necessary for separating the silicon single crystal from the melt without causing dislocation in the straight body part. Part.

  Since the tail portion is a portion that is not used as a product, the formation thereof is preferably completed in a short time. For this reason, in raising the tail portion, it is generally performed to increase the pulling speed more than in raising the straight body portion. However, in order to increase the pulling speed (that is, to promote solidification), it is necessary to control the amount of heat input from the heater to the silicon melt so that the temperature between the silicon single crystal and the silicon melt is increased. The gradient becomes smaller. As a result, the temperature of the silicon melt locally falls below the melting point, and precipitation (solidification) may occur.

  As a method for solving such a problem, Patent Document 1 discloses a method of narrowing the distance between the thermal shield surrounding the silicon single crystal and the molten metal surface of the silicon melt when growing the tail portion. Yes. If the distance between the heat shield and the melt surface of the silicon melt is reduced, the radiant heat from the heater to the silicon single crystal is reduced, so it is necessary to control the heat input from the heater to the silicon melt. As a result, the temperature gradient between the silicon single crystal and the silicon melt is increased. Thereby, since the temperature of a silicon melt becomes high, generation | occurrence | production of local precipitation is prevented.

JP 2008-120623 A

  However, according to the study of the present inventors, the case where the precipitation cannot be sufficiently prevented simply by narrowing the distance between the thermal shield and the molten metal surface of the silicon melt at the time of growing the tail portion, Although precipitation is prevented, it has been found that there are many cases where the quality of the straight body portion deteriorates. These cases are conspicuous when a large-diameter crucible is used to grow a larger-diameter silicon single crystal. Particularly when a crucible having an inner diameter of 850 mm or more is used, the heat shield and silicon are simply used. Just adjusting the distance of the melt from the molten metal surface makes the control margin too narrow, and it is difficult to stably prevent the occurrence of precipitation and the deterioration of the quality of the straight body.

  Accordingly, an object of the present invention is to provide an improved method for producing a silicon single crystal capable of stably preventing the occurrence of precipitation during the growth of the tail portion while preventing the quality deterioration of the straight body portion. .

  The inventors of the present invention have conducted intensive research to find a pulling condition that does not cause precipitation or deterioration of the quality of the straight body part even when a crucible having a large diameter is used. As a result, in order to stably prevent the occurrence of precipitation and deterioration of the quality of the straight body part during the tail part growth, the distance between the heat shield and the silicon melt surface during the straight body part growth In addition to the relationship (first parameter) between the distance between the heat shield and the melt surface of the silicon melt during the tail growth, the pulling speed and the tail It is found that the relationship between the pulling speed at the time of growth (second parameter) and the relationship between the first parameter and the second parameter (third parameter) must be within a predetermined range. did. The present invention has been made based on such technical knowledge.

  The method for producing a silicon single crystal according to the present invention includes a shoulder portion whose diameter increases in the growth direction by pulling up a seed crystal immersed in a silicon melt in a crucible, and a straight body portion whose diameter is constant in the growth direction. A method of manufacturing a silicon single crystal having a tail portion whose diameter decreases in the growth direction, the heater for heating the silicon melt, and a heat shield provided between the silicon single crystal and the heater And using the pulling device having a body, the distance between the thermal shield and the silicon melt surface when the straight body portion is grown is A, and the thermal shield and the silicon when the tail portion is grown When the distance from the molten metal surface is B, the pulling speed at the time of growing the straight body portion is C, and the pulling speed at the time of growing the tail portion is D, A / B is 1 or more and 1.6. In Ri, C / D is not less than 0.6, and wherein the (A / B) × (C / D) value F given by is 0.8 to 1.3.

  According to the present invention, the rate of change (A / B) of the distance between the heat shield and the melt surface of the silicon melt, which is the first parameter, and the rate of change (C / D) of the pulling speed, which is the second parameter. In addition, since the relationship (F), which is the third parameter, is set in the above range, the tail portion can be used even when a large-diameter crucible, for example, an inner diameter of 850 mm or more is used. It is possible to stably prevent the occurrence of precipitation and the deterioration of the quality of the straight body portion during the growth of the steel.

  In the present invention, the pulling device further includes a magnetic field applying means for applying a magnetic field to the silicon melt, and the tail portion is grown more than the magnetic field strength applied to the silicon melt when the straight body portion is grown. In some cases, it is preferable to weaken the magnetic field strength applied to the silicon melt. According to the present invention, since the convection of the silicon melt is increased at the time of growing the tail portion, a local low temperature region is hardly generated in the silicon melt, and the occurrence of precipitation is more effectively prevented.

  In this case, the magnetic field strength applied to the silicon melt at the time of growing the tail portion is 70% or less of the magnetic field strength applied to the silicon melt at the time of growing the straight body portion, and the tail It is preferable that the magnetic field strength applied to the silicon melt at the time of growing the part is 0.2 T or more. According to this, since the crystal growth rate does not change rapidly, it is not difficult to control the shape of the tail portion and the pulling rate.

  In the present invention, it is also preferable that C / D is more than 1. According to this, since the distance between the heat shield and the melt surface of the silicon melt can be increased to some extent when the tail portion is grown, there is a risk of contact between the heat shield and the silicon melt. It becomes possible to reduce.

  In the present invention, A / B is preferably 1.3 or less. According to this, it becomes possible to minimize the influence on the straight body portion at the time of growing the tail portion.

  In the present invention, at the time of growing the tail portion, it is preferable to increase the value of F as the remaining amount of the silicon melt decreases. When the remaining amount of the silicon melt is reduced, precipitation is likely to occur in the silicon melt, but according to the above method, it is possible to reliably prevent the occurrence of precipitation.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the silicon single crystal which can prevent generation | occurrence | production of precipitation at the time of the growth of a tail part stably can be provided, preventing the quality fall of a straight body part.

It is a schematic diagram which shows the structure of the pulling apparatus applicable to the manufacturing method of the silicon single crystal by preferable embodiment of this invention. 1 is a schematic cross-sectional view showing the structure of a silicon single crystal 20 pulled by a silicon single crystal pulling apparatus 10. 4 is a flowchart for explaining a method for manufacturing silicon single crystal 20. 4 is a graph showing the presence or absence of precipitation in each sample of Example 1. 3 is a graph showing the presence or absence of defect occurrence in each sample of Example 1. 6 is a graph showing the presence or absence of precipitation in each sample of Example 3. 6 is a graph showing the presence or absence of defect occurrence in each sample of Example 3. 6 is a graph showing the presence or absence of precipitation in each sample of Example 4.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing a configuration of a pulling apparatus applicable to a method for producing a silicon single crystal according to a preferred embodiment of the present invention.

  A silicon single crystal pulling apparatus 10 shown in FIG. 1 includes a chamber 11, a support rotary shaft 12 that passes through the center of the bottom of the chamber 11 and is provided in the vertical direction, and a graphite susceptor fixed to the upper end of the support rotary shaft 12. 13, a quartz crucible 14 accommodated in the graphite susceptor 13, a heater 15 provided around the graphite susceptor 13 for heating the silicon melt 21, and a support shaft drive mechanism for moving the support rotary shaft 12 up and down. 16, a seed chuck 17 for holding the seed crystal, a pulling wire 18 for suspending the seed chuck 17, a wire winding mechanism 19 for winding the wire 18, and the silicon single crystal 20 and the heater 15. The heat shield 22 provided and a control device 23 for controlling each part are provided. The heat shield 22 serves to prevent the silicon single crystal 20 from being heated by radiant heat from the heater 15 and the quartz crucible 14 and to suppress temperature fluctuations of the silicon melt 21.

  A gas inlet 24 for introducing Ar gas into the chamber 11 is provided in the upper part of the chamber 11. Ar gas is introduced into the chamber 11 from the gas introduction port 24 through the gas pipe 25, and the introduction amount is controlled by the conductance valve 26.

  A gas discharge port 27 for exhausting Ar gas in the chamber 11 is provided at the bottom of the chamber 11. Ar gas in the sealed chamber 11 is discharged to the outside from the gas discharge port 27 via the exhaust gas pipe 28. A conductance valve 29 and a vacuum pump 30 are provided in the middle of the exhaust gas pipe 28, and the pressure inside the chamber 11 is reduced by controlling the flow rate with the conductance valve 29 while sucking the Ar gas in the chamber 11 with the vacuum pump 30. The state is maintained.

  Further, a magnetic field applying means 31 is provided outside the chamber 11. The magnetic field applying means 31 plays a role of controlling convection by applying a magnetic field to the silicon melt 21. The magnetic field applied by the magnetic field applying means 31 may be a horizontal magnetic field or a cusp magnetic field.

  In the pulling of the silicon single crystal 20, the pulling speed of the silicon single crystal 20 and the temperature gradient between the silicon single crystal 20 and the silicon melt 21 are controlled with high accuracy under the control of the control device 23. The pulling speed of the silicon single crystal 20 is controlled mainly by the winding speed by the wire winding mechanism 19, and the temperature gradient is adjusted mainly by the output of the heater 15. As the pulling progresses, the silicon melt 21 in the quartz crucible 14 is reduced accordingly, and the molten metal surface 21a is lowered. The distances A and B between the hot water surface 21a and the heat shield 22 which are changed by this are adjusted by raising and lowering the support rotating shaft 12 by the support shaft driving mechanism 16. As will be described later, the distance A refers to the distance between the hot water surface 21a and the heat shield 22 during the growth of the straight body portion, and the distance B refers to the distance between the hot water surface 21a and the heat shield 22 during the growth of the tail portion. Refers to distance.

  FIG. 2 is a schematic cross-sectional view showing the structure of the silicon single crystal 20 pulled by the silicon single crystal pulling apparatus 10.

  As shown in FIG. 2, the silicon single crystal 20 has a shoulder portion 20a, a straight body portion 20b, and a tail portion 20c in order from the top along the growth direction A. The shoulder portion 20a is a portion whose diameter increases in the growth direction A, the straight body portion 20b is a portion whose diameter is constant in the growth direction A, and the tail portion 20c is a portion whose diameter decreases in the growth direction A. . As already described, only the straight body portion 20b is used as a product (silicon wafer), and the shoulder portion 20a and the tail portion 20c are not used as products. However, the shoulder portion is a portion necessary for expanding the diameter of the 20a silicon single crystal 20 to a desired diameter, and the tail portion 20c allows the silicon single crystal 20 to be melted into the silicon melt without causing dislocation in the straight body portion 20b. It is a part necessary for separating from 21.

  FIG. 3 is a flowchart for explaining a method of manufacturing the silicon single crystal 20.

  As shown in FIG. 3, in the growth of the silicon single crystal 20, seed drawing (formation of a neck portion) is first performed by a dash method in order to make the single crystal dislocation-free (step S1). Next, in order to obtain a single crystal having a required diameter, the shoulder portion 20a is grown (step S2), and when the diameter required by the single crystal is reached, the straight body portion 20b is grown with a constant diameter (step S3). After growing the straight body portion 20b to a predetermined length, tail restriction (formation of the tail portion 20c) is performed in order to separate the single crystal from the silicon melt without dislocation (step S4). Thereafter, the silicon single crystal 20 separated from the silicon melt is cooled under predetermined conditions, whereby an ingot of the silicon single crystal can be obtained.

  Each parameter in these steps is controlled by the control device 23 shown in FIG. Here, the distance between the heat shield 22 and the molten metal surface 21a when the straight body portion 20b is grown is A, and the distance between the thermal shield 22 and the molten metal surface 21a when the tail portion 20c is grown is B. When the pulling speed at the time of growing the portion 20b is C and the pulling speed at the time of growing the tail portion 20c is D, the control device 23 sets A / B to 1 to 1.6 and C / D is set to 0.6 or more and 1.4 or less. Furthermore, the value F given by (A / B) × (C / D) is set to 0.8 or more and 1.3 or less.

  The distance between the heat shield 22 and the molten metal surface 21 a has a great influence on the temperature gradient between the silicon single crystal 20 and the silicon melt 21. Specifically, when the distance between the heat shield 22 and the molten metal surface 21a is reduced, the radiant heat from the heater 15 and the quartz crucible 14 to the silicon single crystal 20 decreases, so that the heater 15 enters the silicon melt 21. It becomes necessary to control the amount of heat to increase, and as a result, the temperature gradient increases. On the contrary, if the distance between the heat shield 22 and the molten metal surface 21a is increased, the radiant heat from the heater 15 and the quartz crucible 14 to the silicon single crystal 20 increases, so the amount of heat input from the heater 15 to the silicon melt 21 is increased. It becomes necessary to control in the direction of decreasing, and as a result, the temperature gradient becomes smaller.

  When the temperature gradient is reduced, the temperature of the silicon melt 21 is lowered, and therefore, the temperature of the silicon melt 21 is locally lower than the melting point, so that precipitation (solidification) may occur. Such a problem is likely to occur at the time of growing the tail portion 20c where the remaining amount of the silicon melt 21 is reduced. Therefore, in order to prevent the precipitation of the silicon melt 21 at the time of growing the tail portion 20c, A ≧ B must be set. Since the distance A is determined so that the straight body portion 20b is grown with a desired quality, the distance B at the time of growing the tail portion 20c may be less than this. On the other hand, if the distance B is too small with respect to the distance A, the temperature history of the straight body 20b being cooled may be affected during the growth of the tail part 20c, and the quality of the straight body 20b may be deteriorated. is there. Considering this point, it is necessary to set A / B ≦ 1.6, and it is preferable to set A / B ≦ 1.3. Further, from the viewpoint of reliably preventing contact between the heat shield 22 and the silicon melt 21, the distance B is preferably set to 20 mm or more.

  On the other hand, the pulling speed has a great influence on the temperature gradient between the silicon single crystal 20 and the silicon melt 21. Specifically, in order to slow down the pulling speed, it is necessary to control the amount of heat input from the heater 15 to the silicon melt 21 so that the temperature gradient increases. On the contrary, in order to increase the pulling speed, it is necessary to control the amount of heat input from the heater 15 to the silicon melt 21, so that the temperature gradient becomes small.

  As described above, the occurrence of precipitation due to the decrease in the temperature gradient is likely to occur during the growth of the tail portion 20c where the remaining amount of the silicon melt 21 is reduced. Although it can be prevented, if the pulling speed D at the time of growing the tail portion 20c is too slow, not only the productivity is lowered, but also the quality of the straight body portion 20b may be affected. Considering this point, the relationship between the pulling speed C and the pulling speed D needs to be determined in relation to A / B. However, if C / D <0.6, it is difficult to reliably prevent the occurrence of precipitation no matter what value A / B is set. Therefore, C / D ≧ 0.6 is set. There is a need to. If C / D> 1.4, it is difficult to reliably prevent defects occurring in the straight body portion 20b regardless of what value A / B is set, so C / D ≦ 1. .4 must be set. Further, from the viewpoint of reliably preventing the occurrence of defects in the straight body portion 20b, the pulling speed D is preferably set to 0.3 mm / min or more.

  Thus, since the occurrence of precipitation is suppressed as the values of A / B and C / D are both large, in order to prevent the occurrence of precipitation while ensuring the quality of the straight body portion 20b, The value F given by (A / B) × (C / D) may be set within a predetermined range. Specifically, if F is set to 0.8 or more and 1.3 or less, it becomes possible to prevent the occurrence of precipitation while ensuring the quality of the straight body portion 20b. That is, when F <0.8, precipitation is likely to occur when the tail portion 20c is grown, and when F> 1.3, the straight body portion 20b is defective when the tail portion 20c is grown. Since it is likely to occur, it is necessary to set 0.8 ≦ F ≦ 1.3.

  The occurrence of precipitation becomes more prominent when the remaining amount of the silicon melt 21 decreases as the tail portion 20c grows. Therefore, in order to prevent precipitation until the tail portion 20c is completely grown, it is preferable to increase the value of F as the remaining amount of the silicon melt 21 decreases during the growth of the tail portion 20c.

  Furthermore, it is preferable to control the magnetic field application means 31 by the control device 23 so that the magnetic field strength at the time of growing the tail portion 20c is weaker than the magnetic field strength at the time of growing the straight body portion 20b. This is because, if the magnetic field strength is weakened, the convection of the silicon melt 21 increases, so that local low-temperature regions are less likely to occur in the silicon melt 21. In this case, the magnetic field strength at the time of growing the tail portion 20c is 70% or less with respect to the magnetic field strength at the time of growing the straight body portion 20b, and the magnetic field strength at the time of growing the tail portion 20c is 0.2T or more. It is preferable. According to this, since the crystal growth rate does not change rapidly, it is not difficult to control the shape of the tail portion 20c and the pulling rate.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. Needless to say, it is included in the range.

  Hereinafter, although the Example of this invention is described, this invention is not limited to this Example at all.

  Using a plurality of large-diameter quartz crucibles having an inner diameter of 850 mm to 950 mm, silicon single crystals each having a diameter of 315 mm in the straight body portion and a length of the straight body portion in the growth direction of 2400 mm were grown. The growth is performed under the condition that no defects such as OSF are generated in the straight body portion, the pulling speed during the growth of the straight body portion is controlled within the range of 0.25 to 0.45 mm / min, and the heat during the growth of the straight body portion is controlled. The distance between the shield and the melt surface of the silicon melt was controlled in the range of 60 to 90 mm.

  The control of the pulling speed and the control of the distance between the heat shield and the hot water surface were set so that the combination of the A / B value and the C / D value was different among the samples. The values of A / B, C / D, and F in each sample are as shown in Table 1. The magnetic field strength was fixed at 0.3T.

  During pulling up of these samples, a part of the molten metal surface was deposited during the growth of the tail portion of samples 20 to 26, and dislocations generated thereby propagated to the straight barrel portion. As shown in Table 1, these samples 20 to 26 all had F <0.8. In the other samples 1 to 19, no precipitation occurred when the tail portion was grown.

  Next, silicon wafers were respectively cut out from the straight body portions of Samples 1 to 19 pulled up without causing precipitation, and the presence or absence of defects such as OSF was evaluated by an X-ray topograph method. When evaluating defects, each silicon wafer was immersed in an aqueous copper sulfate solution, dried, heated in a nitrogen atmosphere at 900 ° C. for 20 minutes, cooled, immersed in a hydrofluoric acid-nitric acid mixture, and the surface Cu-silicide. This was done after removing the layer and etching away. As a result, each sample had a defect in Samples 1 to 8, although it was pulled up under the condition that no defect such as OSF occurred in the straight body portion. The samples 20 to 26 having dislocations were not evaluated for defects.

  4 and 5 are graphs in which the relationship between A / B and C / D in each sample is plotted. FIG. 4 shows the presence or absence of precipitation, and FIG. 5 shows the presence or absence of defects.

  As shown in FIG. 4, the presence or absence of precipitation is bounded by F = 0.8, and precipitation occurs when F <0.8, whereas precipitation does not occur when F ≧ 0.8. found. On the other hand, as shown in FIG. 5, the presence or absence of a defect occurs when F = 0.8 and F = 1.3 as boundaries, and a defect occurs when F <0.8 or F> 1.3. When 0.8 ≦ F ≦ 1.3, it was found that no defect occurred.

  Using a quartz crucible with an inner diameter of 850 mm, a silicon single crystal with a diameter of 315 mm in the straight body part and a length of the straight body part in the growth direction of 2400 mm is pulled up at a speed of 0.5 mm / min, a heat shield and silicon The distance from the molten metal surface was fixed to 70 mm, the magnetic field strength at the time of growing the straight body portion was fixed at 0.3 T, and the magnetic field strength at the time of growing the tail portion was changed variously. The magnetic field strength at the time of growing the tail portion was set as shown in Table 2 by the ratio of the magnetic field strength at the time of growing the straight body portion. Then, how much the change in the pulling speed by the automatic control occurs in each sample was evaluated. In Table 2, “O” indicates that the 10-minute average pulling speed change is less than 20% within 60 minutes, and “X” indicates that the 10-minute average pulling is within 60 minutes. The case where the speed change is 20% or more is shown.

  As a result, as shown in Table 2, in samples 27 to 29 having a magnetic field strength ratio of 0.7 to 1.0, the speed change was less than 20%, whereas the magnetic field strength ratio was 0.6. In sample 30, a speed change of 20% or more occurred. A large speed change is thought to occur because natural convection predominates due to a decrease in magnetic field strength. When a speed change of 20% or more occurs, shape control and speed control become difficult, and the silicon single crystal from the melt becomes difficult. Problems arise, such as dislocations and the inability to control the thermal history when disconnecting. In order to prevent such a problem, as shown in Table 2, the magnetic field strength ratio may be set to 0.7 or more.

  A plurality of silicon single crystals were grown under the same conditions as in Example 1 except that no magnetic field was applied to the silicon melt when growing the tail portion. And like Example 1, the presence or absence of precipitation and the presence or absence of defect generation were evaluated. The result of evaluating the presence or absence of precipitation is shown in FIG. 6, and the result of evaluating the presence or absence of the occurrence of defects is shown in FIG.

  As shown in FIG. 6, the presence or absence of precipitation was at a boundary of F = 0.65, and precipitation was less likely to occur than in Example 1. However, as shown in FIG. 7, F = 0.95 and F = 1.2 are the boundaries for the presence or absence of defects, and the range of F values where defects do not occur is narrower than in Example 1 (0. 95 ≦ F ≦ 1.2). As a result, it was found that when a magnetic field is not applied during tail portion growth, precipitation is suppressed, but the control margin is narrowed due to the influence of thermal history.

  Using a quartz crucible with an inner diameter of 760 mm, silicon single crystals each having a diameter of 315 mm in the straight body portion and a length in the growth direction of 2400 mm were grown. The growth is performed under the condition that no defects such as OSF are generated in the straight body part, the pulling speed at the time of growing the straight body part is 0.4 mm / min, and the distance between the heat shield and the molten metal surface at the time of growing the straight body part Was controlled in the range of 80 mm.

  About the combination of the value of A / B and the value of C / D, it set so that it might differ between each sample. The magnetic field strength was fixed at 0.3T. And like Example 1, the presence or absence of precipitation was evaluated. The result of evaluating the presence or absence of precipitation is shown in FIG.

  As shown in FIG. 8, F = 0.65 was a boundary in the presence or absence of precipitation, and precipitation was less likely to occur than in Example 1. Thus, it was found that when a large-diameter quartz crucible having an inner diameter of 850 mm or more as in Example 1 is used, the control margin is narrowed.

DESCRIPTION OF SYMBOLS 10 Silicon single crystal pulling apparatus 11 Chamber 12 Support rotating shaft 13 Graphite susceptor 15 Heater 16 Support shaft drive mechanism 17 Seed chuck 18 Wire 19 Wire winding mechanism 20 Silicon single crystal 20a Shoulder portion 20b Straight body portion 20c Tail portion 21 Silicon melt 21a Hot water surface 22 Heat shield 23 Control device 24 Gas inlet 25 Gas pipe 26 Conductance valve 27 Gas outlet 28 Exhaust pipe 29 Conductance valve 30 Vacuum pump 31 Magnetic field applying means

Claims (7)

By pulling up the seed crystal immersed in the silicon melt in the crucible, a shoulder portion whose diameter increases in the growth direction, a straight body portion whose diameter is constant in the growth direction, and a tail portion whose diameter decreases in the growth direction A method for producing a silicon single crystal having
Using a pulling device having a heater for heating the silicon melt, and a heat shield provided between the silicon single crystal and the heater,
A distance between the thermal shield and the silicon melt surface during the growth of the straight body portion is A, and a distance between the thermal shield and the silicon melt surface during the tail portion growth. B, when the lifting speed when growing the straight body portion is C, and when the lifting speed when growing the tail portion is D,
A / B is 1 or more and 1.6 or less, C / D is 0.6 or more, and the value F given by (A / B) × (C / D) is 0.8 or more and 1.3 or less. There is provided a method for producing a silicon single crystal. The pulling device further has a magnetic field applying means for applying a magnetic field to the silicon melt,
The magnetic field strength applied to the silicon melt at the time of growing the tail portion is made weaker than the magnetic field strength applied to the silicon melt at the time of growing the straight body portion. A method for producing a silicon single crystal.   The magnetic field strength applied to the silicon melt at the time of growing the tail portion is 70% or less of the magnetic field strength applied to the silicon melt at the time of growing the straight body portion, and the tail portion is grown. 3. The method for producing a silicon single crystal according to claim 2, wherein the magnetic field strength applied to the silicon melt is 0.2 T or more.   C / D is more than one, The manufacturing method of the silicon single crystal as described in any one of Claim 1 thru | or 3 characterized by the above-mentioned.   A / B is 1.3 or less, The manufacturing method of the silicon single crystal as described in any one of Claims 1 thru | or 4 characterized by the above-mentioned.   6. The method for producing a silicon single crystal according to claim 1, wherein, when the tail portion is grown, the value of F is increased as the remaining amount of the silicon melt decreases. 6.   The method for producing a silicon single crystal according to any one of claims 1 to 6, wherein an inner diameter of the crucible is 850 mm or more.

Images