Crucible-supporting pedestal, quartz crucible-supporting device, and method for producing silicon single crystal

Abstract

A crucible-supporting pedestal includes a fitting recess portion into which a divided graphite member is fittable. An opening edge of the fitting recess portion is formed such that a contact area between the opening edge and the divided graphite member is provided at a position higher than a surface of a solidified product of a silicon melt which remains in a quartz crucible after a silicon single crystal is grown, and a force, which is applied to the divided graphite member by an expansion of the silicon melt when the silicon melt is solidified, is applied to a position lower than the contact area.

Claims

1. A crucible-supporting pedestal that is attachable to a single crystal pulling-up apparatus for growing a single crystal from a silicon melt using a Czochralski process, and supports a plurality of divided graphite members which are obtained by vertically dividing a graphite crucible which supports a quartz crucible, the quartz crucible having a level at which level remaining silicon melt is solidified following operation, the crucible-supporting pedestal comprising: a fitting recess portion into which the plurality of divided graphite members are fittable, wherein an opening edge of the fitting recess portion is formed such that a contact area between the opening edge and the plurality of divided graphite members is provided at a position higher than the level at which level remaining silicon melt is solidified such that a force, which is applied to the plurality of divided graphite members by an expansion of remaining silicon melt in the case that the silicon melt is solidified, is applied to a position lower than the contact area.

2. The crucible-supporting pedestal according to claim 1, wherein in a case that a depth of the fitting recess portion is A (mm), a thickness at a position in the plurality of divided graphite members which corresponds to a center of a bottom portion of the graphite crucible is B (mm), a thickness at a center of a bottom portion in the quartz crucible is C (mm), and a height above the center of the bottom portion in the quartz crucible of the level at which level remaining silicon melt is solidified is D (mm), the fitting recess portion is formed to satisfy the following inequality (1):
A>B+C+D  (1).

3. A quartz crucible-supporting device comprising: the crucible-supporting pedestal according to claim 2 which supports the plurality of divided graphite members, and the plurality of divided graphite members which are obtained by vertically dividing the graphite crucible which supports the quartz crucible; wherein an inner diameter of the graphite crucible before the graphite crucible is vertically divided is from 452 mm to 462 mm, and wherein the B is from 12 mm to 20 mm, the C is from 6 mm to 15 mm, and the D is from 10 mm to 30 mm.

4. A quartz crucible-supporting device comprising: the crucible-supporting pedestal according to claim 2 which supports the plurality of divided graphite members, and the plurality of divided graphite members which are obtained by vertically dividing the graphite crucible which supports the quartz crucible; wherein an inner diameter of the graphite crucible before the graphite crucible is vertically divided is from 553 mm to 615 mm, and wherein the B is from 15 mm to 35 mm, the C is from 8 mm to 22 mm, and the D is from 15 mm to 40 mm.

5. A quartz crucible-supporting device comprising: the crucible-supporting pedestal according to claim 2 which supports the plurality of divided graphite members, and the plurality of divided graphite members which are obtained by vertically dividing the graphite crucible which supports the quartz crucible; wherein an inner diameter of the graphite crucible before the graphite crucible is vertically divided is from 803 mm to 823 mm, and wherein the B is from 20 mm to 45 mm, the C is from 10 mm to 25 mm, and the D is from 15 mm to 40 mm.

6. A quartz crucible-supporting device comprising: the crucible-supporting pedestal according to claim 2 which supports the plurality of divided graphite members, and the plurality of divided graphite members which are obtained by vertically dividing the graphite crucible which supports the quartz crucible; wherein an inner diameter of the graphite crucible before the graphite crucible is vertically divided is from 1,001 mm to 1,031 mm, and wherein the B is from 25 mm to 55 mm, the C is from 15 mm to 30 mm, and the D is from 20 mm to 80 mm.

7. The crucible-supporting pedestal according to claim 1, wherein in a case that depth of the fitting recess portion is A (mm), and a thickness at a position in the plurality of divided graphite members which corresponds to a center of a bottom portion of the graphite crucible is B (mm), the fitting recess portion is formed to satisfy the following equation (2):
A>B+45 mm  (2).

8. A quartz crucible-supporting device comprising: the crucible-supporting pedestal according to claim 7 which supports the plurality of divided graphite members, and the plurality of divided graphite members which are obtained by vertically dividing the graphite crucible which supports the quartz crucible; wherein an inner diameter of the graphite crucible before the graphite crucible is vertically divided is from 452 mm to 462 mm, and wherein the B is from 12 mm to 20 mm.

9. The crucible-supporting pedestal according to claim 1, wherein in a case that depth of the fitting recess portion is A (mm), and a thickness at a position in the plurality of divided graphite members which corresponds to a center of a bottom portion of the graphite crucible is B (mm), the fitting recess portion is formed to satisfy the following equation (3):
A>B+62 mm  (3).

10. A quartz crucible-supporting device comprising: the crucible-supporting pedestal according to claim 4 which supports the plurality of divided graphite members, and the plurality of divided graphite members which are obtained by vertically dividing the graphite crucible which supports the quartz crucible; wherein an inner diameter of the graphite crucible before the graphite crucible is vertically divided is from 553 mm to 615 mm, and wherein the B is from 15 mm to 35 mm.

11. The crucible-supporting pedestal according to claim 1, wherein in a case that depth of the fitting recess portion is A (mm), and a thickness at a position in the plurality of divided graphite members which corresponds to a center of a bottom portion of the graphite crucible is B (mm), the fitting recess portion is formed to satisfy the following equation (4):
A>B+65 mm  (4).

12. A quartz crucible-supporting device comprising: the crucible-supporting pedestal according to claim 5 which supports the plurality of divided graphite members, and the plurality of divided graphite members which are obtained by vertically dividing the graphite crucible which supports the quartz crucible; wherein an inner diameter of the graphite crucible before the graphite crucible is vertically divided is from 803 mm to 823 mm, and wherein the B is from 20 mm to 45 mm.

13. The crucible-supporting pedestal according to claim 1, wherein in a case that depth of the fitting recess portion is A (mm), and a thickness at a position in the plurality of divided graphite members which corresponds to a center of a bottom portion of the graphite crucible is B (mm), the fitting recess portion is formed to satisfy the following equation (5):
A>B+110 mm  (5).

14. A quartz crucible-supporting device comprising: the crucible-supporting pedestal according to claim 6 which supports the plurality of divided graphite members, and the plurality of divided graphite members which are obtained by vertically dividing the graphite crucible which supports the quartz crucible; wherein an inner diameter of the graphite crucible before the graphite crucible is vertically divided is from 1,001 mm to 1,031 mm, and wherein the B is from 25 mm to 55 mm.

15. A quartz crucible-supporting device comprising: the crucible-supporting pedestal according to claim 1 which supports the plurality of divided graphite members, and the plurality of divided graphite members which are obtained by vertically dividing the graphite crucible which supports the quartz crucible.

16. A method for producing a silicon single crystal that uses the quartz crucible and the quartz crucible-supporting device according to claim 15 which supports the quartz crucible, wherein the silicon melt is solidified such that a surface of the solidified product of the silicon melt which remains in the quartz crucible after the silicon single crystal is grown is positioned lower than the contact area between the opening edge of the fitting recess portion and the plurality of divided graphite members.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1A is a plan view of a quartz crucible-supporting device in an embodiment of the present invention;

(2) FIG. 1B is a cross-sectional view showing the quartz crucible-supporting device the embodiment, which is taken along a line B-B in FIG. 1A;

(3) FIG. 1C is a partial cross-sectional view of the quartz crucible-supporting device in the embodiment;

(4) FIG. 2 is a view describing the action of the quartz crucible-supporting device in the embodiment;

(5) FIG. 3 is a schematic view showing the configuration of a single crystal pulling-up apparatus in the embodiment;

(6) FIG. 4A is a plan view of a quartz crucible-supporting device in the related art;

(7) FIG. 4B is a cross-sectional view showing the quartz crucible-supporting device in the related art, which is taken along the line B-B in FIG. 4A;

(8) FIG. 4C is a partial cross-sectional view of the quartz crucible-supporting device in the related art;

(9) FIG. 5A is a view describing the action of the quartz crucible-supporting device in the related art; and

(10) FIG. 5B is a view describing the action of the quartz crucible-supporting device in the related art.

DESCRIPTION OF THE EMBODIMENTS

Embodiment

(11) Hereinbelow, an embodiment of the present invention will be described with reference to the drawings.

(12) [Configuration of Quartz Crucible-Supporting Device]

(13) As shown in FIGS. 1A and 1B, a quartz crucible-supporting device 10 supports a quartz crucible 221. The quartz crucible-supporting device 10 includes a first divided graphite member 11A, a second divided graphite member 11B, and a third divided graphite member 11C (hereinafter, may be collectively referred to a a “divided graphite member 11”) which are obtained by vertically dividing a graphite crucible into three equal parts; a crucible-supporting pedestal 12 that supports the divided graphite member 11; and a separation prevention member 93 that prevents the divided graphite members 11A, 11B, and 11C from moving in a direction where the divided graphite members 11A, 11E, and 11C move away from a center CA of the quartz crucible 221 and separate from each other.

(14) A pin support hole ill into which a pin portion 93B of the separation prevention member 93 is inserted is provided in an upper surface of the divided graphite member 11. The pin support hole 111 is formed such that when the pin portion 93B is inserted into the pin support hole 111, a gap is provided between the pin support hole 111 and the pin portion 93B.

(15) The crucible-supporting pedestal 12 is made or graphite, and is formed into a circle shape in a plan view. A support shaft fitting groove 121 into which a support shaft. 25 is fitted is provided in one surface of the crucible-supporting pedestal 12.

(16) A fitting recess portion 122 into which a lower portion of the divided graphite member 11 is fittable is provided in the other surface of the crucible-supporting pedestal 12. As shown in FIG. 2, when the depth of the fitting recess portion 122 (the distance from an opening plane 124 of the fitting recess portion 122 to the center of a bottom portion of the fitting recess portion 122) is A (mm), the thickness of the divided graphite member 11 at a position which corresponds to the center of a bottom portion of the graphite crucible before the graphite crucible is divided is B (mm), the thickness at the center of a bottom portion in the quartz crucible 221 is C (mm), the height of a solidified product M1 of a silicon melt M which remains in the quartz crucible 221 after a silicon single crystal is grown (the distance from the surface of the solidified product M1 to the center of the bottom portion of the quartz crucible 221) is D (mm) (hereinafter, referred to as a “height D of the solidified product), an opening edge 123 of the fitting recess portion 122 is formed to satisfy the following inequality (1).

(17) It is preferable that an upper limit value of the depth A of the fitting recess portion 122 is set at a value where the opening edge 123 is positioned at the same height as that of an upper end of the divided graphite member 11 or is positioned lower than the upper end.
A>B+C+D  (1)

(18) With this configuration satisfying the inequality (1), a contact area P1 between the opening edge 123 of the fitting recess portion 122 and the divided graphite members 11A, 11B, and 11C is positioned higher than the surface of the solidified product M1 of the silicon melt M after the silicon single crystal is grown.

(19) In the case of growing a silicon single crystal which has a predetermined value of diameter after grinding an outer periphery of the silicon single crystal, it is preferable that the inner diameter of the graphite crucible before the graphite crucible is divided, the thickness B of the graphite crucible at the center of the bottom portion, the thickness C of the quartz crucible 221 at the center of the bottom portion, and the height D of the solidified product of the silicon melt are within the ranges shown in the following Table 1.

(20) In the case where the diameter of the silicon single crystal is 150 mm, the crucible-supporting pedestal 12 may be formed to satisfy the following inequality (2), in the case where the diameter of the silicon single crystal is 200 mm, the crucible-supporting pedestal 12 may be formed to satisfy the following inequality (3), in the case where the diameter of the silicon single crystal is 300 mm, the crucible-supporting pedestal 12 may be formed to satisfy the following inequality (4), and in the case where the diameter of the silicon single crystal is 450 mm, the crucible-supporting pedestal 12 may be formed to satisfy the following inequality (5).
A>B+45 mm  (2)
A>B+62 mm  (3)
A>B+65 mm  (4)
A>B+110 mm  (5)

(21) The inner diameters of the graphite crucible shown in Table 1 are the maximum inner diameters of the graphite crucible, and in the case where the graphite crucible includes a straight barrel portion (cylindrical portion with the same inner diameter at all positions in a height direction), the inner diameters are the inner diameters of the straight barrel portion.

(22) The remaining amount of the silicon melt M after the silicon single crystal is grown is from 1% to 10% of the initial charge amount of a raw silicon material. The heights D of the solidified product shown in Table 1 are values when the silicon melts M which are equivalent to 1% to 10% of the initial charge amount are solidified.

(23) TABLE-US-00001 TABLE 1 Thickness B Thickness C Height D of Diameter of at center of at center of solidified silicon single Inner diameter of bottom portion in bottom portion in product of crystal (mm) graphite crucible graphite crucible quartz crucible silicon melt 150 mm From 452 mm to From 12 mm to From 6 mm to From 10 mm to 462 mm 20 mm 15 mm 30 mm (approximately 18 inch) 200 mm From 553 mm to From 15 mm to From 8 mm to From 15 mm to 615 mm (from 35 mm 22 mm 40 mm approximately 22 inch to approximately 24 inch) 300 mm From 803 mm to From 20 mm to From 10 mm to From 15 mm to 823 mm 45 mm 25 mm 40 mm (approximately 32 inch) 450 mm From 1,001 mm From 25 mm to From 15 mm to From 20 mm to to 1,031 mm 55 mm 30 mm 80 mm (approximately 40 inch)
[Method for Producing Silicon Single Crystal]

(24) A method for producing a silicon single crystal by the Czochralski process using the quartz crucible-supporting device 10 will be described.

(25) As shown in FIG. 3, the quartz crucible 221 is supported on the quartz crucible-supporting device 10 in a chamber 21 of a single crystal pulling-up apparatus 1 (hereinafter, the quartz crucible 221 and the quartz crucible-supporting device 10 may be collectively referred as a “crucible 22”), and the quartz crucible 221 is charged with a raw silicon solid material. The raw silicon material in the crucible 22 is melted to produce the silicon melt M by heating the crucible 22 with a heater 23.

(26) In the case where the silicon melt M is produced, the quartz crucible 221, the divided graphite member 11, and the crucible-supporting pedestal 12 expand due to the heating. The divided graphite members 11A, 11B, and 11C are pushed outward by the quartz crucible 221 which is expanded, and until the pin portions 93B of the separation Prevention members 93 relatively move in the pin support holes 111 to come into contact with the pin support holes 111, the divided graphite members 11A, 11B, and 11C separate from each other.

(27) After the silicon melt M is produced, the chamber 21 is maintained in an inert atmosphere under reduced pressure by introducing an argon gas into the chamber 21, and after while the crucible 22 is rotated by driving the support shaft 25, a seed crystal SC is brought into contact with the silicon melt M, a silicon single crystal SM is grown by pulling up the seed crystal SC with a pulling-up cable 24.

(28) After the silicon single crystal SM is grown, in order to exchange the quartz crucible 221, the remainder of the silicon melt M is solidified by cooling the inside of the chamber 21.

(29) At the time, as described above, the silicon melt M is solidified in the state of being more expanded than when the silicon melt M is melted.

(30) On the other hand, the quartz crucible 221 shrinks to return to the shape before the expansion; however, since the quartz crucible 221 accommodates the solidified product M1 which is more expanded than when the solidified product M1 is melted, at least an accommodating part of the quartz crucible 221 which accommodates the solidified product M1 cannot return to the state before the expansion.

(31) Since there is no obstacle to the shrinkage of the crucible-supporting pedestal 12, the crucible-supporting pedestal 12 is capable of returning to the shape before the expansion.

(32) However, since the accommodating part of the quartz crucible 221 which accommodates the solidified product M1 cannot return to the state before the expansion, as shown in FIG. 2, when the divided graphite members 11A, 11B, and 11C shrink, a force F1 is applied outward to a part of each of the divided graphite members 11A, 11B, and 11C which is in contact with the accommodating part. At the time, since the contact area P1 is positioned higher than the surface of the solidified product M1 of the silicon melt M, a momentum E1 is produced by the force F1 to rotate upper ends of the divided graphite members 11A, 11B, and 11C around the contact area P1, which is the center of rotation, in a direction where the upper ends approach each other. Due to the momentum E1, upper end sides of the divided graphite members 11A, 11B, and 11C are prevented from being open; and thereby, it is possible to prevent the divided graphite members 11A, 11B, and 11C from causing damage to the heater 23.

Modification Example

(33) The present invention is not limited to only the above-described embodiment, and various improvements, design changes, or the like can be made to the present invention without departing from the concept of the present invention.

(34) For example, a divided support member may have a shape which is obtained by vertically dividing the graphite crucible into two equal parts or four equal parts.