JP3428625B2 - Apparatus and method for pulling silicon single crystal - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon single crystal pulling apparatus for pulling and growing a silicon single crystal rod and a pulling method thereof.

[0002]

2. Description of the Related Art Conventionally, as a silicon single crystal pulling apparatus of this type, a quartz crucible 4 in which a silicon melt 2 is stored is housed in a chamber 3 as shown in FIG. There is disclosed a pulling device (Japanese Patent Publication No. 57-40119) in which a heat shield member 7 is inserted so as to surround the silicon single crystal ingot 1 between the quartz crucible 4 and the inner surface of the quartz crucible 4. In this apparatus, a cone portion 7a having a diameter that decreases as the heat shield member 7 moves downward, and an outer peripheral edge connected to a lower edge of the cone portion 7a and extending horizontally and an inner peripheral edge near the outer peripheral surface of the silicon single crystal ingot 1. And a flange portion 7c whose inner peripheral edge is connected to the upper edge of the cone portion 7a and extends horizontally and whose outer peripheral edge reaches the upper surface of the heat insulating cylinder 8. The heat shield member 7 is fixed by placing the flange portion 7c on the upper surface of the heat insulating cylinder 8. Reference numeral 9 in FIG. 4 is a heater.

In the pulling apparatus thus constructed, when the silicon single crystal ingot 1 is pulled up from the silicon melt 2, the liquid surface of the silicon melt 2 is gradually lowered and the inner peripheral wall of the quartz crucible 4 is exposed. Although the radiant heat from the exposed inner peripheral wall of the quartz crucible 4 is directed to the outer peripheral surface of the silicon single crystal rod 1, this radiant heat is blocked by the heat shield member 7 and does not reach the outer peripheral surface of the silicon single crystal rod 1. As a result, the solidification of the silicon single crystal ingot 1 during pulling is not delayed, and the silicon single crystal ingot 1 is quickly cooled.

[0004]

However, in the conventional pulling apparatus disclosed in Japanese Patent Publication No. 57-40119, a high temperature silicon melt is formed near the solid-liquid interface of the silicon single crystal rod pulled from the silicon melt. Since the radiant heat from the liquid is shielded by the heat shield member, the amount of heat radiated from the outer peripheral surface of the silicon single crystal rod is relatively large. As a result, the temperature distribution inside the silicon single crystal rod gradually decreases from the center toward the outer peripheral surface, and the solid-liquid interface, which was almost flat when the shoulder portion of the silicon single crystal rod was formed, is increased as the silicon single crystal rod is pulled up. When the straight body portion was formed, it changed so as to curve upward, and there was a risk that thermal stress would occur in the silicon single crystal rod. Further, when pulling a plurality of types of silicon single crystal rods having different straight body diameters by the same device, the heat shield member suitable for the straight body diameters of the silicon single crystal rods to be pulled has a straight body diameter It is also necessary to avoid the inconvenience of replacing different silicon single crystal ingots every time they are pulled.

An object of the present invention is to make it possible to reduce the occurrence of thermal stress in the silicon single crystal rod by making the solid-liquid interface shape of the silicon single crystal rod pulled from the silicon melt uniform. And to provide a method of raising the price. Another object of the present invention is to
It is an object of the present invention to provide a silicon single crystal pulling apparatus and a pulling method thereof that can pull a plurality of types of silicon single crystal rods having different straight body diameters without replacing the heat shield member.

[0006]

The invention according to claim 1 is
As shown in FIG. 1, a quartz crucible 13 provided in a chamber 11 in which a silicon melt 12 is stored, and a quartz crucible 1
The heater 18 that surrounds the outer peripheral surface of the silicon melt 3 and heats the silicon melt 12, and the outer peripheral surface of the silicon single crystal rod 25 pulled up from the silicon melt 12 and the lower end of the silicon melt 1
The present invention is an improvement of a silicon single crystal pulling apparatus provided with a heat shield member 26 which is configured to be positioned above and spaced apart from two surfaces and which shields radiant heat from the heater 18. The characteristic structure is that a cone-shaped heat dissipation suppressing portion 26c inclined downward so that the opening diameter becomes smaller as it goes downward is formed in the lower portion of the heat shield member 26, and the plurality of heat radiators 27 are made of silicon single crystal rods. The heat radiation suppressing portion 26c so as to surround 25
A plurality of heat radiators 27 are arranged so as to be radially movable above.
Is provided with the heat radiator moving means 41 for changing the distances of the plurality of heat radiators 27 to the peripheral surface of the silicon single crystal rod 25.

In the apparatus for pulling a silicon single crystal according to the present invention, the temperature of the plurality of heat radiators 27 arranged on the heat radiation suppressing portion 26c rises due to the radiant heat from the high temperature silicon melt 12. Or silicon melt 12
The radiant heat from or the heat radiated from the silicon single crystal rod 25 is reflected by the thermal radiator 27. By moving each of the plurality of heat radiators 27 to the vicinity of the silicon single crystal rod 25, the silicon single crystal rod 2 in the vicinity of the silicon melt 12 is moved.
Rapid heat dissipation from the outer peripheral surface of 5 is suppressed. As a result,
Abrupt temperature decrease of the outer peripheral portion of the silicon single crystal ingot 25 is prevented to make the solid-liquid interface shape substantially flat. In addition, this claim 1
In the apparatus for pulling a silicon single crystal described in (1), even when pulling a plurality of types of silicon single crystal rods 25 having different straight body diameters, the plurality of thermal radiators 27 are moved and the plurality of thermal radiators are moved. By changing the diameter of the opening surrounded by the body 27, the silicon single crystal ingot 2 to be pulled up is changed.
A plurality of heat radiating bodies 27 are arranged in accordance with the straight body diameter of 5. As a result, it is possible to use the same heat shield member 26 and avoid the trouble of replacing the heat shield member each time the silicon single crystal ingots 25 having different straight body diameters are pulled.

The invention according to claim 2 is the invention according to claim 1, wherein the heat radiation member moving means 41 is a drive gear provided on the upper part of the chamber 11 and a drive gear provided on the upper part of the chamber 11. A drive motor 46 for driving the motor, and a support rod 42 around which a rack gear that is suspended from the upper portion of the chamber 11 and meshes with the drive gear is formed.
And a connecting wire 44 that connects the lower end of the support rod 42 and the heat radiator 27 to each other. In the apparatus for pulling a silicon single crystal according to the second aspect, the support rod 42 moves up and down by the rotation of the drive gear that meshes with the rack gear, so that the heat radiation body 27 can be easily moved.

According to a third aspect of the present invention, a silicon single crystal rod 25 growing from the silicon melt 12 stored in the quartz crucible 13 is formed into a cylindrical heat shield member 26 and a downward face formed below the heat shield member 26. It is surrounded by a cone-shaped heat dissipation suppressing portion 26c inclined to the outside, and a plurality of thermal radiators 27 are radially movably arranged so as to surround the silicon single crystal rod 25 on the heat dissipation suppressing portion 26c. Is the method of pulling up. The characteristic point is that the silicon single crystal rod 2
5 is moved to a position separated from the shoulder portion 25b on the heat dissipation suppressing portion 26c when the shoulder portion 25b of 5 is formed, and the plurality of heat radiator 27 is moved when the straight body portion 25c of the silicon single crystal rod 25 is formed. It is located near the straight body portion 25c.

In the method of pulling up the silicon single crystal according to the third aspect of the present invention, the heat of the silicon melt 12 is increased by moving the plurality of heat radiating bodies 27 to the positions apart from the shoulder portion 25b when the shoulder portion 25b is formed. Is actively dissipated to the shoulder portion 25b in the process of forming, and the shoulder portion 25b is quickly formed. On the other hand, when the straight body portion 25c is formed, a plurality of heat radiators 27 are moved to the vicinity of the straight body portion 25c to suppress rapid heat dissipation from the outer peripheral surface of the silicon single crystal rod 25 in the vicinity of the silicon melt 12, and the silicon single crystal is formed. The solid-liquid interface shape is made substantially flat by preventing a sharp temperature decrease in the outer peripheral portion of the rod 25.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, a quartz crucible 13 for storing a silicon melt 12 is provided in a chamber 11 of a silicon single crystal pulling apparatus 10, and an outer surface of the quartz crucible 13 is covered with a graphite susceptor 14. To be done. The lower surface of the quartz crucible 13 is the above graphite susceptor 14.
It is fixed to the upper end of the support shaft 16 via, and the lower part of the support shaft 16 is connected to the crucible drive means 17. Although not shown, the crucible driving means 17 has a first rotation motor for rotating the quartz crucible 13 and an elevating motor for elevating the quartz crucible 13, and these motors can rotate the quartz crucible 13 in a predetermined direction. At the same time, it can move vertically. The outer peripheral surface of the quartz crucible 13 is a quartz crucible 13.
A heater 18 surrounds the heater 18 at a predetermined distance from the heater 18. Heater 1
Numeral 8 heats and melts the high-purity silicon polycrystalline material charged into the quartz crucible 13 to form a silicon melt.

A cylindrical casing 21 is connected to the upper end of the chamber 11. The casing 21 is provided with pulling up means 22. The pulling means 22 is a pulling head (not shown) provided on the upper end of the casing 21 so as to be horizontally rotatable, a second rotation motor (not shown) for rotating the head, and a quartz crucible 13 from the head.
A wire cable 23 hanging toward the center of rotation of
A pulling motor (not shown) provided in the head for winding or unwinding the wire cable 23. A seed crystal 24 for dipping in the silicon melt 12 and pulling up the silicon single crystal ingot 25 is attached to the lower end of the wire cable 23.

A heat shield member 26 surrounding the outer peripheral surface of the silicon single crystal rod 25 is provided between the outer peripheral surface of the silicon single crystal rod 25 and the inner peripheral surface of the quartz crucible 13. The heat shield member 26 has a cylindrical portion 26a which is formed in a cylindrical shape and shields the radiant heat from the heater 18, and a flange portion 26b which is connected to the upper edge of the cylindrical portion 26a and projects outward in a substantially horizontal direction. By placing the flange portion 26b on the heat insulating cylinder 19, the heat shield member 2 is arranged so that the lower edge of the cylinder portion 26a is located above the surface of the silicon melt 12 by a predetermined distance.
6 is fixed in the chamber 11.

Further, the chamber 11 includes the chamber 11
A gas supply / discharge means 28 for supplying an inert gas to the silicon single crystal rod side and discharging the inert gas from the inner peripheral surface side of the crucible of the chamber 11 is connected. The gas supply / discharge means 28 has one end connected to the peripheral wall of the casing 21 and the other end connected to a supply pipe 29 connected to a tank (not shown) for storing the inert gas, and one end connected to the lower wall of the chamber 11. Discharge pipe 30 whose other end is connected to a vacuum pump (not shown)
Have and. The supply pipe 29 and the discharge pipe 30 are provided with first and second flow rate adjusting valves 31, 32 for adjusting the flow rates of the inert gas flowing through these pipes 29, 30, respectively.

At the lower part of the cylindrical portion 26a which is the heat shield member 26, there is formed a cone-shaped heat radiation suppressing portion 26c which is inclined downward so that the opening diameter becomes smaller as it goes downward, and a plurality of heat radiation suppressing portions 26c are provided. A heat radiation body 27 is arranged so as to surround the silicon single crystal ingot 25 and can be moved radially. As shown in FIG. 3 and FIG. 4, six heat radiators 27 in this embodiment are used, and the silicon single crystal rod 2 is used.
5 (FIG. 1) as a center and arranged at an equal angle. Each heat radiating body 27 is made of carbon, and a roller 27a is provided at the bottom thereof. Recessed grooves 26d having a width into which the rollers 27a can be inserted are radially formed on the upper surface of the heat dissipation suppressing portion 26c. By inserting the rollers 27a into the recessed grooves 26d, the six heat radiators 27 are respectively radially formed. It is movably arranged.

In addition, a plurality of through holes 27c are provided in the plurality of heat radiating members 27 from the lower part to the upper part in order to allow the inert gas supplied by the gas supply / discharge means 28 (FIGS. 1 and 2) to flow. Connecting wires 44 of the heat radiation body moving means 41 (FIGS. 1 and 2) which will be described later and are formed obliquely so as to spread each other.
One end of each is connected. The thermal radiator 27 reflects the heat radiation from the silicon melt 12 and stores the radiation heat from the silicon melt 12. By moving to the vicinity of the silicon single crystal ingot 25, the heat radiator 27 prevents the heat of the silicon melt 12 from being dissipated into the chamber 11, and at the same time, the heat is radiated from the outer peripheral surface of the grown silicon single crystal ingot 25. The amount of heat is suppressed, and in particular, the solid-liquid interface when forming the straight body portion 25c (FIG. 1) is maintained in the same manner as when forming the shoulder portion.

Returning to FIG. 1 and FIG. 2, a pair of heat radiator moving means 41 is provided at the upper part of the chamber 11 so as to sandwich the casing 21. The heat radiator moving means 41 includes a drive gear provided in the upper portion of the chamber 11, a drive motor 46 provided in the upper portion of the chamber 11 and driving the drive gear,
It has a support rod 42 around which a rack gear that is suspended from the upper portion of the chamber 11 and meshes with a drive gear is formed, and a connecting wire 44 that connects the lower end of the support rod 42 and the heat radiator. The drive gear is built in a gear box 43 provided at the upper part of the chamber 11, and the connecting wire 44 is provided at the turning roller 26e provided outside the cylindrical portion 26a.
(Fig. 3), the direction is changed and the wires are installed. The heat radiator moving means 41 includes a rotating shaft 46 driven by a drive motor 46.
The rotation of a rotates a drive gear (not shown) built in the gear box 43, and the support rod 42 is moved up and down to move the heat radiating bodies 27 via the connecting wires 44, respectively, and the state shown by the solid line in FIG. To the state shown by the broken line, the distances of the plurality of heat radiators 27 to the peripheral surface of the silicon single crystal rod 25 can be changed.

On the other hand, a rotary encoder (not shown) is provided on the output shaft (not shown) of the pulling motor in the pulling means 22, and the weight of the silicon melt 12 in the quartz crucible 13 is provided in the crucible lifting means 17. There is provided a weight sensor (not shown) for detecting the position and a linear encoder (not shown) for detecting the vertical position of the support shaft 16. Each detection output of the rotary encoder, the weight sensor and the linear encoder is connected to a control input of a controller (not shown),
The control output of the controller is connected to the pulling motor of the pulling means 22, the raising / lowering motor of the crucible raising / lowering means 17, and the drive motor 46 of the heat radiation body moving means 41, respectively.
In addition, the controller is provided with a memory (not shown),
In this memory, the winding length of the wire cable 23 with respect to the detection output of the rotary encoder, that is, the pulling length of the silicon single crystal rod 25 is stored as a first map, and the silicon melting inside the quartz crucible 13 with respect to the detection output of the weight sensor is stored. The liquid level of the liquid 12 is stored as the second map.
The controller controls the raising / lowering motor of the crucible raising / lowering means 17 so that the liquid level of the silicon melt 12 in the quartz crucible 13 is always kept at a constant level based on the detection output of the weight sensor, and at the same time, the plurality of heat radiators 27 is configured to control the drive motor 46 of the heat radiator moving means 41.

A method for pulling a silicon single crystal according to the present invention using the apparatus thus configured will be described. As shown in FIG. 2, a high-purity silicon polycrystal is put into a quartz crucible 13, and the high-purity silicon polycrystal is heated and melted by a carbon heater 18 to form a silicon melt 12. If the silicon polycrystal melts and the silicon melt 12 is stored in the quartz crucible 13, then the first and second
The inert gas is supplied into the casing 21 by opening the flow rate adjusting valves 31 and 32, and the gas evaporated from the surface of the silicon melt 12 is discharged together with the inert gas into the exhaust pipe 30.
To be discharged from.

Next, the wire cable 23 is fed out by a pulling motor (not shown) of pulling means to lower the seed crystal 24, and the tip of the seed crystal 24 is brought into contact with the silicon melt 12. After that, the seed crystal 24 is gradually pulled up to form the seed narrowing portion 25a, and then the seed crystal 24 is further pulled up to grow the shoulder portion 25b under the seed narrowing portion 25a. At the time of forming the shoulder portion 25b, the heat radiator moving means 41 moves the plurality of heat radiators 27 to a position on the heat dissipation suppressing portion 31 separated from the shoulder portion 25b. For this reason, the heat of the silicon melt 12 is positively dissipated to the shoulder 25b in the process of formation, and the shoulder 25b is quickly formed.

After the shoulder 25b is grown, the shoulder 2 is further pulled up by pulling up the seed crystal 24, as shown in FIG.
A straight body portion 25c is formed below 5b. This straight body part 25
When forming c, the heat radiator moving means 41 moves the support rod 42 downward to move the plurality of heat radiators 27 to the vicinity of the straight body portion 25c. The plurality of thermal radiators 27 located near the straight body portion 25c prevent the heat of the silicon melt 12 from being dissipated into the chamber 11 and also store the radiant heat from the silicon melt 12 to store the direct heat in the vicinity of the liquid surface. The amount of heat radiated from the outer peripheral surface of the portion 25c is suppressed, and the solid-liquid interface is maintained on a substantially flat surface as in the formation of the shoulder portion 25b. With the training of the straight body part 25c,
The surface of the silicon melt 12 is lowered, and a lifting motor (not shown) raises the crucible 13 in accordance with the amount of the melt 12 that is reduced, and the surface of the silicon melt 12 that is lowered as the seed crystal 24 is pulled up to a predetermined position. Keep it up.

[0022]

EXAMPLES Next, examples of the present invention will be described in detail together with comparative examples. <Example 1> As shown in FIG. 1, the inner diameter is 400 to 600.
mm quartz crucible 13 and the inner diameter of the tubular portion 26a is 300 to
Thermal shield 26 of 500 mm and height of 300-600 mm
In the silicon single crystal pulling apparatus 10 having the above, the cone-shaped heat dissipation suppressing portion 31 was formed below the cylindrical portion 26a. Six heat radiating bodies 27 are radially movably arranged in the heat radiation suppressing section 31, and the support rods 4 of the heat radiating body moving means 41 are arranged.
It was connected to the lower end of 2 via a connecting wire 44. As the heat radiator 27, one made of carbon having a thickness of about 50 to 80 mm was used. The pulling device 10 configured as described above is referred to as Example 1.

<Comparative Example 1> Although not shown, the pulling device was constructed in the same manner as in Example 1 except that the heat radiator 27 was not provided. This pulling device is referred to as Comparative Example 1.

<Comparative Test 1 and Evaluation> In the pulling apparatus of Example 1, the silicon melt at the solid-liquid interface at the substantially central portion of the silicon single crystal rod 25 having a diameter of the straight body portion of 300 to 350 mm and pulled up by 600 mm. Height to liquid surface (H)
And the distance between the heat radiation member 27 and the peripheral surface of the silicon single crystal rod were simulated by a heat conduction analysis program in consideration of radiation heat transfer. The result is shown in FIG.

As is clear from FIG. 5, the height of the solid-liquid interface at the approximate center of the silicon single crystal rod is low because the heat radiator 27 is close to the peripheral surface of the silicon single crystal rod near the silicon melt. Therefore, it can be seen that the height of the solid-liquid interface increases as the heat radiator 27 is separated from the peripheral surface of the silicon single crystal rod. Therefore, it was found that the solid-liquid interface shape is changed by moving the heat radiator.

This is because when the heat radiator 27 approaches the peripheral surface of the silicon single crystal rod near the silicon melt, the heat radiator 27
It is considered that this is because the radiant heat from the silicon melt 12 is stored to suppress the amount of heat released from the outer peripheral surface of the silicon single crystal rod 25 in the vicinity of the silicon melt 12. That is, the cooling rate in the substantially central portion of the silicon single crystal rod 25 is substantially equal to the cooling rate in the periphery of the silicon single crystal rod 25 which is surrounded by the plurality of heat radiating bodies 27 and whose heat radiation from the outer peripheral surface is suppressed. Therefore, it is considered that the shape of the solid-liquid interface becomes substantially flat and the height of the solid-liquid interface at the substantially central portion of the silicon single crystal ingot 25 becomes low. On the other hand, the heat radiator 27
Is separated from the peripheral surface of the silicon single crystal rod, the height of the solid-liquid interface becomes high because the heat is positively radiated from the outer peripheral surface of the silicon single crystal rod 25, and the solid-liquid interface is almost at the center portion. It is considered that the cooling rate is slower than the cooling rate on the outer peripheral surface of the silicon single crystal ingot 25 near the silicon melt 12.

<Comparative Test 2 and Evaluation> When the silicon single crystal rod 25 having a diameter of the straight barrel portion 25c of 300 to 350 mm was pulled at a pulling rate of 0.1 to 1.0 mm / min with the pulling device of Example 1. By moving the heat radiating body 27 so that the solid-liquid interface shape becomes substantially flat, the relationship between the height of the solid-liquid interface at the substantially central portion of the silicon single crystal rod 25 with respect to the silicon melt surface and the solidification rate is radiated. Simulation calculation was performed using a heat conduction analysis program that takes into consideration. The solidification rate is
The value obtained by dividing the weight of the pulled silicon single crystal rod 25 by the weight of the silicon melt 12 initially stored in the quartz crucible 13 was multiplied by 100. The relationship between the solidification rate and the distance of the heat radiation body 27 to the peripheral surface of the silicon single crystal rod 25 obtained as a result is shown in FIG. 6, and the solid-liquid interface in the substantially central portion of the silicon single crystal rod is higher than the silicon melt surface. The solid line in FIG. 7 shows the relationship between the hardness (H) and the solidification rate.

As is apparent from FIG. 6, at the beginning of pulling up the silicon single crystal rod 25, the peripheral surfaces of the heat radiation body 27 and the silicon single crystal rod 25 are separated from each other, and the distance becomes smaller as the pulling is performed. I understand. Further, by moving the heat radiating body 27 in this manner, it is understood that the solid-liquid interface shape is maintained substantially flat as shown in FIG.

<Comparative Test 3 and Evaluation> A silicon single crystal ingot was pulled up by the pulling apparatus of Comparative Example 1 under the same conditions as in Comparative Test 2, and the height (H) of the solid-liquid interface with respect to the surface of the silicon melt and the solidification rate. The relationship between and was calculated by simulation with a heat conduction analysis program considering radiative heat transfer. The result is shown by a broken line in FIG.

As is apparent from the broken line in FIG. 7, it is understood that in Comparative Example 1, the height of the solid-liquid interface with respect to the surface of the silicon melt rises as the silicon single crystal rod is pulled up. This means that the solid-liquid interface changes so as to stick out upward, and it can be seen that the solid-liquid interface shape changes as the silicon single crystal rod is pulled up.

[0031]

As described above, according to the present invention, a cone-shaped heat radiation suppressing portion inclined downward so that the opening diameter becomes smaller as it goes downward is formed in the lower portion of the heat shielding member, and a plurality of heat radiation suppressing members are formed. The heat radiator is radially movably arranged on the heat dissipation suppressing portion so as to surround the silicon single crystal rod, and the plurality of heat radiators are respectively moved to the peripheral surface of the silicon single crystal rod of the plurality of heat radiators. Since the thermal radiator moving means for changing the distance is provided, in the vicinity of the solid-liquid interface of the silicon single crystal rod pulled up from the silicon melt, the temperature of the thermal radiator rises due to the radiant heat from the high-temperature silicon melt, or Alternatively, the radiant heat from the silicon melt or the heat radiation from the silicon single crystal rod is reflected by the thermal radiation body to suppress rapid heat radiation from the outer peripheral surface of the silicon single crystal rod near the silicon melt. Can. As a result, the occurrence of thermal stress in the silicon single crystal rod can be reduced by preventing a sharp temperature decrease in the outer peripheral portion of the silicon single crystal rod and making the solid-liquid interface shape substantially uniform. Further, since a plurality of thermal radiators are arranged on the heat dissipation suppressing portion so as to be radially movable, even when pulling a plurality of types of silicon single crystal rods having different straight body diameters, the plurality of thermal radiators are respectively separated. By moving and changing the diameter of the opening surrounded by the plurality of heat radiators, the plurality of heat radiators can be arranged in accordance with the straight diameter of the silicon single crystal rod to be pulled. As a result, the same heat shield member can be used, and the apparatus of the present invention can pull up a plurality of types of silicon single crystal rods having different straight body diameters without replacing the heat shield member.

Further, the heat radiator moving means is provided with a drive gear provided on the upper part of the chamber, a drive motor provided on the upper part of the chamber to drive the drive gear, and a drive gear suspended from the upper part of the chamber into the chamber. If there is a support rod around which a rack gear that meshes with is formed, and a connecting wire that connects the lower end of the support rod and the heat radiator, the support rod moves up and down due to the rotation of the drive gear that meshes with the rack gear. , The heat radiator can be moved easily.

Furthermore, if a plurality of heat radiators are moved to positions away from the shoulders when forming the shoulders, the heat of the silicon melt is positively dissipated to the shoulders in the process of forming the shoulders. If a plurality of heat radiators are moved to the vicinity of the straight body portion when forming the straight body portion, the rapid heat dissipation from the outer peripheral surface of the silicon single crystal rod in the vicinity of the silicon melt is suppressed to suppress the silicon single crystal. The solid-liquid interface shape can be easily made substantially flat by preventing a rapid temperature decrease in the outer peripheral portion of the rod.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram showing a pulling device of the present invention in which a straight body portion of a silicon single crystal ingot is pulled up.

FIG. 2 is a sectional configuration diagram corresponding to FIG. 1, showing a state in which a shoulder portion is pulled up.

FIG. 3 is a cross-sectional view of a heat shield member in which a heat radiator is arranged on the heat radiation suppressing portion.

FIG. 4 is a cross-sectional view taken along the line AA of FIG. 1 showing an arrangement state of the heat radiator.

FIG. 5 is a diagram showing the relationship between the height of the solid-liquid interface in the substantially central portion of the silicon single crystal ingot with respect to the surface of the silicon melt, and the distance of the heat radiator to the peripheral surface of the silicon single crystal ingot.

FIG. 6 is a diagram showing a relationship between a solidification rate and a distance of a heat radiator to a peripheral surface of a silicon single crystal rod.

FIG. 7 is a diagram showing the relationship between the height of the solid-liquid interface in the substantially central portion of the silicon single crystal ingot with respect to the surface of the silicon melt and the solidification rate.

FIG. 8 is a sectional configuration diagram corresponding to FIG. 1, showing a conventional silicon single crystal pulling apparatus.

[Explanation of symbols]

10 Lifting device 11 chambers 12 Silicon melt 13 Quartz crucible 18 heater 25 Silicon single crystal rod 26 Heat shield 26c Heat dissipation suppressing section 27 Heat radiator 41 Heat radiator moving means 42 Support rod 44 connecting wire 46 Drive motor

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yasushi Shimanuki 1-5-1 Otemachi, Chiyoda-ku, Tokyo Mitsubishi Materials Silicon Co., Ltd. (56) Reference JP-A-5-330975 (JP, A) JP JP-A-1-100086 (JP, A) JP-A-6-256084 (JP, A) JP-A-9-227272 (JP, A) JP-A-9-309789 (JP, A) JP-A-9-315882 (JP , A) JP 11-157993 (JP, A) JP 11-263692 (JP, A) International Publication 93/00462 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) ) C30B 1/00-35/00

Claims (3)

(57) [Claims] 1. A silicon melt provided in the chamber (11).
(12) is stored in the quartz crucible (13), and the quartz crucible (1
A heater (18) that surrounds the outer peripheral surface of 3) and heats the silicon melt (12), and a lower end that surrounds the outer peripheral surface of the silicon single crystal rod (25) pulled from the silicon melt (12). A silicon single crystal pulling device provided with a cylindrical heat shield member (26) configured to be positioned above the surface of the silicon melt (12) with a space between them and shield the radiant heat from the heater (18). In the above, the cone-shaped heat dissipation suppressing portion (26c) inclined downward so that the opening diameter becomes smaller as it goes downward is the heat shielding member.
(26) is formed in the lower portion, a plurality of thermal radiators (27) are radially movably arranged on the heat dissipation suppressing portion (26c) so as to surround the silicon single crystal rod (25), Each of the heat radiators (27) is moved to change the distance of the plurality of heat radiators (27) to the peripheral surface of the silicon single crystal rod (25). A device for pulling a silicon single crystal. 2. A heat radiant body moving means (41) is provided in the chamber.
The drive gear provided on the upper part of (11) and the chamber (11)
A drive motor (4
6), a support rod (42) around which a rack gear that is suspended from the upper part of the chamber (11) and meshes with the drive gear is formed, and the lower end of the support rod (42) And a connecting wire (44) for connecting the heat radiation body (27).
The apparatus for pulling a silicon single crystal described. 3. A cylindrical heat shield member (26) is provided with a silicon single crystal rod (25) grown from a silicon melt (12) stored in a quartz crucible (13) and a lower portion of the heat shield member (26). It is surrounded by a downwardly inclined cone-shaped heat dissipation suppressing part (26c), and the silicon single crystal rod (2
5) is a method of pulling the silicon single crystal rod (25) by arranging a plurality of thermal radiators (27) so as to be radially movable so as to surround the silicon single crystal rod (25). When forming the portion (25b), the plurality of heat radiators (27) are placed on the heat radiation suppressing portion (26c) and the shoulder portion.
(25b) moved to a position away from, the plurality of thermal radiators (27) in the vicinity of the straight body portion (25c) when forming the straight body portion (25c) of the silicon single crystal rod (25) And a method for pulling a silicon single crystal.