JPH11255576A - Apparatus for pulling silicon single crystal and pulling up thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of a thermal stress in a silicon single crystal rod by uniformizing a temperature gradient in the vertical direction in the central part of a straight trunk part of the silicon single crystal rod during the pulling up. SOLUTION: This apparatus for pulling a silicon single crystal is equipped with a crucible lifting or lowering means 17 for lifting or lowering a quartz crucible 13 storing a silicon melt 12 therein and a cylindrical heat shielding unit 26 surrounding a silicon single crystal rod 25 grown from the silicon melt 12. The heat shielding unit 26 is provided with an annular heat radiating unit 27 having an area covering a space between the inner surface of the quartz crucible 13 and the outer surface of the heat shielding unit 26. The heat radiating unit 27 is lifted or lowered respectively independently of the heat shielding unit 26 and the crucible lifting or lowering means 17 by a means 41 for lifting or lowering the heat radiating unit 27. One or more through-holes are preferably formed in the heat radiating unit 27, which is arranged at the top or upper part of the quartz crucible 13 when forming the shoulder part 25b of the silicon single crystal rod 25 and further arranged near the liquid surface of the silicon melt 12 when forming a straight trunk part 25c.

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 and method for pulling and growing a silicon single crystal rod.

[0002]

2. Description of the Related Art As a method for growing a silicon single crystal rod, a Czochralski method (hereinafter referred to as CZ) for growing a high-purity silicon single crystal rod for a semiconductor from a silicon melt in a crucible.
Is known). In this CZ method, a silicon heater in a quartz crucible is heated by a carbon heater provided around the quartz crucible to maintain the silicon melt at a predetermined temperature, and a mirror-etched seed crystal is brought into contact with the silicon melt,
The seed crystal is pulled up to grow a silicon single crystal rod. In this method of growing a silicon single crystal rod, a seed crystal is pulled up to form a seed drawing portion from a silicon melt, and then the crystal is gradually thickened to the diameter of the target silicon single crystal rod to form a shoulder, Thereafter, it is further pulled up to form a straight body of the silicon single crystal rod.

In order to improve the quality and productivity of a silicon single crystal rod in the CZ method, a conventional apparatus of this type includes a crucible for raising or lowering a quartz crucible for storing a silicon melt provided in a chamber. 2. Description of the Related Art There is known an apparatus provided with an elevating means and a cylindrical heat shield surrounding a silicon single crystal rod grown from a silicon melt. The crucible raising / lowering means raises the quartz crucible to prevent the surface of the silicon melt from lowering due to the pulling of the silicon single crystal rod, and obtains a uniform silicon single crystal rod while maintaining the surface of the silicon melt at a predetermined position. At the same time, the heat shield surrounds the silicon single crystal rod, shields the heat of the silicon melt from reaching the grown silicon single crystal rod, improves the cooling rate of the silicon single crystal rod, and pulls it up Increasing the speed and increasing the productivity of silicon single crystal rods.

[0004]

However, in the conventional pulling of a silicon single crystal, the heat shielding effect of the heat shield of the silicon melt is poor. In particular, the cooling of the silicon single crystal rod near the silicon melt is insufficient. Did not. For this reason,
There is a problem that the temperature gradient fluctuates near the solid-liquid interface in the axial direction at the center of the silicon single crystal rod. On the other hand, as the diameter of the silicon single crystal rod increases, the fluctuation of the axial temperature gradient at the center of the silicon single crystal rod is expected to further increase. For this reason, there is a possibility that thermal stress is generated in the silicon single crystal rod due to the fluctuation of the temperature gradient. An object of the present invention is to reduce the occurrence of thermal stress in a silicon single crystal rod by making the temperature gradient near the solid-liquid interface in the axial direction near the center of the silicon single crystal rod being pulled from the silicon melt uniform. An object of the present invention is to provide a silicon single crystal pulling apparatus and a pulling method thereof that can be suppressed.

[0005]

The invention according to claim 1 is
As shown in FIG. 1, crucible lifting / lowering means 17 for raising / lowering quartz crucible 13 for storing silicon melt 12,
This is an improvement in a silicon single crystal pulling apparatus provided with a cylindrical heat shield 26 surrounding a silicon single crystal rod 25 grown from the silicon melt 12. The characteristic configuration has an annular heat radiator 27 having an area in which the heat shield 26 covers an inner surface of the quartz crucible 13 and an outer surface of the heat shield 26, and the heat radiator 27 is connected to the heat shield 26 and Heat radiation body elevating means 4 for raising or lowering independently of crucible elevating means 17
There is one. The heat radiator 27 dissipates the heat of the silicon melt 12 into the chamber by raising or lowering the heat radiator 27 independently of the heat shield 26 and the crucible lifting means 17 by the heat radiator raising / lowering means 41. And cooling of the silicon single crystal rod 25 grown together with the heat shield 26 is promoted, and the temperature gradient in the axial direction at the center of the silicon single crystal rod 25 when the straight body portion 25c is formed is made uniform.

The invention according to claim 2 is the invention according to claim 1, wherein the heat radiator elevating means 41 is suspended from the upper part of the chamber 11, a rack gear is formed around the chamber, and the heat radiator 27 is provided at the lower end. A mounted support rod 42, a gear box 43 provided at the upper part of the chamber 11 and having a drive gear meshing with the rack gear, and a gear box 43 for moving the support rod 42 up and down by rotation of the drive gear, and provided at the upper part of the chamber 11 And a driving motor 46 for driving the driving gear. Since the support rod 42 is moved up and down by the rotation of the drive gear meshing with the rack gear, the position of the heat radiator 27 can be easily controlled.

A third aspect of the present invention is the invention according to the first or second aspect, wherein a silicon single crystal in which one or more through holes 27c are formed in a heat radiator 27 as shown in FIG. The lifting device. By forming one or more through-holes 27c in the heat radiator 27, an inert gas is allowed to flow through the through-holes 27c to effectively discharge the gas evaporated from the surface of the silicon melt 12 together with the inert gas. I do.

According to a fourth aspect of the present invention, a silicon single crystal is pulled while a silicon single crystal rod 25 growing from a silicon melt 12 stored in a quartz crucible 13 is surrounded by a cylindrical heat shield 26. This is an improvement in the method for pulling a single crystal. The characteristic point is that the inner surface of the quartz crucible 13 and the heat shield 26 during the formation of the shoulder 25b of the silicon single crystal rod 25 are formed.
An annular heat radiator 27 having an area covering the outer surface of the silicon crucible 13 is loosely fitted to the heat shield 26 and disposed above or above the quartz crucible 13. The heat radiator 27 is located near the liquid surface of the liquid 12. At the time of forming the shoulder portion 25b, the heat radiator 27 is disposed at the upper end or above the quartz crucible 13, and the silicon melt 1
2 is actively dissipated to the shoulder 25b in the process of forming, whereby the shoulder 25b is quickly formed, and the silicon melt 12 is formed when the straight body 25c of the silicon single crystal rod 25 is formed.
The heat radiator 27 is arranged near the liquid surface of the silicon melt 12.
Of the silicon single crystal rod 25 grown together with the heat shield 26 is promoted, and the heat of the central portion of the silicon single crystal rod 25 when the straight body 25c is formed is prevented. The temperature gradient in the axial direction is maintained as high as when the shoulder 25b is formed.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. As shown in FIGS. 1 to 3, 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 the outer surface of the quartz crucible 13 is covered with a graphite susceptor 14. Is done. The lower surface of the quartz crucible 13 is fixed to the upper end of a support shaft 16 via a graphite susceptor 14, and the lower portion of the support shaft 16 is connected to crucible lifting / lowering means 17. The crucible raising / lowering means 17 has a first rotation motor (not shown) for rotating the quartz crucible 13 and a lifting / lowering motor for moving the quartz crucible 13 up and down, and these motors can rotate the quartz crucible 13 in a predetermined direction. At the same time, it can be moved up and down. The outer peripheral surface of the quartz crucible 13 is surrounded by a carbon heater 18 at a predetermined interval from the quartz crucible 13,
The carbon heater 18 is surrounded by a heat retaining tube 19. The carbon heater 18 heats and melts the high-purity polycrystalline silicon charged in the quartz crucible 13 to form the silicon melt 12.

A cylindrical casing 21 is connected to the upper end of the chamber 11. The casing 21 is provided with a pulling means 22. The pulling means 22 includes a pulling head (not shown) rotatably provided at the upper end of the casing 21 in a horizontal state, a second rotation motor (not shown) for rotating the head, and a quartz crucible 13 from the head.
A wire cable 23 suspended toward the center of rotation of
And a pulling motor (not shown) provided in the head for winding or feeding the wire cable 23. At the lower end of the wire cable 23 is attached a seed crystal 24 for dipping in the silicon melt 12 and pulling up the silicon single crystal rod 25.

Further, the chamber 11
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 having the other end connected to a vacuum pump (not shown)
And The supply pipe 29 and the discharge pipe 30 are provided with first and second flow control valves 31 and 32 for adjusting the flow rate of the inert gas flowing through these pipes 29 and 30, respectively.

On the other hand, between the outer peripheral surface of the silicon single crystal rod 25 and the inner peripheral surface of the quartz crucible 13, the silicon single crystal rod 2
5 is provided with a tubular heat shield 26. The heat shield 26 transfers the heat of the silicon melt 12 to the silicon single crystal rod 25.
The heat shield 26 is provided with a flange portion 26a extending outward in a substantially horizontal direction at an upper edge thereof. The heat shield 26 is fixed in the chamber 11 by placing the flange portion 26a on the heat retaining tube 19, and the lower edge of the heat shield 26 is
3 is located above the surface of the silicon melt 12 stored by a predetermined distance.

An annular heat radiator 27 is loosely fitted to the heat shield 26. As shown in FIG. 5, the heat radiator 27 is provided with a heat insulating material 27 inside an annular carbon casing 27b.
a, and the heat radiator 27 is configured to have an area covering the inner surface of the quartz crucible 13 and the outer surface of the heat shield 26. As shown in FIGS. 4 and 5, the heat radiator 27 is provided with gas supply / discharge means 28 (FIGS. 1 to 3).
A plurality of through-holes 27c formed obliquely so as to spread from the lower part to the upper part in order to circulate the inert gas supplied by the heat radiating member 41 (FIGS. 1 to 3). A pair of support holes 27d to be supported
Is formed. The heat radiator 27 reflects the heat radiation from the silicon melt 12 and stores the radiant heat from the silicon melt 12. Thus, the heat radiator 27 prevents the heat of the silicon melt 12 from dissipating into the chamber 11 and promotes the cooling of the silicon single crystal rod 25 grown together with the heat shield 26, and in particular, the heat radiation of the straight body 25c. The temperature gradient in the axial direction of the silicon single crystal rod 25 at the time of formation (FIGS. 1 and 2) is maintained as high as that at the time of formation of the shoulder 25b (FIG. 3).

Returning to FIGS. 1 to 3, a pair of heat radiation body elevating means 41 is provided above the chamber 11 so as to sandwich the casing 21. The heat radiator elevating means 41 includes a support rod 42 having a rack gear (not shown) formed around the support rod 42 and a lower end inserted into the support hole 27 d of the heat radiator 27, and the chamber 11.
A gearbox 43 is provided at the upper part of the housing 11 and meshes with a rack gear. The gearbox 43 moves the support rod 42 up and down by the rotation of the drive gear. The gearbox 43 is mounted on the upper part of the chamber 11 via a support member 44 and the rotating shaft 46a is driven. And a drive motor 46 connected to the gear. A large-diameter portion 42 a is inserted through the support hole 27 d of the heat radiator 27 and is provided below the support rod 42.
Is formed, and the large-diameter portion 42a is configured to support the heat radiator 27 from below. Heat radiation body elevating means 41
The drive motor 46 rotates a rotation shaft 46 a to rotate a drive gear (not shown) built in the gear box 43, and moves the support rod 42 up and down to move the heat radiator 27.
Is configured to rise or fall.

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 on the crucible elevating means 17. 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 and lowering motor of the crucible lifting and lowering means 17, and the drive motor 46 of the heat radiator lifting and lowering means 41.
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 in 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 a second map.
The controller controls the elevating motor of the crucible elevating means 17 so as to always keep the liquid level of the silicon melt 12 in the quartz crucible 13 at a constant level based on the detection output of the weight sensor, and controls the heat radiator 27. Crucible lifting means 17
Means 4 for raising and lowering the heat radiator independently
It is configured to control one drive motor 46.

A method for pulling a silicon single crystal according to the present invention using the above-configured apparatus will be described. As shown in FIG. 3, 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. When the silicon polycrystal is melted, the heat radiator elevating means 41 moves the support rod 42 upward, and in this embodiment, the heat radiator 27 is disposed above the quartz crucible 13. If the silicon polycrystal is melted and the silicon melt 12 is stored in the quartz crucible 13, then the first and second
By opening the flow control valves 31 and 32, an inert gas is supplied into the casing 21 and the gas evaporated from the surface of the silicon melt 12 is discharged together with the inert gas into the discharge pipe 30.
To be discharged from

Next, the wire 19 is drawn out by a pulling motor (not shown) of the 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. Thereafter, the seed crystal 24 is gradually pulled up, and the seed drawing portion 25a
Is formed, the seed crystal 24 is further pulled up to first grow a shoulder 25b below the seed drawing portion 25a. When the shoulder 25b is formed, the heat radiator 27 is arranged above the quartz crucible 13, so that the silicon melt 1
The heat of No. 2 is actively dissipated to the shoulder 25b being formed, and the formation of the shoulder 25b is performed promptly.

Once the shoulder 25b is grown, as shown in FIG.
A straight body 25c is formed below 5b. This straight body 25
When forming c, the heat radiator elevating means 41 moves the support rod 42 downward, and arranges the heat radiator 27 in advance near the liquid surface of the silicon melt 12. The heat radiator 27 located near the liquid surface of the silicon melt 12 prevents the heat of the silicon melt 12 from directly dissipating to the straight body portion 25c, and cools the silicon single crystal rod 25 grown together with the heat shield 26. And the temperature gradient in the axial direction of the central portion of the single crystal rod 25 at the time of forming the straight body portion 25c is maintained as high as that at the time of forming the shoulder portion 25b.

As the straight body portion 25c grows, the surface of the silicon melt 12 lowers, and a raising / lowering motor (not shown) raises the crucible 13 according to the decreasing amount of the melt 12, as shown in FIG. Then, the surface of the silicon melt 12 which is lowered as the seed crystal 24 is pulled is maintained at a predetermined position. Despite the rise of the quartz crucible 13, the heat radiating body elevating means 4
1 keeps the heat radiator 27 near the liquid surface of the silicon melt 12. The heat radiator 27 located near the liquid surface of the silicon melt 12 prevents the heat of the silicon melt 12 from directly dissipating to the straight body portion 25c, and cools the silicon single crystal rod 25 grown together with the heat shield 26. This promotes uniformity of the temperature gradient at the solid-liquid interface in the axial direction at the center of the straight body 25c.

In the above-described embodiment, the heat radiator 27 in which the heat insulating material 27a is filled in the inside of the annular carbon casing 27b is used, but the heat radiator is used to transfer the silicon melt 12 into the chamber 11. As long as heat radiation can be prevented, an annular plate made of molybdenum as shown in FIGS. 6 and 7 may be used. Such a plate-shaped heat radiator 47
Is provided with a plurality of through holes 47c for passing the inert gas supplied by the support holes 47d and the gas supply / discharge means.
Can be formed by punching or partially rising.

In the above-described embodiment, the shoulder 25
In forming b, the heat radiator 27 is arranged above the quartz crucible 13, but the heat radiator 27 may be arranged at the upper end of the quartz crucible 13. If the heat radiator 27 is arranged at the upper end of the quartz crucible 13, the heat radiator 27 located at the upper end of the quartz crucible 13 prevents the heat of the silicon melt 12 from dissipating into the chamber 11, and Heat is efficiently transmitted to the silicon melt 12 via the quartz crucible 13, and the silicon melt 12 can be brought to a predetermined temperature with a small amount of electric power.

[0022]

Next, examples of the present invention will be described in detail together with comparative examples. Embodiment 1 As shown in FIG. 1, a silicon single crystal pulling apparatus 1 having a quartz crucible 13 having an inner diameter of about 400 mm and a heat shield 26 having both an inner diameter and a height of about 400 mm.
0, an annular heat radiator 2 having an area covering an inner surface of the quartz crucible 13 and an outer surface of the heat shield 26 and having a thickness of about 38 mm.
7 was loosely fitted to the heat shield 26 and hung on the support rod 42 of the heat radiator elevating means 41. This heat radiator 27 has a thickness of about 22 m.
m, which was made by filling a heat insulating material 27a into an annular carbon casing 27b. The pulling device 10 thus configured was referred to as Example 1. <Comparative Example 1> A pulling device was constructed in the same manner as in Example 1 except that the heat radiator 27 was not provided, although not shown. This pulling device was designated as Comparative Example 1.

<Comparative Test and Evaluation> A silicon single crystal rod having a diameter of 300 mm in a straight body portion was pulled up to 200 mm at a pulling speed of 0.4 mm / min by each pulling device of Example 1 and Comparative Example 1.
The temperature gradient in the vicinity of the solid-liquid interface in the axial direction of the silicon single crystal rod when the silicon single crystal rod was pulled up by 600 mm and 1000 mm was simulated by a heat conduction analysis program in consideration of radiant heat transfer, and compared. The result is shown in FIG.
As is clear from FIG. 8, in Comparative Example 1, the maximum value was obtained when the silicon single crystal rod was pulled up by 200 mm, and thereafter, the maximum value was 6 mm.
It shows the minimum value when it is pulled up by 00 mm, and is 1000
When it was raised by mm, it slightly increased. On the other hand, in Example 1, the point when the silicon single crystal rod was pulled up by 200 mm showed the minimum value, and then increased slightly when pulled up by 600 mm, and dropped slightly when pulled up by 1000 mm, and the value was almost uniform. It turns out that it is becoming. This is because in the first embodiment, the silicon radiator prevents the silicon melt from radiating into the chamber, prevents the heat of the silicon melt from directly dissipating to the straight body, and grows together with the heat shield. While cooling of the rod was promoted, in Comparative Example 1, heat was radiated from the silicon melt into the chamber, and this heat reduced the temperature gradient near the solid-liquid interface in the axial direction at the center of the straight body. Conceivable.

[0024]

As described above, according to the present invention, the heat shield has an annular heat radiator having an area covering the inner surface of the quartz crucible and the outer surface of the heat shield. Since the heat radiator is raised or lowered independently of the heat shield and the crucible lifting and lowering means by the raising and lowering means, the heat of the silicon melt is prevented from dissipating into the chamber, and the silicon grown together with the heat shield is grown. Cooling of the single crystal rod can be promoted, and the temperature gradient in the axial direction at the center of the single crystal rod when the straight body is formed can be maintained as high as when the shoulder is formed. Further, if one or more through holes are formed in the heat radiator, an inert gas can be passed through the through holes to effectively discharge the gas evaporated from the surface of the silicon melt together with the inert gas. it can.

Further, by disposing the heat radiator above or above the quartz crucible at the time of forming the shoulder portion of the silicon single crystal rod, the heat of the silicon melt can be actively dissipated to the shoulder portion during the formation, The shoulder can be formed quickly, and if a heat radiator is arranged near the liquid surface of the silicon melt when forming the straight body of the silicon single crystal rod, the heat of the silicon melt is directly radiated to the straight body Promotes cooling of the silicon single crystal rod grown with the heat shield, and increases the axial temperature gradient at the center of the single crystal rod at the time of forming the straight body as high as at the time of forming the shoulder. maintain. As a result, the temperature gradient near the solid-liquid interface in the axial direction at the center of the silicon single crystal rod can be made uniform, and the occurrence of thermal stress in the silicon single crystal rod can be suppressed.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of a silicon single crystal pulling apparatus of the present invention.

FIG. 2 is a cross-sectional configuration diagram corresponding to FIG. 1, showing a state where a straight body of a silicon single crystal rod is pulled up.

FIG. 3 is a cross-sectional configuration diagram corresponding to FIG. 1, showing a state in which a shoulder of a silicon single crystal rod is pulled up.

FIG. 4 is a plan view of the heat radiator.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

FIG. 6 is a plan view of another heat radiator.

FIG. 7 is a sectional view taken along line BB of FIG. 6;

FIG. 8 is a diagram showing a change in a temperature gradient in the vicinity of a solid-liquid interface in an axial direction of a central portion of a silicon single crystal rod with respect to a pulled length of the silicon single crystal rod.

[Explanation of symbols]

 Reference Signs List 10 silicon single crystal pulling device 11 chamber 12 silicon melt 13 quartz crucible 17 crucible lifting / lowering means 25 silicon single crystal rod 25b shoulder 25c straight body 26 heat shield 27 heat radiator 41 heat radiator lifting / lowering means 42 support rod 43 Gear box 46 Drive motor

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Yasushi Shimanuki 1-5-1, Otemachi, Chiyoda-ku, Tokyo Mitsubishi Materials Silicon Corporation

Claims (4)

[Claims] 1. A quartz crucible for storing a silicon melt (12).
(13) a crucible lifting / lowering means (17) for raising or lowering, and a silicon heat shield (26) surrounding a silicon single crystal rod (25) grown from the silicon melt (12). In the single crystal pulling apparatus, the heat shield (26) has an annular heat radiator (27) having an area covering an inner surface of the quartz crucible (13) and an outer surface of the heat shield (26). And a heat radiator elevating means (41) for raising or lowering the heat radiator (27) independently of the heat shield (26) and the crucible elevating means (17). Equipment for pulling silicon single crystals. 2. The heat radiator lifting / lowering means (41) includes a chamber (11).
A support rod (42) suspended from the upper part of the rack, a rack gear is formed around it, and a heat radiator (27) is attached to the lower end, and a drive gear provided on the upper part of the chamber (11) and meshing with the rack gear. A gear box (43) which is built-in and moves the support rod (42) up and down by rotation of the drive gear, and a drive motor (46) provided on an upper portion of the chamber (11) and driving the drive gear. Item 2. An apparatus for pulling a silicon single crystal according to Item 1. 3. A heat radiator (27) having one or more through holes (27).
3. The apparatus for pulling a silicon single crystal according to claim 1, wherein c) is formed. 4. A method of pulling a silicon single crystal rod (25) growing from a silicon melt (12) stored in a quartz crucible (13) in a state surrounded by a cylindrical heat shield (26), When forming the shoulder portion (25b) of the silicon single crystal rod (25), an annular heat radiator (27) having an area covering an inner surface of the quartz crucible (13) and an outer surface of the heat shield (26) is formed. The heat shield (26)
And placed at the upper end or above the quartz crucible (13), and at the time of forming the straight body (25c) of the silicon single crystal rod (25), the heat near the liquid surface of the silicon melt (12) is formed. A method for pulling a silicon single crystal, comprising disposing a radiator (27).