JPH08310893A - Method for growing single crystal and apparatus therefor - Google Patents

Abstract

PURPOSE: To prevent polycrystallization, to improve the controllability of a diameter and to obtain a single crystal having decreased defects by immersing the front end of a cylindrical body of a bore larger than the target diameter of a grown crystal into a melt and adjusting the numbers of revolutions of a crucible, crystal and cylindrical body. CONSTITUTION: The cylindrical body is arranged around the grown crystal as shown in Fig. at the time of executing the crystal growth by pulling up the crystal from the raw material melt by a Czochralski method or liquid sealing Czochralski method. The bottom end of this cylindrical body is immersed into the raw material melt, by which the natural convection near the melt surface is shut off. In addition, the flow of the high-temp. melt is expanded up to the outer side of the grown crystal by the force convection generated by the cylindrical body and the local temp. rise in the peripheral part of the solid-liquid boundary is prevented, by which the recessing of the boundary is prevented. The cylindrical body is formed to the bore larger by 5 to 20mm than the target diameter in the straight barrel part of the grown crystal. A liquid sealant is housed onto the raw material melt and the wall of the raw material melt of a high temp. having high thermal conductivity is formed upper than the solid-liquid boundary on the outer side of the cylindrical body, by which the temp. stability near the boundary is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an oxide single crystal by the Czochralski method or the liquid-encapsulated Czochralski method.
The present invention relates to a method and an apparatus for growing a compound semiconductor single crystal or the like.

[0002]

2. Description of the Related Art Generally, a single crystal bulk of GaAs or the like grows by the Czochralski method (CZ method) or the liquid-encapsulated Czochralski method (LEC method), but polycrystals are partially generated during the growth. There was a problem. FIG. 7 shows a conventional LE.
It is a conceptual diagram of the apparatus which implements C method. In this device, a crucible 5 provided with a susceptor 4 is supported by a lower shaft 3 in the center of a high-pressure chamber 1, a raw material melt 6 and a liquid sealant 7 are contained in the crucible 5, and the crucible 5 is held by an upper shaft 2. The seed crystal 8 thus obtained is immersed in the raw material melt 6 to pull up the single crystal 9. A heater 10 is arranged around the raw material melt 6, a heater 11 is arranged around the single crystal 9, and a heat insulating material 12 is arranged inside the high-pressure chamber 1.

The cause of the above polycrystallization is that the shape of the solid-liquid interface between the growing crystal and the raw material melt is dented in the peripheral portion of the growing crystal and propagates perpendicularly to the solid-liquid interface, as shown in FIG. It is considered that dislocations accumulate in the peripheral portion and become polycrystalline. Therefore, in order to prevent this kind of polycrystallization, it is necessary to prevent depression of the solid-liquid interface peripheral portion of the grown crystal.

As a method for preventing depression of the solid-liquid interface by the LEC method, the power of the heater installed near the solid-liquid interface is increased as much as possible to locally heat the side surface of the grown crystal to dissipate heat from the crystal to the side. A method to suppress it has been proposed [HITACHI CAB
LE REVIEW No. 9 (1990) 55].

[0005]

However, the above method has the following problems. In order to locally heat the side surface of the crystal, it is necessary to shorten the heater length to some extent and apply a large amount of power. As a result, the current density flowing through the heater becomes very large, and the life of the heater becomes very short.

Since the heater is heated through the susceptor for supporting the crucible, which is made of carbon or the like, the heat is conducted in the susceptor so that the heat is uniformly distributed in the vertical direction. Therefore, essentially no local heating is possible. Further, since the liquid sealant B ₂ O ₃ hardly transmits radiant heat, it is impossible to effectively heat the vicinity of the most important growth interface.

Since not only the peripheral portion of the crystal but also the entire side surface of the crystal is heated, heat radiation to the side is suppressed as a whole, and the solid-liquid interface is largely convex toward the melt side. Therefore, large residual strain remains in the grown crystal, and the in-plane uniformity of the characteristics of the wafer cut from the crystal deteriorates.

In the Czochralski method and the liquid-encapsulated Czochralski method, the controllability of the diameter of the grown crystal largely depends on the temperature distribution on the surface of the raw material melt, but in the conventional method, the temperature distribution is stable with good reproducibility. Difficult to hold in
In particular, when a large amount of raw material is used at one time and a crucible having a large diameter is used in order to increase the productivity of a single crystal, the diameter control becomes more difficult as the distance between the growing crystal and the crucible wall increases.

The liquid-encapsulated Czochralski method is usually used to grow a single crystal containing a volatile element. However, a grown crystal pulled from a liquid encapsulant is crystallized by evaporation of the volatile element from its surface. Has the problem of being damaged,
The surface temperature of the liquid sealant could not be raised so high. As a result, the temperature gradient in the growth axis direction cannot be made too small (the temperature gradient in the growth of a GaAs single crystal is usually about 100 ° C./cm), and large thermal stress is generated in the grown crystal, resulting in crystal defects (dislocations). ), And only crystals with a high residual strain were obtained.

Therefore, in order to carry out the liquid-encapsulated Czochralski method under a small temperature gradient, a large amount of the liquid encapsulant is used to grow most of the grown crystals covered with the liquid encapsulant. It was tried to do (FEC method: Fully Enca
However, since the liquid sealant B ₂ O ₃ has a very low thermal conductivity, the temperature response of the raw material melt surface deteriorates, and as a result, it becomes extremely difficult to control the crystal diameter. It was not a practical growth method.

In view of the above, the present invention solves the above-mentioned problems and suppresses the depression of the solid-liquid interface peripheral portion of the growing crystal to prevent polycrystallization, without relying on local heating of the solid-liquid interface. It is an object of the present invention to provide a method for growing a single crystal having excellent controllability of diameter even if a crucible having a large diameter is used and having few crystal defects, and an apparatus therefor.

[0012]

The present invention has succeeded in solving the above problems by adopting the following constitution. (1) In the single crystal growth method of pulling a crystal from a raw material melt by the Czochralski method, the tip of a cylindrical body having an inner diameter larger than the target diameter of the straight body of the growing crystal is immersed in the raw material melt, A single crystal characterized by pulling the crystal while preventing depression of the solid-liquid interface shape by adjusting the rotational speed of at least one of the crucible containing the melt, the growing crystal and the cylindrical body. How to grow.

(2) In the method of growing a single crystal in which a crystal is pulled from a raw material melt by the liquid-encapsulated Czochralski method, the tip of a cylindrical body having an inner diameter larger than the target diameter of the straight body portion of the growing crystal is placed in the raw material melt. By immersing the crystal in a crucible for containing the raw material melt, adjusting the number of revolutions of any one or more of the growing crystal and the cylindrical body, the crystal is pulled up while preventing the depression of the solid-liquid interface shape, A method for growing a single crystal, which comprises retaining the temperature of a pulled crystal with a liquid sealant in a cylinder.

(3) Use of the cylindrical body having an inner diameter larger than the target diameter of the straight body portion of the growing crystal by 5 to 20 mm.
The method for growing a single crystal according to (1) or (2).

(4) Instead of the cylindrical body described in (1) or (2) above, a cylindrical body having the same cross-sectional shape as the crystal habit of the growing crystal,
A method for growing a single crystal, characterized in that a cylinder having an elliptical cross section is used in crystal growth for cutting a wafer in a direction not perpendicular to the growth axis.

(5) Any one of the above (1) to (4), characterized in that the lower end of the cylindrical body is bent slightly inward to prevent natural convection on the outside of the cylindrical body from wrapping around. 2. A single crystal growth apparatus according to any one of the above.

(6) The method for growing a single crystal according to any one of the above (1) to (5), characterized in that the cylindrical body is heated.

(7) One of the above (1) to (6), characterized in that the upper end of the cylinder is closed and the vapor pressure of the volatile element constituting the grown crystal is applied to the cylinder. The method for growing a single crystal according to.

(8) The diameter of the grown crystal is controlled by adjusting the relative rotational speed between the cylindrical body and the upper shaft.
The method for growing a single crystal according to any one of (1) to (7).

(9) In a single crystal growth apparatus for pulling a crystal from a raw material melt by the Czochralski method or the liquid sealed Czochralski method, a cylindrical body having an inner diameter larger than the target diameter of the straight body of the grown crystal is used. The tip is supported so as to be immersed in the raw material melt, the crucible containing the raw material melt is supported by a lower shaft so that the crucible can be raised and lowered, and the seed crystal is supported by the lower end of the upper shaft so that the seed crystal can be raised and lowered. A single crystal growth apparatus comprising means for adjusting the number of rotations of the upper and lower shafts and the ascending / descending speed in response to changes in

(10) Instead of the cylindrical body described in (9) above, a cylindrical body having the same cross-sectional shape as the crystal habit of the growing crystal, or a cross-section for crystal growth for cutting a wafer in a direction not perpendicular to the growth axis is used. An apparatus for growing a single crystal characterized by using an elliptic cylinder.

(11) The cylindrical body has a lower end bent slightly inward to prevent natural convection on the outside of the cylindrical body from coming inward. Ten)
A single crystal growth apparatus as described.

(12) The apparatus for growing a single crystal according to any one of the above (9) to (11), characterized in that a heating means for the cylindrical body is additionally provided.

(13) A heater having a closed upper end is used as the tubular body, a reservoir containing a volatile element constituting a growing crystal is provided, and the reservoir is connected to the tubular body so as to be ventilated. The vapor pressure of the volatile element in the cylinder can be adjusted by adjusting the output.
(9) The single crystal growth apparatus as described in any one of (12).

(14) The apparatus for growing a single crystal according to any one of the above (9) to (13), wherein the cylindrical body is rotatably supported integrally with a pulling shaft.

(15) The weight and shape of the tubular body are adjusted so that the tubular body floats above the raw material melt and maintains the above-mentioned immersion conditions. ) Any one
A single crystal growth apparatus described in 1.

(16) The apparatus for growing a single crystal according to any one of the above (9) to (13), wherein the cylindrical body is rotatably supported independently of the vertical axis.

(17) The apparatus for growing a single crystal according to any one of the above (9) to (13), characterized in that the cylindrical body is fixed to a stationary portion of the growth apparatus.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventor investigated natural convection of a raw material melt when a single crystal was grown by the Czochralski method or the liquid sealed Czochralski method. , It was found that natural convection that rises near the side wall of the crucible and then flows toward the growing crystal and forced convection that swirls near the solid-liquid interface due to the rotation of the crystal. It is considered that due to these convections, the melt temperature in the vicinity of the outer periphery of the solid-liquid interface becomes high and the peripheral portion of the solid-liquid interface becomes concave.

In the present invention, when a cylindrical body is immersed in a raw material melt for crystal growth, if the diameter of the growing crystal approaches the inner diameter of the cylindrical body, the meniscus receives a force from the cylindrical body. The effect of suppressing fluctuations in diameter can be expected. However, since the force changes depending on the relative rotation speed of the cylinder and the grown crystal, it is desirable to adjust the rotation speed of the cylinder and / or the grown crystal so as to optimize the above effect.

Therefore, in the present invention, as shown in FIG. 1, by arranging a cylindrical body around the grown crystal and immersing the lower end in the raw material melt, natural convection near the surface of the raw material melt is blocked, Moreover, since the flow of the high-temperature melt can be expanded to the outside of the growing crystal by the forced convection by the cylindrical body, it is possible to prevent the local temperature rise in the peripheral portion of the solid-liquid interface, and the concave portion of the solid-liquid interface can be prevented. Succeeded in preventing this. Also,
Generally, when a crucible having a large diameter is used, it becomes difficult to control the diameter of the grown crystal, but in the method of the present invention, the diameter can be controlled even when the crucible having a large diameter is used, and the productivity of crystal growth can be improved. It became so. In addition, the cylindrical body is 5 to 20 m from the target diameter of the straight body part of the growing crystal.
It is preferable to use a cylindrical body having a large inner diameter of m, preferably 5 to 10 mm.

Further, in the present invention, as shown in FIG. 2, the liquid sealant is contained on the raw material melt, and a cylindrical body similar to that shown in FIG. 1 is immersed in the raw material melt and attached to the upper shaft. When the seed crystal is immersed in the raw material melt to grow the crystal and pull up to the straight body part,
As shown in FIG. 2, the thickness of the liquid sealant inside the cylinder is considerably thicker than when it was pulled up, but the thickness of the liquid sealant outside does not change. There is a large difference, and the surface of the raw material melt outside the cylinder is higher than inside due to the pressure difference inside and outside the cylinder. As a result, a wall of the high temperature raw material melt having a high thermal conductivity was formed above the solid-liquid interface on the outside of the cylinder, and the temperature stability near the solid-liquid interface could be improved.

Further, in the present invention, when the straight body part is pulled up, the thickness of the liquid sealant inside the cylindrical body can be considerably increased irrespective of the diameter of the crucible. It is possible to prevent evaporation of volatile elements from the surface of the grown crystal. As a result, the temperature gradient near the solid-liquid interface can be made gentle, and the thermal strain in the crystal can be significantly reduced. Even in such a state, since the diameter of the grown crystal can be easily controlled by the method of the present invention as described above, a single crystal having excellent crystallinity can be manufactured with high yield.

When the cylindrical body is heated, the heat retention of the liquid sealant and / or the pulled crystal in the cylindrical body is promoted,
Since the temperature gradient at the solid-liquid interface can be made gentle,
The same effect as above can be expected. Furthermore, when the lower end of the cylinder is slightly bent inward, natural convection can be prevented from entering the cylinder, and the effect of blocking natural convection is great.

On the other hand, by using a cylindrical body having a closed upper end, it is connected to a reservoir for accommodating the volatile elements constituting the grown crystal in a ventilable manner, and the output of a heater arranged around the reservoir is adjusted. Since the vapor pressure of the volatile element in the cylindrical body can be adjusted to prevent the volatile element from escaping from the growing crystal, a high-quality single crystal can be obtained even if the temperature gradient at the solid-liquid interface is gentle. it can. An airtight container that covers the entire crucible is provided with an opening / closing mechanism (for example, the container is divided into upper and lower parts, a saucer for accommodating the liquid sealant is provided at the upper end of the side wall of the lower container, and the lower end of the side wall of the upper container is sealed with the liquid. It is also possible to supply a volatile element vapor by providing a mechanism for maintaining airtightness by immersing it in the agent, but in the present invention, a relatively simple structure is obtained by attaching the reservoir to the cylindrical body. It enabled adjustment of the steam.

The shape of the cylinder used in the present invention is generally circular in cross section, but in the growth of a crystal having a strong crystal habit, the same shape as that of the crystal habit or the substrate is cut out in a direction not perpendicular to the growth axis. In growing such a crystal, it is preferable to use a cylinder having an elliptical cross section.

The method of installing the cylindrical body includes a method of floating the raw material melt, a method of being independent of the rotation of the crucible and the pulling shaft, and being fixed and held by an immovable member of the apparatus, and
There are a method of rotating integrally with the pull-up shaft and a method of rotating independently of the rotation of the pull-up shaft and the crucible.

The levitation method has the advantage that the immersion depth can be kept constant by adjusting the weight and shape of the cylindrical body. On the other hand, since the cylindrical body floats on the raw material melt, it rotates with the rotation of the liquid sealant, and therefore has no function of controlling forced convection. Also in the levitation method, it is preferable to hold the cylindrical body in the center by means of a support or the like in order to make the cylindrical body coincide with the central axis of the crucible.

The method of independently fixing and holding is to fix the upper end of the cylindrical body to a stationary member such as a heat insulating material in the chamber, as shown in FIG. In order to keep the immersion depth of the cylinder constant, it is necessary to match the decreasing speed of the melt depth with the ascending speed of the lower shaft. This method has a greater convection control effect than the above method.

The method of rotating integrally with the pulling shaft is shown in FIG.
As shown in, the upper end of the cylinder is supported by the upper shaft, and it is necessary to provide a moving mechanism for lowering the cylinder as the growing crystal is pulled up. When the cylinder is rotated together with the crystal, the convection control effect near the solid-liquid interface is greatest.
The method of rotating independently of the rotation of the pulling shaft and the crucible has an advantage that the rotation speed of the cylindrical body can be freely selected with respect to the rotation of the pulling shaft and the crucible. The cylindrical body of the present invention can be made of carbon, pBN, quartz or the like.

[0041]

【Example】

[Example 1] A GaAs single crystal was grown by the LEC method by floating a cylindrical body in a raw material melt. When a target body diameter of the grown crystal was 110 mm, a pBN cylinder having an inner diameter of 120 mm and a thickness of 1 mm was floated on the raw material melt, the immersion depth in the raw material melt was 10 mm. A pBN crucible having a carbon susceptor with an inner diameter of 200 mm was charged with 10 kg of GaAs raw material and 500 g of B ₂ O ₃ ,
The rotation speed of the crucible during growth of the straight body was 10 rpm, the rotation speed of the seed crystal was 2 rpm in the opposite direction, and the pulling speed was 5 mm /
Crystal growth was performed at H.

The obtained crystal was a single crystal having a length of 200 mm and a maximum diameter of 110 mm. In order to examine the shape of the solid-liquid interface of the single crystal, it was sliced along the growth axis, and HF40cc with a concentration of 50%, CrO ₃ 100 g, and water 5
When the wafer is dipped in an etching solution of 20 cc and etched for 10 minutes while irradiating with light to observe the growth fringes of the crystal, the periphery is almost horizontal as shown in FIG.
It can be seen that the depression around the solid-liquid interface was substantially suppressed.

Example 2 A GaAs single crystal was grown in the same manner as in Example 1 except that the cylindrical body was rotated at the same rotational speed as the pulling crystal of the upper shaft as shown in FIG. The upper shaft with a non-circular cross section was set through a hole of the same shape as the upper shaft cross-section opened in the upper part of the cylinder so that the rotation of the upper shaft could be transmitted to the cylinder. Also, make sure that the cylinder does not move up and down.
Supported by insulation. The amount of immersion of the cylinder was kept constant by raising the lower axis at the same rate as the rate of decrease in the depth of the raw material melt accompanying the growth of crystals. The obtained crystal was a single crystal having a length of 210 mm and a maximum diameter of 108 mm. When the growth stripes were observed in the same manner as in Example 1, as shown in FIG. 10, a tendency of convexity was observed in the peripheral portion of the solid-liquid interface, and the effect of forced convection by the cylindrical body was recognized.

Comparative Example 1 A GaAs single crystal was grown in the same manner as in Example 1 except that the cylindrical body was omitted. The obtained crystal had a length of 200 mm and a maximum diameter of 111 mm. When the growth fringes were observed in the same manner as in Example 1, as shown in FIG. 11, the peripheral portion of the solid-liquid interface was markedly prone to indentation,
Polycrystallization was recognized from the arrow part.

[Comparative Example 2] Further, when the inner diameter of the cylindrical body was made smaller than the target diameter of the crystal +5 mm, the crystal diameter did not readily increase to the target diameter, and when it was thickened excessively, it contacted the cylindrical body. The cylinder was lifted and crystal growth could not continue. On the other hand, the immersion depth of the cylinder is 10 mm, and the inner diameter is +20 from the target diameter of the crystal.
When the thickness was increased by mm, depression was observed around the solid-liquid interface as in Comparative Example 1, and polycrystals were generated as in Comparative Example 1.

Example 3 A GaAs single crystal was grown using the same apparatus as in Example 1 except that the cylindrical body was fixed to a heat insulating material so as not to rotate as shown in FIG. The rotation speed of the crucible was set to 10 rpm, and the rotation speed of the grown crystal was set to 2 rpm. The obtained crystal was a single crystal having a length of 200 mm and a maximum diameter of 110 mm. When the growth stripes were observed in the same manner as in Example 1, the shape of the peripheral portion of the solid-liquid interface was between Example 1 and Example 2. A (100) wafer was cut out from the obtained crystal and etched with molten KOH, and the in-plane distribution of dislocation density was investigated and shown in FIG. The in-plane average dislocation density was 57300 cm ^-2 .

Example 4 In Example 3, B ₂ O _{3 was used.}
Except that the input amount of was doubled from 500g to 1000g,
Crystal growth was performed in the same manner as in Example 3. At the time of crystal growth in the straight body part, the thickness of B ₂ O _{3 in} the cylinder was about twice that in Example 3. The obtained crystal was a single crystal having a length of 190 mm and a maximum diameter of 113 mm. The average diameter was slightly thicker because the cone portion grew slightly rapidly, but the diameter variation was at the same level as in Example 1, and the diameter controllability was extremely good. A (100) wafer was cut out from the obtained crystal and etched with molten KOH to examine the in-plane distribution of dislocation density. The results are shown in FIG. 12 in comparison with Example 3. B ₂ O
_As the thickness of ₃ increased, the temperature gradient in the growth axis direction decreased, and as a result, the dislocation density could be decreased. The in-plane average dislocation density was 29700 cm ^-2, which was smaller than that in Example 3.

[Embodiment 5] GaA was prepared in the same manner as in Embodiment 3 except that a cylindrical body having an upper end closed as shown in FIG. 3 was used, and an As reservoir was connected to the cylinder so that As vapor was loaded.
s single crystal was grown. The temperature gradient in the growth axis direction in B ₂ O ₃ before growth was about 100 ° C./cm in Example 3, whereas it was growth under As vapor pressure.
In Example 5, it could be suppressed to about 30 ° C./cm.

The obtained crystal was a single crystal having a length of 220 mm and a maximum diameter of 107 mm. Generally, when a GaAs single crystal was grown in a state where the temperature gradient was small, there was As loss, but the GaAs single crystal obtained here had a metallic luster on the surface, and no As evaporation was observed. Since the temperature gradient was small, the amount of protrusion in the central portion of the solid-liquid interface was small, but the peripheral portion of the solid-liquid interface was almost the same as in Example 3. A (100) wafer was cut out from the obtained crystal and etched with molten KOH, and the in-plane distribution of dislocation density was examined. As shown in FIG. 12, the dislocation density was further reduced as compared with Example 4. The in-plane average dislocation density was 7420 cm ^-2 .

Comparative Example 3 In Example 3, the rotational speed of the crucible was kept constant at 10 rpm and the rotational speed of the crystal was changed to examine the influence of the diameter controllability of the relative rotational speed of the crystal and the cylinder. That is, when the crystal rotation speed was increased from 2 rpm to 5 rpm (reverse rotation to the rotation direction of the crucible), the meniscus received too much force from the cylindrical body, and part of the meniscus dropped during growth. On the other hand, when the rotation of the crystal was stopped, the force applied to the meniscus was too small and the crystal diameter increased until it contacted the cylinder. The dropping of the meniscus is a phenomenon in which a part of the crystal is cut from the melt, and an egre is generated in the grown crystal.

[Example 6] In Example 3, a PBN cylindrical body coated with a carbon heater was used to heat the cylindrical body and rotate the crystal at a rotation speed of 5 rpm. Although similar results were obtained, even when the crystal growth was carried out while the rotation was stopped, the crystal diameter did not change and no contact with the cylinder was observed.

[0052]

According to the present invention, by adopting the above-mentioned constitution, it is possible to prevent depression of the peripheral portion of the solid-liquid interface of the growing crystal and prevent polycrystallization due to the accumulation of dislocations. . Further, the diameter controllability of the grown crystal was improved, and the crystal yield could be improved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a situation in which convection of a raw material melt changes in a cylindrical body of the present invention.

FIG. 2 is an explanatory diagram for explaining a state in the vicinity of a solid-liquid interface when a cylindrical body of the present invention is immersed in a raw material melt via a liquid sealing agent and a crystal in a straight body part is pulled up.

FIG. 3 is an explanatory diagram of a crystal growth apparatus in which an As reservoir is connected to the cylindrical body of the present invention.

FIG. 4 is a diagram illustrating a situation in which a peripheral portion of a solid-liquid interface of a grown crystal is recessed due to natural convection of a raw material melt in a conventional CZ method.

FIG. 5 is an explanatory diagram for fixing the cylindrical body of the present invention to a heat insulating material.

FIG. 6 is an explanatory diagram of a case where the cylindrical body of the present invention is supported by an upper shaft.

FIG. 7 is a conceptual diagram of an apparatus for performing a conventional LEC method.

FIG. 8 is a diagram for explaining a state of polycrystallization at a conventional solid-liquid interface.

FIG. 9 is a schematic view showing growth fringes of the crystal obtained in Example 1.

FIG. 10 is a schematic diagram showing growth fringes of the crystal obtained in Example 2.

FIG. 11 is a schematic diagram showing growth fringes of a crystal obtained in Comparative Example 1 (conventional LEC method).

FIG. 12: Cut out from the crystals obtained in Examples 3, 4, and 5.
3 is a graph showing in-plane distribution of dislocation density of a (100) wafer.

Claims (15)

[Claims] 1. In a method for growing a single crystal in which a crystal is pulled from a raw material melt by the Czochralski method, a tip of a cylindrical body having an inner diameter larger than a target diameter of a straight body portion of the grown crystal is immersed in the raw material melt. , A crucible for containing a raw material melt, a growing crystal, and the cylindrical body are adjusted to adjust the number of revolutions to pull up the crystal while preventing depression of the solid-liquid interface shape. Crystal growth method. 2. In a method for growing a single crystal in which a crystal is pulled from a raw material melt by a liquid-encapsulated Czochralski method, a tip of a cylindrical body having an inner diameter larger than a target diameter of a straight body portion of the grown crystal is in the raw material melt. By immersing in a crucible for containing the raw material melt, the growth crystal and the cylindrical body and adjusting the number of revolutions of at least one of them to pull up the crystal while preventing depression of the solid-liquid interface shape. A method for growing a single crystal, characterized in that the pulled crystal is kept warm with a liquid sealant in the body. 3. The method for growing a single crystal according to claim 1, wherein the inner diameter of the cylindrical body is 5 to 20 mm larger than the target diameter of the straight body portion of the grown crystal. 4. A cylinder having the same cross-sectional shape as the crystal habit of the growing crystal instead of the cylinder of claim 1 or 2, or a cross-section when growing a crystal for cutting a wafer in a direction not perpendicular to the growth axis. A method for growing a single crystal, characterized by using an elliptic cylinder. 5. The method for growing a single crystal according to claim 1, wherein the cylindrical body is heated. 6. The unit according to claim 1, wherein an upper end of the cylinder is closed and a vapor pressure of a volatile element forming a growing crystal is applied to the cylinder. Crystal growth method. 7. The diameter of the grown crystal is controlled by adjusting the relative rotational speed between the cylindrical body and the upper shaft.
7. The method for growing a single crystal according to any one of 6 above. 8. A single crystal growth apparatus for pulling a crystal from a raw material melt by the Czochralski method or the liquid sealed Czochralski method, wherein a cylindrical body having an inner diameter larger than the target diameter of the straight body portion of the grown crystal is used. The tip is supported so as to be immersed in the raw material melt, and the crucible for containing the raw material melt is supported by the lower shaft so as to be rotatable up and down, and the lower end of the upper shaft is supported so that the seed crystal can be rotated up and down. An apparatus for growing a single crystal, characterized in that means for adjusting the number of rotations of the upper and lower shafts and the ascending / descending speed in response to changes is provided. 9. Instead of the cylinder according to claim 8, a cylinder having the same cross-sectional shape as the crystal habit of the growing crystal, or an elliptical cross-section when growing a crystal for cutting a wafer in a direction not perpendicular to the growth axis. An apparatus for growing a single crystal, which is characterized by using a cylindrical body. 10. The apparatus for growing a single crystal according to claim 9, further comprising heating means for the cylindrical body. 11. A cylinder having a closed upper end is used as the cylinder, a reservoir containing a volatile element constituting a growing crystal is provided, and the reservoir is connected to the cylinder so as to be aerable.
11. The single crystal growth apparatus according to claim 8, wherein the heater output of the reservoir is adjusted to adjust the vapor pressure of the volatile element in the cylinder. 12. The single crystal growth apparatus according to claim 8, wherein the cylindrical body is rotatably supported integrally with the pulling shaft. 13. The weight and shape of the tubular body are adjusted so that the tubular body floats on the raw material melt and maintains the immersion conditions. 1
Item 5. A single crystal growth apparatus according to item. 14. The single crystal growth apparatus according to claim 8, wherein the cylindrical body is rotatably supported independently of the vertical axis. 15. The apparatus for growing a single crystal according to claim 8, wherein the cylindrical body is fixed to a non-moving part of the growth apparatus.