JPH10273376A - Production of single crystal and apparatus for producing single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To pull a single crystal of a large diameter and a heavy weight by increasing the strength of a neck part formed by the Dash method. SOLUTION: A seed crystal 1 is lowered so as to be dipped in a melt 2 in a quartz crucible 4 and a current is then applied to a coil 11 to generate a vertical type magnetic field. The seed crystal 1 is subsequently pulled up at a relatively high speed after the passage of a prescribed time to carry out the necking. When the necking is completed to start the formation of an upper conical part 15, the application of the vertical type magnetic field is stopped to apply a current in the opposite direction to the coils 11a and 11b to form a Cusp type magnetic field CM. The pulling up speed is slowly reduced in a state of the Cusp type magnetic field CM applied to the melt 2 to thereby form the upper conical part 15. The seed crystal 1 is then pulled at a prescribed speed in the state of the Cusp type magnetic field CMapplied thereto to thereby form a circular cylindrical body part 17.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a pulling CZ (Czoc).
The present invention relates to a single crystal manufacturing method and a single crystal manufacturing apparatus for manufacturing a dislocation-free single crystal of Si (silicon) by the hralski) method.

[0002]

2. Description of the Related Art In general, in a single crystal manufacturing apparatus by the pulling CZ method, a high pressure-resistant hermetic chamber is decompressed to about 10 torr to flow fresh Ar (argon) gas, and a quartz crucible provided below the chamber is provided. The polycrystal in is melted by heating, and the seed crystal is immersed in the surface of this melt from above,
The seed crystal and the quartz crucible are rotated and moved up and down, and the seed crystal is pulled up, so that a conical upper cone part whose upper end protrudes below the seed crystal, and a conical lower part whose cylindrical body part and lower end protrude It is configured to grow a single crystal (so-called ingot) composed of a cone portion.

[0003] In order to remove dislocations generated in the seed crystal by thermal shock when the seed crystal is immersed in the surface of the melt (to eliminate dislocations), as shown in FIG. 1 is immersed in the surface of the Si melt 2 and the pulling speed is relatively increased to form a neck portion 3 having a diameter smaller than that of the seed crystal, for example, 3 to 5 mm, and then the pulling of the upper cone portion is started. The dash (Dash) method is known.

Further, since a single crystal having a large diameter and a large weight (150 to 200 kg or more) cannot be pulled through the small diameter neck portion 3, for example, Japanese Patent Publication No.
As shown in Japanese Patent No. 5377, after forming a small-diameter neck portion 3 by the Dash method, the pulling speed is relatively slow to form a large diameter, and then the pulling speed is relatively high to form a small diameter. A method has been proposed in which a "constriction" is formed, and the constriction below the large-diameter portion is gripped by a gripper to pull up a large-diameter, heavy-weight single crystal. Further, as a conventional device for gripping the constriction, in addition to the above publication,
For example, Japanese Patent Publication No. 7-103000, Japanese Patent Publication No. 7-51
No. 5 is disclosed.

[0005] Further, as another conventional example, as described in, for example, JP-A-5-270974 and JP-A-7-172981, a method of holding the body portion without forming the above-mentioned "constriction", JP-A-63-252
No. 991, JP-A-5-270975, instead of the above-mentioned “constriction”, an “annular portion” having a larger diameter than the body portion is formed at the shoulder between the upper cone portion and the body portion, There has been proposed a method of gripping under the “annular portion”.

Further, when a single crystal is grown from the Si melt 2, microturbulence of crystal growth due to convection of the Si melt 2 poses a problem. For example, Japanese Patent Laid-Open No. 60-16891 discloses a method for preventing this. As disclosed in Japanese Patent Application Laid-Open Publication No. Hei 2-12920 and Japanese Patent Laid-Open Publication No. Sho 59-199597, by applying a vertical magnetic field, a transverse magnetic field, and a cusp-type magnetic field to the Si melt 2, MCZ (magnetic field applied C)
Z) The method is known. Here, in the method of applying a vertical magnetic field, the single crystal has a higher oxygen concentration than other methods.

[0007]

However, the neck portion 3 having a small diameter of 3 to 5 mm formed by the Dash method has a load bearing capacity of about 100 kg to 280 kg, and has a larger diameter (for example, 300 mm) and a larger weight. There is a problem that a single crystal cannot be pulled. In the method of forming a “neck” below the neck portion 3 by the Dash method,
There is a problem that this portion is wasted and a mechanism for gripping the "neck" is separately required.

SUMMARY OF THE INVENTION In view of the above-mentioned conventional problems, the present invention enhances the strength of a neck formed by the Dash method and allows a single crystal having a large diameter and a large weight to be pulled through the neck. And an apparatus.

[0009]

According to the present invention, in order to achieve the above object, a vertical magnetic field in the axial direction of a single crystal is applied to a raw material melt by a so-called necking process for growing a neck portion under a seed crystal. It is something to do. In addition, by controlling the energization of two coils of a cusp-type magnetic field generator that generates two magnetic fields in the opposite directions, a vertical magnetic field is obtained, and a single crystal body is formed after the necking process. Is a non-magnetic field or a cusp-type magnetic field is applied.

That is, according to the present invention, the seed crystal is immersed in the raw material melt in the quartz crucible and is allowed to conform, then the seed crystal is pulled up to form a neck portion, and then the single crystal body portion is formed. In the method for producing a crystal, a vertical magnetic field in the axial direction of a single crystal is applied to the raw material melt in the quartz crucible in a necking process for forming the neck portion.

Further, according to the present invention, the seed crystal is immersed in the raw material melt in the quartz crucible and allowed to adjust, then the seed crystal is pulled up to form a neck portion, and then a single crystal body portion is formed. In the method for producing a single crystal, a step of applying a vertical magnetic field in the axial direction of the single crystal to the raw material melt in the quartz crucible in a necking process for forming the neck portion, and the necking process is completed. Terminating the application of the vertical magnetic field after the formation of the upper cone portion connected to the body portion starts.

Further, according to the present invention, the seed crystal is immersed in the raw material melt in the quartz crucible and is allowed to adjust, and then the seed crystal is pulled up to form a neck portion, and then a single crystal body portion is formed. In the method for producing a single crystal, a step of applying a vertical magnetic field in the axial direction of the single crystal to the raw material melt in the quartz crucible in a necking process for forming the neck portion, and the necking process is completed. Switching the vertical magnetic field to a cusp-type magnetic field after starting the formation of the upper cone portion leading to the body part, and forming a single crystal body while applying the cusp-type magnetic field. Is provided.

Further, according to the present invention, a cusp magnetic field type single crystal manufacturing apparatus for generating a cusp type magnetic field by supplying currents in opposite directions to upper and lower coils and applying the cusp type magnetic field to a raw material melt in a quartz crucible. In the necking process of pulling up a seed crystal immersed in the raw material melt and forming a neck portion of a single crystal thereunder, current is supplied in the same direction to the upper and lower coils, and a longitudinal direction of the single crystal in the axial direction is supplied. A single crystal manufacturing apparatus is provided, which has a control means for generating a mold magnetic field and gradually stopping the supply of the current after the necking process is completed.

Further, according to the present invention, a cusp magnetic field type single crystal manufacturing apparatus for generating a cusp type magnetic field by supplying currents in opposite directions to upper and lower coils and applying the cusp type magnetic field to a raw material melt in a quartz crucible. In the necking process of pulling up a seed crystal immersed in the raw material melt and forming a neck portion of a single crystal thereunder, current is supplied in the same direction to the upper and lower coils, and a longitudinal direction of the single crystal in the axial direction is supplied. An apparatus for producing a single crystal is provided, comprising: a control means for generating a mold magnetic field and gradually supplying the reverse current after the necking process is completed.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory view showing an embodiment of a neck portion manufacturing method using a single crystal manufacturing method and apparatus according to the present invention. FIG. 2 is a configuration diagram showing a vertical magnetic field type single crystal manufacturing apparatus according to the present invention. FIG. 4 is an explanatory view showing a single crystal manufacturing process by the single crystal manufacturing apparatus of FIG. 2, FIG. 4 is a configuration diagram showing a cusp-type magnetic single crystal manufacturing apparatus according to the present invention, and FIG. It is explanatory drawing which shows a single crystal manufacturing process.

In FIG. 1, a seed crystal 1 is a seed crystal holder 5
And the seed crystal holder 5 is pulled up via the cable 6. The polycrystal is heated and melted in the quartz crucible 4, and the seed crystal 1 is immersed in the surface of the melt 2 from above, and then the seed crystal 1 is immersed in the surface of the melt 2 by thermal shock. Removal of dislocations generated in crystal 1 (elimination of dislocations)
In order to make the neck portion 3 smaller in diameter than the seed crystal 1, for example, having a diameter of 3 to 5 mm, the pulling speed is made relatively high.
(Necking process). By applying the vertical magnetic field VM to the melt 2 during the formation of the neck 3, the vibration of the melt 2 is suppressed, the unevenness on the surface of the neck 3 is reduced, and the strength is increased. In this case, since the vertical magnetic field VM is parallel to the growth axis of the single crystal, the quartz crucible 4
Thus, oxygen dissolved in the melt 2 is efficiently transported to the growth interface, so that the neck portion 3 having a high oxygen concentration is formed.

That is, although the vertical magnetic field VM is usually pointed out to disadvantages such as an increase in the oxygen concentration in the single crystal, the present invention applies the vertical magnetic field VM during the growth of the neck portion 3. This stabilizes the shape of the neck portion 3 by the Dash method and increases the mechanical strength by increasing the oxygen concentration. Here, assuming that the strength of the neck portion 3 is 1.0 when formed without a magnetic field, the strength of the neck portion 3 is approximately 1.1 when formed by applying a Cusp type magnetic field. Is approximately 1.2 when formed by applying a vertical magnetic field VM, and approximately 1.5 when formed by applying a vertical magnetic field VM. It can be increased by a factor of 1.5.

FIG. 2 shows a vertical magnetic field type single crystal manufacturing apparatus. A quartz crucible 4 in which a polycrystal is melted is disposed in a substantially cylindrical high pressure tight airtight chamber 10.
Are supported rotatably and movably in the vertical direction. The seed crystal 1 and the seed crystal holder 5 are fixed to the tip of a cable 6, and the cable 6 is wound by a winding drum 12. The take-up drum 12 is disposed in a drum unit 13, and the drum unit 13 is rotatably supported with respect to the chamber 10. A coil 11 is wound around the chamber 10 so that a vertical magnetic field VM is applied to the melt 2 in the quartz crucible 4.

Next, a manufacturing method using this vertical magnetic field type single crystal manufacturing apparatus will be described with reference to FIG. First, the inside of the chamber 10 is decompressed to about 10 torr and fresh A
While flowing r (argon) gas, the polycrystal in the quartz crucible 4 provided below in the chamber 10 is heated and melted. Then, the seed crystal 1 is melt 2 in the quartz crucible 4.
3a, and then applying a current to the coil 11 as shown in FIG.
M and the seed crystal 1
Is pulled up at a relatively high speed to form a small-diameter neck portion 3 having a diameter of 3 to 4 mm below the seed crystal 1 (necking process).

Next, as shown in FIG. 3B, at a predetermined point in time after the necking process is completed and the formation of the upper cone portion 15 is started, the application of the vertical magnetic field VM is stopped so that the coils 11a and 11b are stopped. Stop supplying current to Since a sudden change in the magnetic field strength causes irregular convection in the raw material crystal, the current value is gradually reduced to control the magnetic field strength to gradually become zero. Thereafter, the upper cone portion 15 is formed by gradually lowering the pulling speed in the absence of a magnetic field. Next, in a state of no magnetic field, the cylindrical body portion 17 is formed by pulling up at a constant speed as shown in FIG.

FIG. 4 shows a single crystal manufacturing apparatus of the cusp type magnetic field type. An upper coil 11a is wound around a chamber 10 above a quartz crucible 4, and a lower coil 11b is wound below a quartz crucible 4. Have been. According to such a configuration, by applying a current in the opposite direction to the coils 11a and 11b, it is possible to form a cusp-type magnetic field CM of a vertical magnetic field directed downward and a vertical magnetic field directed upward.

Next, a manufacturing method using this cusp type magnetic field type single crystal manufacturing apparatus will be described with reference to FIG. First, the seed crystal 1 is lowered so as to be immersed in the melt 2 in the quartz crucible 4. Then, as shown in FIG. 5 (a), currents in the same direction are applied to the coils 11a and 11b, that is, a cusp magnetic field is applied to the upper coil 11a. A vertical magnetic field VM is generated by applying a current in a direction opposite to that at the time of generation, and a necking process of pulling up the seed crystal 1 at a relatively high speed after a predetermined time elapses has a diameter of 3 mm below the seed crystal 1. ~
A neck portion 3 having a small diameter of 4 mm is formed.

Next, as shown in FIG. 5B, at a predetermined time after the necking process is completed and the formation of the upper cone portion 15 is started, the application of the vertical magnetic field VM is gradually reduced and stopped. A cusp-type magnetic field CM is formed by gradually applying currents in opposite directions to 11a and 11b.
The upper cone portion 15 is formed by gradually lowering the pulling speed in a state where the cusp type magnetic field CM is applied.
Next, in a state where the cusp type magnetic field CM is applied, the cylindrical body portion 17 is formed by pulling up at a constant speed as shown in FIG. 5C.

In the cusp-type single crystal manufacturing apparatus, during the growth of the neck portion 3 shown in FIGS. 5A and 5B, the center position of the coils 11a and 11b is set to one of the vertical directions. And a vertical magnetic field VM may be generated by applying a current only to the coil closer to the quartz crucible 4, and the growth of the body portion 17 shown in FIG. The cusp-type magnetic field CM may not be applied to the inside, and a non-magnetic field may be used. In this case, the application of the vertical magnetic field is terminated at a predetermined time after the necking process is completed and the formation of the upper cone portion 15 is started, and thereafter, the magnetic field is stopped.
The necking process is completed and the upper cone 15
The predetermined point in time after the start of the formation is selected when the diameter of the upper cone 15 becomes 10 to 90% of the diameter of the single crystal body 17. This is because the fluctuation of the magnetic field extremely near the neck portion 3 and the outer periphery 16 of the body portion 17 is not preferable.

[0025]

As described above, according to the present invention, the vertical magnetic field is applied to the melt when growing the neck under the seed crystal, so that the shape of the neck is stabilized. At the same time, the mechanical strength increases due to the high oxygen concentration. Therefore, the strength of the neck portion is strengthened, and a single crystal having a large diameter and a large weight can be pulled through the neck portion.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of a neck manufacturing method using a single crystal manufacturing method and apparatus according to the present invention.

FIG. 2 is a configuration diagram showing a vertical magnetic field type single crystal manufacturing apparatus according to the present invention.

FIG. 3 is an explanatory view showing a single crystal manufacturing process by the single crystal manufacturing apparatus of FIG.

FIG. 4 is a configuration diagram showing a cusp type magnetic field type single crystal manufacturing apparatus according to the present invention.

FIG. 5 is an explanatory view showing a single crystal manufacturing process by the single crystal manufacturing apparatus of FIG.

FIG. 6 is an explanatory view showing a conventional neck manufacturing method.

[Explanation of symbols]

 Reference Signs List 1 seed crystal 2 silicon melt 3 neck 4 quartz crucible 5 seed crystal holder 6 cable 10 chamber 11, 11a, 11b coil 15 cone 16 outer periphery of body 17 body CM cusp type magnetic field VM vertical magnetic field

Claims (7)

[Claims] 1. A method for producing a single crystal, comprising immersing a seed crystal in a raw material melt in a quartz crucible, allowing the seed crystal to blend, then pulling up the seed crystal to form a neck portion, and then forming a single crystal body portion. A single crystal manufacturing method, wherein a vertical magnetic field in the axial direction of a single crystal is applied to the raw material melt in the quartz crucible in a necking process for forming the neck portion. 2. A method for producing a single crystal, comprising immersing a seed crystal in a raw material melt in a quartz crucible, allowing the seed crystal to mix, and then pulling up the seed crystal to form a neck portion, and then forming a single crystal body portion. Applying a vertical magnetic field in the axial direction of a single crystal to the raw material melt in the quartz crucible in a necking process for forming the neck portion; and an upper portion that is completed with the necking process and is connected to a body portion of the single crystal. Ending the application of the vertical magnetic field after starting the formation of the cone portion. 3. A method for producing a single crystal in which a seed crystal is immersed in a raw material melt in a quartz crucible and is allowed to blend in, then the seed crystal is pulled up to form a neck portion, and then a single crystal body portion is formed. Applying a vertical magnetic field in the axial direction of a single crystal to the raw material melt in the quartz crucible in a necking process for forming the neck portion; and an upper portion that is completed with the necking process and is connected to a body portion of the single crystal. A step of switching the vertical magnetic field to a cusp-type magnetic field after the start of the formation of the cone part; and a step of forming a single-crystal body part while applying the cusp-type magnetic field. . 4. The method according to claim 1, further comprising the step of supplying a current in the same direction to two upper and lower coils of the cusp type magnetic field generator so as to apply the vertical magnetic field. 3. The method for producing a single crystal according to item 1. 5. The step of applying a vertical magnetic field includes the step of supplying currents in the same direction to upper and lower two coils of a cusp-type magnetic field generator, and the step of switching the vertical magnetic field to a cusp-type magnetic field. 4. The single crystal according to claim 3, further comprising a step of gradually reducing the current of one of the two coils that applies the cusp-type magnetic field to 0, and then gradually increasing the current in the direction opposite to the other coil. Production method. 6. A cusp magnetic field type single crystal manufacturing apparatus for generating a cusp-type magnetic field by supplying currents in opposite directions to upper and lower coils and applying the cusp-type magnetic field to a raw material melt in a quartz crucible, In the necking process of pulling up the seed crystal immersed in and forming a neck portion of the single crystal thereunder, a current in the same direction is supplied to the upper and lower coils to generate a vertical magnetic field in the axial direction of the single crystal, An apparatus for producing a single crystal, comprising a control means for gradually stopping the supply of the current after the necking process. 7. A cusp magnetic field type single crystal manufacturing apparatus for generating a cusp-type magnetic field by supplying currents in opposite directions to upper and lower coils and applying the cusp-type magnetic field to a raw material melt in a quartz crucible, In the necking process of pulling up the seed crystal immersed in and forming a neck portion of the single crystal thereunder, a current in the same direction is supplied to the upper and lower coils to generate a vertical magnetic field in the axial direction of the single crystal, An apparatus for producing a single crystal, comprising: a control means for gradually supplying the reverse current after the necking process.