JP2000095597A - Single crystal pulling-up device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the adverse influence of magnetic fields by arranging crucible motors for pulling up a single crystal by impressing the magnetic fields to the melt in a crucible in regions which are distant from a magnetic field generating source and where the single crystal is not affected by the magnetic fields. SOLUTION: The single crystal pulling-up device 100 has a magnet 1 which is the magnetic field generating source. The magnetic field is formed by the magnetic field generating coil 29 of the magnet 1 to control the convection of the melt in the crucible. G is 500 gauss magnetic lines of force. The magnetic field generating source 29 is movably formed and is arranged in a lower position at the time of a preparatory plan. The magnetic field generating source 29 is arranged in an upper position at the time of single crystal pulling up. The crucible is vertically driven by a crucible lifting mechanism 4 and is rotationally driven by a crucible rotating mechanism 16. The drive motors 15 and 28 of the crucible lifting mechanism 4 and the crucible rotating mechanism 16 are arranged in the regions which are distant from the magnetic field generating source 29 and where the motors are not affected by the magnetic fields, i.e., in the regions on the outer side of G of the magnetic field intensity below 500 gauss.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal pulling apparatus having a structure in which a magnetic field is applied to a melt in a crucible and a single crystal is pulled while driving the crucible by a crucible driving motor.

[0002]

2. Description of the Related Art In the Czochralski method for producing a silicon single crystal, a magnetic field is used to control the convection of a melt in a crucible (MCZ method).

[0003] In the MCZ method, a magnet (coil) for applying a magnetic field is generally movable up and down.

When pulling up a silicon single crystal, the magnet is at an upper position to control the convection of the melt. On the other hand, after pulling up the silicon single crystal, the magnet is moved to a lower position so as not to disturb the setup.

[0005] There are two types of magnetic field generating coils: a normal conducting type and a superconducting type. In the case of the superconducting type, it is necessary to cool the coil. Cooling is performed by a refrigerator using liquid helium.

[0006] It is preferable that the superconducting magnet be kept excited even when it is at the lower position. This is because when demagnetization / excitation is repeated, the consumption of liquid helium is larger than in the case where it is not.

On the other hand, the crucible is raised and lowered and rotated by a lifting mechanism and a rotating mechanism.

In the crucible elevating mechanism, a ball nut is mounted on an elevating stage guided so as to be able to elevate, a ball screw is engaged with the ball nut, and the ball screw is rotated by an elevating motor to move the elevating stage up and down. It has a configuration.

The crucible rotation mechanism is installed on a crucible lifting stage. The crucible rotation shaft is driven to rotate by a rotation motor disposed near the rotation shaft.

[0010]

In the conventional single crystal pulling apparatus, when the magnet is lowered while being excited,
The crucible drive motor was sometimes adversely affected by the influence of the magnetic field.

In order to avoid this, the magnet may be demagnetized and then lowered. In this case, however, the consumption of the cooling liquid helium increases as described above, resulting in an increase in cost and a decrease in resource saving. Met.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a single crystal pulling apparatus in which the problems of the prior art are solved and the crucible driving motor is not affected by a magnetic field.

[0013]

The object of the present invention is to generate a magnetic field from a magnetic field source, apply the magnetic field to the melt in the crucible, and pull the single crystal while driving the crucible with a crucible drive motor. A single crystal pulling apparatus having a constitution, wherein the crucible driving motor is disposed in a region far from the magnetic field generating source and unaffected by the magnetic field, for example, in a region having a magnetic field strength of 500 gauss or less. It is a lifting device.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the single crystal pulling apparatus of the present invention, a crucible driving motor is disposed in a region far from a magnetic field source and unaffected by a magnetic field, for example, in a region having a magnetic field strength of 500 gauss or less. Therefore, the crucible drive motor can drive the crucible accurately.

In a more preferred embodiment, the crucible drive motor is arranged in an area where the magnetic field strength is 200 Gauss or less, particularly 50 Gauss or less that does not affect the control panel and the like.

It is preferable that the magnetic field generating source is formed so as to be able to move up and down, and is arranged at an upper position when pulling up the single crystal and at a lower position when setting up.

The magnetic field generating source is composed of a transverse magnetic field type superconducting magnet or a caps type superconducting magnet, which can be cooled by liquid helium.

The crucible drive motor is a motor for raising and lowering the crucible and a motor for rotating the crucible.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view showing an embodiment of a single crystal pulling apparatus according to the present invention, and FIG. 2 is a schematic view of the apparatus from another angle. FIG. 3 is a perspective view showing a crucible elevating mechanism and a rotating mechanism of the single crystal pulling apparatus of FIG.

The single crystal pulling apparatus 100 includes a magnet 1 serving as a magnetic field generating source. A magnetic field is formed by the magnetic field generating coil 29 of the magnet 1 to control convection of the melt in the crucible 2. In the figure, the symbol G is 500 gauss (gauss)
s) shows the lines of magnetic force.

The magnet 1 is a transverse magnetic field type superconducting magnet, and is cooled by liquid helium. As shown in FIG. 5, the magnet 1 is lowered to a lower position A during setup, and is raised to an upper position B when pulling a single crystal.

The crucible 2 is arranged in a chamber 40 and is supported by a crucible rotating shaft 17 as shown in FIG.
However, in FIGS. 1 and 2, the crucible 2 is omitted.

The crucible 2 is driven up and down by a crucible lifting mechanism 4 and is rotated by a crucible rotating mechanism 16.

Crucible lifting mechanism 4 and crucible rotating mechanism 16
Is provided with a lifting motor (geared motor) 15 and a rotation motor (geared motor) 28,
Is set above. These drive motors 15, 28
Is located in a region outside the symbol G even in the lower position shown in FIG. 1 and FIG.
Not affected by magnetic fields.

The crucible lifting mechanism 4 includes a lifting stage 5. The elevating stage 5 is guided by two linear shafts (linear bushes) 9 so as to be slidable in the vertical direction. A ball bearing 10 is disposed in a through hole of the elevating stage 5, and a linear shaft 9 is passed therethrough. The upper and lower ends of the linear shaft 9 are
Each is fixed to the support frame.

A ball nut 7 is disposed in another through hole of the elevating stage 5, and a ball screw 6 is engaged with the ball nut 7. The bearing 8 near the lower end of the ball screw 6
Supported by the support frame. Ball screw 6
Are also supported by bearings.

A bevel gear 11b is connected to the lower end of the ball screw 6 via a short shaft.

The elevating motor 15 is connected to an extension shaft 12 having a predetermined length via a coupling 14. The extension shaft 12 is supported by two pillow blocks 13.
The length of the extension shaft 12 is such that the elevating motor 15
Set so as to be in the area of 0 Gauss or less.

A bevel gear 11a is connected to the other end of the extension shaft 12, and this bevel gear 11a meshes with a bevel gear 11b of the ball screw 6. The ball screw 6 and the extension shaft 12 form a right angle.

When the elevating motor 15 is driven, the ball screw 6 rotates, and the elevating stage 5 moves up and down together with the ball nut 7.

A crucible rotating shaft 17 is rotatably supported on the lifting stage 5 via a bearing 18. The crucible 2 is fixed to the upper end of the crucible rotation shaft 17. The crucible 2 moves up and down together with the lifting stage 5 and rotates together with the crucible rotation shaft 17. The crucible rotation shaft 17 is parallel to the linear shaft 9 and the ball screw 6.

Next to the crucible rotation shaft 17, a spline shaft 20 is supported in parallel with the spline shaft 20 so as to be rotatable at a fixed position. A spline nut 21 and a bearing 19 are arranged between the spline shaft 20 and the elevating stage 5. The elevating stage 5 includes the spline shaft 2
It can move up and down relatively to the shaft 20 while allowing zero rotation.

A bevel gear 24b is connected to the lower end of the spline shaft 20. The bevel gear 24b meshes with a bevel gear 24a attached to the extension shaft 25 of the rotation motor 28. The extension shaft 25 is also connected to an output shaft of a rotation motor 28 via a coupling 27, and is supported by two pillow blocks 26.

Spline shaft 20 and crucible rotating shaft 1
7 is rotatably connected to the belt 23 by pulleys 22a and 22b. However, this rotational connection needs to allow the crucible rotating shaft 17 to move up and down. For that purpose, for example, the pulley 22a on the spline shaft side is
What is necessary is just to support so that it may move up and down with the pulley 22b of the crucible rotation shaft 17 side. Or bearing 1
The pulleys 22a and 22b may be fixedly connected to the inner rings 9 and 18.

In this embodiment, the crucible driving motors 15, 2
Since 8 is always arranged in a region having a magnetic field intensity of 500 gauss or less, it is not necessary to demagnetize the magnetic field even during setup, and helium consumption can be suppressed to a minimum.

Further, since the drive motors 15 and 28 are located far from the crucible 2, a space can be secured around the drive motors, and maintenance is improved.

Similarly, the drive motors 15 and 28 and the crucible 2
, The influence of the vibration of the drive motor itself is reduced. Thereby, the fluctuation of the silicon melt surface can be suppressed, and the dislocation occurrence rate of the ingot can be reduced.

Next, another embodiment of the present invention will be briefly described with reference to FIG.

In this embodiment, the magnet is formed by a caps type superconducting magnet 101 having a magnetic field generating coil 129. Also in FIG. 4, the symbol G indicates a magnetic force line of 500 Gauss.

Lifting motor 15 for driving the crucible
The rotation motor 28 is also arranged in a region where the magnetic field intensity is 500 gauss or less. Therefore, the same effect as in the above-described embodiment can be obtained.

The present invention is not limited to the above embodiment. For example, a magnet mounted on a direct-cooling refrigerator that does not use liquid helium may be used. In this case, cooling energy is not required to maintain the liquid helium state because liquid helium is not used. Power consumption (energy) used for

Further, the crucible driving mechanism may be configured to transmit the torque of the driving motor to a ball screw or a spline shaft using a worm gear.

[0044]

According to the single crystal pulling apparatus of the present invention, the crucible drive motor is arranged in a region where the magnetic field strength is 500 gauss or less, so that the crucible drive motor is not adversely affected by the magnetic field, and It can be driven accurately.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a single crystal pulling apparatus according to the present invention.

FIG. 2 is a schematic view of the single crystal pulling apparatus of FIG. 1 viewed from another angle.

FIG. 3 is a perspective view showing a crucible elevating mechanism and a rotating mechanism of the single crystal pulling apparatus of FIG.

FIG. 4 is a schematic view showing another embodiment of the single crystal pulling apparatus of the present invention.

FIG. 5 is a schematic diagram for explaining a vertical movement of a magnet in the single crystal pulling apparatus of FIG. 1;

[Explanation of symbols]

 Reference Signs List 1 magnetic field source 2 crucible 15 elevating motor (crucible drive motor) 28 rotation motor (crucible drive motor) 101 magnetic field source

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akio Ima 378 Oguni-machi, Oguni-machi, Oguni-machi, Nishiokitama-gun, Yamagata F-term in the Oguni Plant of Toshiba Ceramics Co., Ltd. 4G077 AA02 BA04 CF10 EG01 EG14 EJ02 PA08 PF42 PG03

Claims (5)

[Claims] A magnetic field is generated from a magnetic field source (1; 101), the magnetic field is applied to a melt in a crucible (2), and the crucible (2) is driven by a crucible drive motor (15, 28). In a single crystal pulling apparatus configured to pull a single crystal while pulling, a crucible driving motor (15, 28) is arranged in a region far from the magnetic field generating source (1, 101) and not affected by a magnetic field. Single crystal pulling apparatus. 2. A magnetic field is generated from a magnetic field source (1, 101), the magnetic field is applied to a melt in a crucible (2), and the crucible (2) is driven by a crucible drive motor (15, 28). In a single crystal pulling apparatus configured to pull a single crystal while pulling, the crucible drive motors (15, 28) have a magnetic field strength of 500
An apparatus for pulling a single crystal, which is arranged in an area of Gauss or less. 3. A magnetic field generating source (1, 101) is formed so as to be able to move up and down, and is arranged at an upper position when pulling up a single crystal and at a lower position when setting up. The single crystal pulling apparatus as described in the above. 4. The magnetic field generating source (1, 101) comprises a transverse magnetic field type superconducting magnet (1) or a caps type superconducting magnet (101), which is cooled by liquid helium. 4. The single crystal pulling apparatus according to any one of 3. 5. A lifting motor (15) for raising and lowering a crucible (2) by a crucible drive motor (15, 28).
And a rotation motor (2) for rotating the crucible (2).
8) The method according to any one of claims 1 to 4, wherein
Item 14. The single crystal pulling apparatus according to Item 1.