JP2008074650A - Single crystal manufacturing apparatus and method for controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a single crystal manufacturing apparatus which can prevent a silicon single crystal being pulled from falling although a conventional Dash method comprising supporting the silicon single crystal by a neck part is used therein; and to provide a method for controlling the same. <P>SOLUTION: The single crystal manufacturing apparatus 100 is based on a Czochralski (CZ) method and equipped with a device 200 for preventing a single crystal from falling. The device 200 for preventing a single crystal from falling is provided with at least three rod-like holding tools 202 capable of being injected toward the single crystal 150 being pulled, and the holding tools 202 are arranged radially around the pulling axis of the single crystal 150. Further, the holding tools 202 are provided horizontally or in such a manner that each has an elevation angle toward the pulling axis direction of the single crystal 150 from a chamber wall. The method for controlling the single crystal manufacturing apparatus 100 is also provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a Czochralski (CZ) method for producing a single crystal and a method for controlling the single crystal production device, and in particular, a single crystal production device provided with a single crystal fall prevention device and a method for controlling the single crystal production device. About.

In the production of dislocation-free silicon single crystal by the Czochralski (CZ) method, first, a solid polycrystalline silicon raw material filled in a crucible is heated and melted by a heater arranged so as to surround the crucible. A seed crystal (seed) having a desired crystal orientation is immersed in a so-called melt that has been melted into a liquid so as to adjust to the melt temperature. When familiar, pull the seed crystal upwards. However, when the seed crystal is immersed in the melt, dislocation occurs in the seed crystal due to the temperature difference between the seed crystal and the melt. Therefore, a so-called dash method is performed to remove this dislocation.
This dash method is a method in which when the seed crystal is pulled upward, a neck portion once narrowed to a crystal diameter of about 4 mm is formed, and then expanded to a desired crystal diameter after dislocations are removed.

In recent years, the weight of a pulled silicon single crystal has increased due to an increase in the diameter of the pulled silicon single crystal and an increase in the length of the pulled single crystal accompanying an increase in the amount of solid polycrystalline silicon raw material. For example, in a φ300 mm (12 inch) single crystal that has become mainstream in recent years, the weight of the pulled single crystal may exceed 300 kg.
When an earthquake occurs during the pulling of the silicon single crystal, not only the weight of the pulled silicon single crystal but also shear stress due to twisting is applied to the neck portion narrowed by the dash method. For this reason, the silicon single crystal cannot be supported by the neck portion, and there is a possibility that the silicon single crystal being pulled is dropped due to breakage at the neck portion.
When the pulling silicon single crystal falls, not only does the pulling silicon single crystal become unusable, but also the crucible and the like, the outflow of the melt due to this, and the water vapor due to the breakdown of the cooling system. Explosions can cause serious damage.

In order to prevent such a drop of the pulled silicon single crystal that may cause serious damage, in Patent Document 1, a constricted portion is formed in a part of the silicon single crystal at the initial stage of pulling, and this constricted portion is formed. There is disclosed a means for grasping and pulling up a silicon single crystal by hooking a fingernail.
Further, Patent Document 2 discloses a means for forming an enlarged diameter portion instead of a constriction, and gripping and pulling up under the enlarged diameter portion.
Furthermore, in recent years, a so-called neckless technology has been proposed in which a dislocation-free silicon single crystal can be grown without using a neck portion by using a seed crystal having a high boron concentration so that dislocation does not occur when the seed crystal contacts the melt. (For example, Non-Patent Document 1).
Japanese Patent Publication No. 7-103000 JP-A-9-227281 T.A. Taishi et al. , Jpn. J. et al. Appl. Phys. Vol. 39 (2000) pp. L191-194 Pt. 2, no. 3A / B.

However, the method of providing the constricted portion in the silicon single crystal as in Patent Document 1 has a problem that the manufacturing cost of the silicon single crystal increases because the constricted portion cannot be used as a product. In addition, when the constriction is captured by the nail, if the plurality of claws cannot simultaneously capture the silicon single crystal, the silicon single crystal is shaken, and as a result. There is a possibility that the silicon single crystal that grows after that undergoes dislocation. The risk of dislocations due to the shaking of the silicon single crystal also exists in the method of Patent Document 2.
In the so-called neckless technology disclosed in Non-Patent Document 1, since the boron concentration of the seed crystal is high, the boron concentration on the melt side is increased by the melting of the seed crystal, and dislocation-free silicon having a desired resistivity. There is a possibility that a single crystal cannot be grown. Further, even if it is not necessary to form a neck portion by the neckless technology, there is no risk of breaking in a narrow diameter region from the seed crystal to the enlarged diameter portion.

  The present invention has been made in consideration of the above circumstances, and its purpose is to prevent the silicon single crystal from falling during pulling while using the conventional dash method that supports the silicon single crystal at the neck. An object of the present invention is to provide a single crystal manufacturing apparatus and a method for controlling the single crystal manufacturing apparatus.

An apparatus for producing a single crystal of one embodiment of the present invention,
A single crystal manufacturing apparatus using a Czochralski (CZ) method provided with a single crystal fall prevention device,
The single-crystal fall prevention device comprises three or more rod-shaped holding jigs that can be injected toward the pulled single crystal,
The holding jigs are arranged radially around the pulling axis of the single crystal,
The holding jig is provided so as to have an elevation angle horizontally or from a chamber wall toward a pulling axis direction of the single crystal.

  Here, it is desirable that a buffer mechanism using a spring is provided at an end portion of the holding jig where the single crystal contact portion is provided.

  Moreover, it is desirable that the single crystal contact portion of the holding jig is formed of a fiber reinforced material.

  Moreover, it is desirable to use a spring or hydraulic pressure as power for the injection mechanism of the holding jig.

The control method of the single crystal manufacturing apparatus of one embodiment of the present invention includes:
A control method of a single crystal manufacturing apparatus by a Czochralski (CZ) method provided with a single crystal fall prevention device,
The single-crystal fall prevention device comprises three or more rod-shaped holding jigs that can be injected toward the pulled single crystal,
The holding jigs are arranged radially around the pulling axis of the single crystal,
The holding jig is provided so as to have an elevation angle horizontally or toward the pulling axis direction of the single crystal from the chamber wall surface,
Monitor the weight of the single crystal being pulled by the weight detector,
When the amount of decrease in the single crystal weight reaches a predetermined value or more,
Injecting the holding jig,
The pulled single crystal is held.

  According to the present invention, there is provided a single crystal manufacturing apparatus and a control method for the single crystal manufacturing apparatus that can prevent the silicon single crystal from being dropped while being pulled while using the conventional dash method for supporting the silicon single crystal at the neck portion. It becomes possible.

  Hereinafter, embodiments of a single crystal manufacturing apparatus and a control method for a single crystal manufacturing apparatus according to the present invention will be described with reference to the accompanying drawings. Here, a case where a silicon single crystal is manufactured as a single crystal will be described as an example.

(Single crystal manufacturing equipment)
The single crystal manufacturing apparatus according to the present embodiment detects the fall of the silicon single crystal and prevents the fall when the neck portion of the silicon single crystal being pulled is broken due to an earthquake or the like during the pulling of the silicon single crystal. A single crystal fall prevention device is provided.

FIG. 1 is a schematic longitudinal sectional view of a single crystal manufacturing apparatus according to the present embodiment. Except for the single crystal dropping apparatus described above, the apparatus is the same as the conventionally used single crystal manufacturing apparatus.
A silicon single crystal manufacturing apparatus 100 shown in FIG. 1 heats and melts crucibles 101 and 103 filled with solid polycrystalline silicon (not shown) as a raw material and solid polycrystalline silicon to form a silicon melt 105. A main heater 107 and a lower heater 109 are housed in the chamber 111, and a pulling mechanism 141 for pulling up the grown silicon single crystal 150 is provided in the upper portion of the chamber 111. A wire 129 is unwound from a pulling mechanism 141 attached to the upper part of the chamber 111, and a seed holder (not shown) for attaching a seed crystal is connected to the tip of the wire 129. The pulling mechanism 141 is provided with a weight detector (not shown) for monitoring the load applied to the wire 129, a so-called load cell.

The crucibles 101 and 103 are composed of a quartz crucible 101 that directly accommodates the silicon melt 105 on the inside and a carbon crucible 103 for supporting the quartz crucible 101 on the outside. The crucibles 101 and 103 are supported by a crucible shaft 113 that can be rotated up and down by a rotational drive function (not shown) attached to the lower part of the silicon single crystal manufacturing apparatus.
A main heater 107 and a lower heater 109 are disposed so as to surround the crucibles 101 and 103, and the heat from the main heater 107 is prevented from being directly radiated to the chamber 111 outside the main heater 107. A first heat insulating material 115 and a second heat insulating material 117 are provided so as to surround the main heater 107. In addition, a third heat insulating material 119 and a fourth heat insulating material 121 for preventing heat from the silicon melt 105 and the crucibles 101 and 103 from being directly radiated to the chamber 111 are provided. A radiation shield 125 is provided between the silicon melt 105, the crucibles 101, 103 and the silicon single crystal 150 so that heat from the silicon melt 105 and the crucibles 101, 103 is not pulled up and hinders cooling of the silicon single crystal 150. ing. In addition, about the material of the heat insulating materials 115 and 117, it is desirable to use the thing especially excellent in heat retention property, and the shaping | molding heat insulating material is normally used. In addition, as the material of the heat insulating materials 119 and 121, for example, a molded heat insulating material, carbon, or a material in which the surface of carbon is coated with silicon carbide is used. Since the radiation shield 125 plays the role of adjusting the radiant heat, for example, a metal such as molybdenum, tungsten, or tantalum, carbon, a surface of carbon coated with silicon carbide, and a molded heat insulating material inside thereof. The installed one is used.

  The chamber 111 is made of a metal having excellent heat resistance and thermal conductivity, such as stainless steel, and is water-cooled through a cooling pipe (not shown).

  As described above, the single crystal manufacturing apparatus of the present embodiment is characterized in that the single crystal fall prevention apparatus 200 is provided. The single-crystal fall prevention device 200 includes a holding jig 202 that holds a falling silicon single crystal and an injection mechanism 204 that injects and supports the holding jig 202.

  Three or more holding jigs 202 are provided in the chamber of the single crystal manufacturing apparatus 100. This is because with two or less, it is necessary to hold the pulling-up silicon single crystal at two points, and it is extremely difficult to maintain the balance. These holding jigs 202 can be injected toward the pulled silicon single crystal 150 and have a rod shape.

  FIG. 2 is a top view showing the arrangement of the holding jig in the chamber. As shown in FIG. 2, the holding jigs 202 are arranged radially about the pulling axis of the silicon single crystal. Such a radial arrangement makes it possible to effectively hold a silicon single crystal falling by a plurality of holding jigs.

  As shown in FIG. 1, the holding jig 202 is provided horizontally or from the wall of the chamber 111 so as to have an elevation angle θ in the pulling axis direction of the silicon single crystal. This is because, when the holding jig has an inclination angle in the pulling-up axis direction of the silicon single crystal from the wall of the chamber 111, a force that accelerates the dropping of the silicon single crystal 150 works when holding the silicon single crystal 150. This is because it becomes difficult to hold the single crystal 150.

Moreover, it is desirable that the end of the holding jig on the side where the single crystal contact portion is provided is provided with a buffer mechanism using a spring. FIG. 3 is an enlarged view of a holding jig having a buffer mechanism. The holding jig 202 loaded in the injection mechanism 204 includes a holding jig main body 202a, a single crystal contact portion 202b loaded in the holding jig main body 202a, and a spring 202c provided therebetween. . By having a buffer mechanism with such a configuration, the impact by the single crystal contact portion 202b when the holding jig 202 and the silicon single crystal are in contact with each other is absorbed, and breakage / breakage at the contact portion of the crystal, It is possible to more effectively prevent damage to the single crystal manufacturing apparatus caused by breakage.
The shape of the single crystal contact portion 202b does not necessarily have to be a rod shape like the holding jig body 202a, and has a wider width than the holding jig body 202a in order to hold the silicon single crystal effectively. Even if it is planar, it may be a shape curved along the curve of the silicon side surface.

  The material of the single crystal contact portion 202b is heat resistant, has an appropriate coefficient of friction with silicon to prevent dropping, and has an appropriate elasticity to prevent destruction of the silicon single crystal, In addition, it is desirable that the silicon single crystal and the chamber are not excessively contaminated. For example, FRP (Fiber Reinforced Plastics), FRM (Fiber Reinforced Metal), FRC (Fiber Reinforced Ceramics), CC (Carbon-Carbon Composite): Carbon-Carbon Composites . In particular, from the viewpoint of heat resistance and contamination, application of a carbon-carbon composite material, a carbon fiber reinforced metal material, or a silicon carbide (SiC) fiber reinforced metal material is preferable.

  Furthermore, the holding jig main body 202a and the injection mechanism 204 in the portion exposed in the chamber not only have excellent heat resistance, but at least have a strength enough to hold a weight of 300 kg or more, which is the weight of the pulled silicon single crystal. Required. For this reason, for example, it is desirable to be formed of a SUS material.

  Then, it is desirable that the injection mechanism 204 (FIG. 1) uses a spring or hydraulic pressure as power for injecting and supporting the holding jig 202. This is because a high injection speed can be obtained and high load resistance (supportability) can be realized.

  In the single crystal manufacturing apparatus of the present embodiment, as described above, the pulling mechanism 141 (FIG. 1) includes a weight detector (not shown) that monitors the load (single crystal weight) applied to the wire 129, A so-called load cell is provided. Then, in the single crystal manufacturing apparatus of the present embodiment, when the silicon single crystal is pulled, the weight monitored by the weight detector is reduced due to the drop of the silicon single crystal, and this reduction amount becomes a predetermined value or more. In addition, a mechanism for transmitting a signal to the apparatus control system is provided. A mechanism is also provided for instructing the single crystal fall prevention device to inject the holding jig based on the transmitted signal. By these control mechanisms, it is possible to quickly and automatically inject the holding jig when the silicon single crystal falls.

Furthermore, in the single crystal manufacturing apparatus of the present embodiment, after holding the silicon single crystal falling by the holding jig, control to automatically stop the power supply to the drive system such as the heater power supply or the crucible rotation. A mechanism is also provided.
With this control mechanism, when an earthquake or the like occurs, the power supply to the single crystal manufacturing equipment can be automatically shut off without manually shutting off the power supply, preventing the occurrence of secondary disasters.・ Effects can be obtained.

(Control method for single crystal manufacturing equipment)
Next, a method for controlling the single crystal manufacturing apparatus will be described.
FIG. 4 is a diagram showing a control method sequence of the single crystal manufacturing apparatus of the present embodiment. When the pulled silicon single crystal breaks and the silicon single crystal falls, the weight detector detects the crystal breakage due to the change in weight. Then, a signal indicating the occurrence of breakage is transmitted from the weight detector and input to the apparatus control system. The device control system commands injection of the holding jig, and the dropped silicon single crystal is held by the holding jig. Thereafter, the heater power supply is automatically turned off in response to a command from the apparatus control system, and then the drive system is also stopped.

  Hereinafter, the above control method will be described in detail with reference to schematic longitudinal sectional views of the single crystal manufacturing apparatus shown in FIGS.

First, as shown in FIG. 5, a solid polycrystalline silicon raw material 155 is put into the quartz crucible 101. The seed crystal 131 is suspended from the lower end of the wire 129.
Next, after the inside of the chamber 111 and the sub-chamber 127 is replaced with an inert gas, a low pressure is maintained in a state where an inert gas such as Ar is supplied. Thereafter, by heating the heaters 107 and 109, the solid polycrystalline silicon raw material 155 previously charged in the quartz crucible 101 is melted to obtain a silicon melt 105.

  Then, as shown in FIG. 6, the seed crystal 131 suspended from the lower end of the wire 129 is lowered to just above the melt. Since the seed crystal 131 is located immediately above the silicon melt 105, it is preheated by the radiant heat of the silicon melt 105.

  Next, as shown in FIG. 7, the pulling device 141 is driven, the seed crystal 131 suspended from the lower end of the wire 129 is lowered, and at least a part of the seed crystal 131 is immersed in the silicon melt 105. Then, while pulling up the seed crystal 131, a neck portion 152 whose crystal diameter is once narrowed to about 4 mm is formed. After the dislocations are removed, the neck portion 152 is expanded to a desired crystal diameter, and the silicon single crystal 150 is gradually grown downward.

  Thereafter, as shown in FIG. 8, as the silicon single crystal 150 grows, the silicon single crystal 150 having a desired diameter and length can be pulled by pulling the wire 129 at a predetermined speed.

  Here, as shown in FIG. 9, when the neck portion 152 is broken due to an earthquake or the like during the pulling of the silicon single crystal, the silicon single crystal 152 falls due to gravity. During the pulling of the silicon single crystal, a load (single crystal weight) applied to the wire 129 is monitored by a gravity detector (not shown) provided in the pulling mechanism 141. When the silicon single crystal 152 falls and the reduction amount of the load (single crystal weight) exceeds a predetermined value, a signal transmission indicating the occurrence of breakage is automatically made and input to the device control system (not shown). The Then, the apparatus control system automatically instructs the single crystal fall prevention apparatus 200 to inject the holding jig 202. Upon receiving the command, the single crystal fall prevention device 200 automatically operates the injection mechanism 204, whereby the three holding jigs 202 are injected from three directions toward the pulling shaft of the silicon single crystal 150. In this way, the falling silicon single crystal is held, and destruction of the silicon single crystal 150 and the single crystal manufacturing apparatus 100 can be avoided.

As shown in FIG. 9, after the silicon single crystal 150 is held by the holding jig 202, the heater power supply is automatically turned off by a command from the apparatus control system, and then the drive system is also stopped.
As described above, this prevents secondary disasters.

The embodiments of the present invention have been described above with reference to specific examples. In the description of the embodiment, the description of the single crystal manufacturing apparatus, the control method of the single crystal manufacturing apparatus, etc., which is not directly necessary for the description of the present invention is omitted, but the required single crystal manufacturing apparatus. The elements related to the control method of the single crystal manufacturing apparatus can be appropriately selected and used.
In addition, all single crystal manufacturing apparatuses and control methods for single crystal manufacturing apparatuses that include elements of the present invention and can be appropriately modified by those skilled in the art are included in the scope of the present invention.

  Examples of the present invention will be described below, but the present invention is not limited by these examples.

Using the single crystal manufacturing apparatus shown in FIG. 1, the test for holding the falling silicon single crystal was repeated 10 times.
At this time, the crucible diameter was about φ550 mm, and the pulled single crystal was φ200 mm (8 inches). The silicon single crystal was dropped in a state where the single crystal was 1640 mm and weighed about 120 kg.
A holding jig made of SUS was used. And the holding jig which has the buffer mechanism by a spring shown in FIG. 3 was used. The elevation angle θ of the holding jig was 30 degrees, and the horizontal distance to the single crystal before injection of the holding jig was 1100 mm. An injection mechanism using a spring as a power was used. The material of the single crystal contact portion was a CC material. In this test, a fully automatic control mechanism as shown in the control method sequence of FIG. 4 was used.
Furthermore, for the sake of comparison, the same test was performed 10 times for a holding jig having no buffer mechanism.

As a result, when a holding jig without a buffer mechanism was used, it was not possible to hold the silicon single crystal falling only twice out of ten times. And 6 times out of 10 times, the silicon single crystal was broken from the portion where the holding jig was in contact with the silicon single crystal.
On the other hand, when a holding jig having a buffer mechanism was used, the crystal could be held without dropping 8 times out of 10 times. Of the two drops, the silicon single crystal was broken once from the portion where the holding jig was in contact with the silicon single crystal.

It is a typical longitudinal cross-sectional view of the single-crystal manufacturing apparatus of embodiment and an Example. It is a top view which shows arrangement | positioning in the chamber of the holding jig of embodiment and an Example. It is an enlarged view of the holding jig which has a buffer mechanism of an embodiment. It is a figure which shows the control method sequence of the single crystal manufacturing apparatus of embodiment and an Example. It is a typical longitudinal cross-sectional view explaining the control method of the single crystal manufacturing apparatus of embodiment. It is a typical longitudinal cross-sectional view explaining the control method of the single crystal manufacturing apparatus of embodiment. It is a typical longitudinal cross-sectional view explaining the control method of the single crystal manufacturing apparatus of embodiment. It is a typical longitudinal cross-sectional view explaining the control method of the single crystal manufacturing apparatus of embodiment. It is a typical longitudinal cross-sectional view explaining the control method of the single crystal manufacturing apparatus of embodiment.

Explanation of symbols

101 quartz crucible 105 silicon melt 111 chamber 127 sub chamber 129 wire 141 pulling mechanism 150 silicon single crystal 152 neck portion 155 solid polycrystalline silicon raw material 200 single crystal fall prevention device 202 holding jig 202a holding jig main body 202b single crystal contact Part 202c Spring 204 Injection mechanism

Claims (5)

A single crystal manufacturing apparatus using a Czochralski (CZ) method provided with a single crystal fall prevention device,
The single-crystal fall prevention device comprises three or more rod-shaped holding jigs that can be injected toward the pulled single crystal,
The holding jigs are arranged radially around the pulling axis of the single crystal,
The single crystal manufacturing apparatus, wherein the holding jig is provided so as to have an elevation angle horizontally or from a chamber wall toward a pulling axis direction of the single crystal.   The single crystal manufacturing apparatus according to claim 1, wherein a buffer mechanism using a spring is provided at an end portion of the holding jig where the single crystal contact portion is provided.   The single crystal manufacturing apparatus according to claim 1, wherein the single crystal contact portion of the holding jig is formed of a fiber reinforced material.   The single crystal manufacturing apparatus according to any one of claims 1 to 3, wherein a spring or hydraulic pressure is used as power for the injection mechanism of the holding jig. A control method of a single crystal manufacturing apparatus by a Czochralski (CZ) method provided with a single crystal fall prevention device,
The single-crystal fall prevention device comprises three or more rod-shaped holding jigs that can be injected toward the pulled single crystal,
The holding jigs are arranged radially around the pulling axis of the single crystal,
The holding jig is provided so as to have an elevation angle horizontally or toward the pulling axis direction of the single crystal from the chamber wall surface,
Monitor the weight of the single crystal being pulled by the weight detector,
When the amount of decrease in the single crystal weight reaches a predetermined value or more,
Injecting the holding jig,
A control method for a single crystal manufacturing apparatus, characterized in that the pulled single crystal is held.

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