JPH10279389A - Method for growing single crystal, seed crystal for growing single crystal and seed crystal holder for growing single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the attainment of higher operability and shorter time for growth and to surely pull up and grow a single crystal of a large weight by eliminating the need for forming a constriction and engaging step part below a neck part and eliminating the need for clamping the single crystal from its flanks, etc., eventually eliminating the need for a high-accuracy, high- performance controller for an apparatus for growing the single crystal at the time of pulling up the single crystal of the large weight. SOLUTION: A seed crystal which is previously so formed as to have a hollow part 22H and has an annular section is used as the seed crystal so that the substantial sectional area may be assured in order for the neck part 24 formed in the lower part of the seed crystal 22 to have the sufficient tensile strength to pull up the single crystal of the large weight. The hollow neck part 24 is formed in continuation with the seed crystal 22 for the purpose of pulling up the single crystal and thereafter, the single crystal devoid of the hollow part is formed in continuation with the neck part 24 by increasing the diameter of the single crystal.

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 growth method, a single crystal growth seed crystal, and a single crystal growth seed crystal holder for producing 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 to raise the seed crystal, thereby forming a conical upper cone with the upper end protruding below the seed crystal, and a conical lower part with a cylindrical body and lower end protruding. It is configured to grow a single crystal (so-called ingot) composed of a cone portion.

[0003] In addition, in order to remove dislocations generated in the seed crystal by thermal shock when the seed crystal is immersed on the surface of the melt (to eliminate dislocations), the seed crystal is deposited on the surface of the melt. A dash (Dash) method is known in which, after immersion, a neck portion having a diameter smaller than that of a seed crystal, for example, a diameter of 3 to 4 mm is formed by increasing the pulling speed relatively high, and then the pulling of the upper cone portion is started. ing. FIG. 6 is a cross-sectional view showing a seed crystal 32 used for conventional single crystal growth and a state near a neck portion 34 formed therebelow. FIG. 6 shows a state in which the diameter of the neck portion 34 is reduced by the Dash method, and the single crystal body portion 26 is formed thereunder. Although the seed crystal 32 and the neck portion 34 are continuous crystals, the boundary between them is indicated by a dotted line for convenience. The same applies to the drawings showing each embodiment described later.

Further, through the small diameter neck portion,
Since a single crystal having a large diameter and a large weight (150 to 200 kg or more) cannot be pulled, for example, Japanese Patent Publication No. 5-654.
No. 77, by forming a small diameter neck portion by the Dash method, forming a large diameter with a relatively low pulling speed, and then forming a small diameter with a relatively high pulling speed. A method has been proposed in which a "spherical constriction" is formed, and the constriction is gripped with a gripper to pull up a large-diameter, high-weight single crystal. Further, as a conventional device for gripping the constriction, for example, there are devices disclosed in Japanese Patent Publication No. 7-103000 and Japanese Patent Publication No. 7-515, in addition to the above publications.

[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 "spherical constriction", an "annular constriction" having a larger diameter than the body portion is formed between the upper cone portion and the body portion. There has been proposed a method of gripping an “annular constriction”.

[0006]

As described above, a single crystal growing apparatus is provided so that a tensile stress due to the weight of a single crystal formed under the seed crystal is not applied to a narrow neck formed below the seed crystal. However, it was necessary to precisely control the single crystal pulling process, and it was necessary to add various high-precision and high-performance devices to the single crystal growth apparatus. For this reason, such a configuration in which a tensile stress due to the weight of the conventional single crystal is not applied has been a problem as a cause of increasing the manufacturing cost of the single crystal. In the course of crystal growth, the growing single crystal is sensitive to external vibration and easily polycrystallized, but a method for effectively preventing this has not yet been established. Furthermore, the conventional method of performing high-precision control has many control parameters,
There is also a problem that the operability of the single crystal growth apparatus is low. In addition, it takes time to form a constriction for gripping the single crystal and an engaging step, and a neck portion for protecting gripping claws for gripping the single crystal from radiant heat of the raw material melt. Need to be formed longer, which leads to a problem of prolonging the growth time, which has been a cause of a decrease in single crystal productivity.

[0007] Therefore, the present invention, when pulling a heavy single crystal, to form a constriction below the neck portion,
There is no need to form an engaging step, and there is no need for a mechanism for holding the single crystal from the side, etc. As a result, a high-precision, high-performance control device is not required for the single crystal growth apparatus, and thus operability is improved. Single crystal growth method, single crystal growth seed crystal, and single crystal growth seed crystal holder capable of achieving high growth time, shortening the growth time, and reliably pulling and growing a heavy single crystal The purpose is to provide.

[0008]

In order to achieve the above-mentioned object, the present invention provides a method for forming a neck portion below a seed crystal so that the neck portion has a sufficient tensile strength to pull a heavy single crystal. In order to ensure a large cross-sectional area, a hollow seed crystal having a circular cross section is used in advance.

That is, according to the present invention, in a single crystal growing method in which a seed crystal is immersed in a molten raw material to be immersed, and the seed crystal is pulled up to grow a single crystal, a hollow seed crystal is used as the seed crystal. A method for growing a single crystal is provided.

According to the present invention, there is also provided a single crystal growing apparatus having a chamber in which a quartz crucible is disposed, and a seed crystal raising / lowering mechanism disposed above the chamber and vertically moving a hollow seed crystal. A step of immersing the hollow seed crystal in the melt in the quartz crucible by the seed crystal raising / lowering mechanism to allow the seed crystal to conform, and pulling up the seed crystal by the seed crystal raising / lowering mechanism. Forming a hollow single crystal neck below the seed crystal, and then controlling the pulling speed by the seed crystal elevating mechanism to grow a single crystal without a hollow below the neck. Providing a single crystal growth method, comprising: increasing the diameter of the single crystal by growing the single crystal by using the seed crystal raising / lowering mechanism to grow the single crystal. It is.

Further, according to the present invention, there is provided a single crystal growth seed crystal comprising a single crystal, wherein a hollow portion is provided.

Further, according to the present invention, there is provided a single crystal growth seed crystal holder for holding a single crystal growth seed crystal during pulling up during a single crystal growth process, wherein the single crystal growth seed crystal is fitted into the recess. Wherein a communication port is provided for communicating the internal space of the recess with the outside of the single crystal growth seed crystal, and a single crystal growth seed crystal holder is provided.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a first embodiment of a single crystal growth seed crystal and a single crystal growth seed crystal holder according to the present invention used for realizing the single crystal growth method according to the present invention. FIG. 1 shows a well-known C
FIG. 3 is a cross-sectional view showing the vicinity of a seed crystal 22 and a neck portion 24 formed below the seed crystal 22 inside a single crystal growth (production) apparatus used for the Z pulling method. That is, as shown in FIG. 2, the single crystal growth apparatus 10 to which the present invention is applied is provided with a quartz crucible 14 rotated by a rotatable pedestal 16 in a pressure-resistant chamber 12 and a heater 18 for heating. A raw material melt 28 is held in the quartz crucible 14. A seed crystal holder 20 is attached to the tip of a wire 30 that can be raised and lowered by a seed crystal lifting device (not shown). The seed crystal holder 20 holds the end of the seed crystal 22 as shown in FIG.
The recess 20R is fitted and held. In FIG. 2, a heat insulator, a temperature sensor, a CCD camera for measuring the diameter of a single crystal, and the like are not shown.

As shown in the sectional view of FIG. 1, the seed crystal 22 of the present invention is hollow. That is, the line III-III in FIG.
As shown in FIG. 3 in the first embodiment, the seed crystal 22 has a cylindrical shape having a hollow portion 22H therein, and thus has a ring-shaped cross section. In FIG. 3, T is the thickness of the seed crystal 22, that is, one half of the difference between the outer diameter and the inner diameter. Such a seed crystal 22 can be manufactured by cutting out a center portion including an axis of a seed crystal made of a general columnar single crystal generally used as shown in FIG. 6 with a drill blade. In addition, the seed crystal 22 in each embodiment
Has a hollow cylindrical shape with an outer diameter of 15 mm and a thickness of 3 mm,
Any other size is free.

As shown in FIG. 1, a seed crystal holder 20 is provided.
Communication passage 20C and the recess 20 connected thereto so that the internal space of the recess 20R communicates with the outside of the seed crystal holder 20.
The opening 20E provided in R and the opening 2 provided in the side surface
0D is provided. The same pressure as the atmosphere is applied to the internal space of the seed crystal 22 via the communication path 20C. That is, the inside of the chamber 12 shown in FIG.
Although the pressure is set to about 0 Torr, when the atmosphere is not introduced into the internal space of the seed crystal 22, the neck portion 24 is crushed by the pressure applied to the outer periphery of the seed crystal 22, and the hollow portion 24H cannot be maintained in an annular shape. Therefore, the pressure difference between the inside and the outside of the seed crystal 22 and the neck portion 24 is eliminated by such a configuration. The neck 22
In order to prevent the destruction of the hollow portion 24H due to pressure from the surroundings of the seed crystal 4, the inner space 2 of the seed crystal 22 and the neck portion 24 is required.
The pressure of 2H and 24H may be slightly higher than the outside. To do so, the opening 20D of the seed crystal holder 20
The compressed argon gas can be supplied by a pump (not shown).

Next, the process of growing a single crystal according to the first embodiment will be described. The seed crystal raising / lowering mechanism that raises / lowers the seed crystal 22 can control the pulling speed manually or automatically, and can also control the power supply to the heater 18. First, the hollow seed crystal 22 is immersed in the melt 28 in the quartz crucible 14 by a seed crystal raising / lowering mechanism to be blended. Next, the seed crystal 2 is moved by the seed crystal elevating mechanism.
2 is pulled up to form a hollow single crystal neck portion 24 below the seed crystal 22. Next, in order to grow a single crystal without a hollow portion under the neck portion 24, the pulling speed by the seed crystal raising / lowering mechanism is controlled to increase the diameter of the single crystal. Next, the single crystal is pulled up by the seed crystal raising / lowering mechanism to grow the single crystal. As described above, in the present invention, by using the hollow seed crystal 22, the hollow neck portion 24 can be similarly formed below the hollow seed crystal 22, and therefore, the dislocation and the free surface of the crystal can be maintained at close positions. In addition, a necessary cross-sectional area can be secured so that the neck portion 24 has a sufficient tensile strength.

In the first embodiment shown in FIG. 1, the diameter of the neck portion 24 is narrowed down to, for example, about 3 mm as it goes downward, and is formed in a tapered shape. After the start of the so-called necking process for forming the neck portion 24, it is confirmed that the dislocations have been led out of the crystal and have disappeared. When the diameter of the single crystal is rapidly increased, the hollow portion formed in the neck portion 24 is formed. 24H is not formed on the body portion 26 of the single crystal 26. Therefore, dislocation-free single crystal growth is possible as in normal single crystal growth.

FIG. 4 is a sectional view showing a second embodiment of the present invention, and the same components as those in FIG. 1 are denoted by the same reference numerals. The seed crystal used in the second embodiment is the same as that of the first embodiment shown in FIGS. In the second embodiment, the diameter of the neck portion 24A is substantially the same as that of the first embodiment, while the neck portion 24 is gradually narrowed as shown in FIG. The difference is that the diameter of the seed crystal 22 is the same as the diameter of the seed crystal 22 and is not a tapered shape. In the second embodiment, since the diameter of the neck portion 24A is not reduced, the thickness T (FIG. 3) of the seed crystal 22 needs to be designed to be thin enough to allow dislocations to be led out of the crystal. is there. 24AH is a hollow portion of the neck portion 24A and has a constant diameter. Second
Also in the embodiment, when it is confirmed that the dislocation is led out of the crystal and disappears after the formation of the neck portion 24A, the diameter of the single crystal is sharply increased, and the neck portion 2A is formed.
The hollow portion 24AH existing at 4A is not formed in the body portion 26 of the single crystal 26. Therefore, dislocation-free single crystal growth is possible as in normal single crystal growth.

FIG. 5 is a sectional view showing a third embodiment of the present invention, and the same components as those in FIG. 2 are denoted by the same reference numerals. The seed crystal used in the third embodiment is the first and second seed crystals.
It differs from the embodiment only in the following points. That is, a communication passage is not provided in the seed crystal holder 20A, but instead is a communication port (path) 22 for communicating the inside and the outside of the seed crystal 22A itself.
C is provided. The operation of the communication port 22C is the same as in the first and second embodiments, and the above-described pressurizing pump can be connected as necessary. In the third embodiment, the neck 2
4A, similar to the second embodiment, shows an example in which the diameter of the seed crystal 22 is substantially the same as that of the seed crystal 22 and is not tapered. Thereby, it can be made into a tapered shape as shown in FIG.

In the above embodiment, the seed crystal has a cylindrical shape as an example. However, a hollow polygonal column-shaped seed crystal having a polygonal cross section may be used.

[0021]

As described above, according to the present invention, a hollow neck portion is formed below a hollow seed crystal, and a single crystal body portion is formed below the neck portion. Therefore, the following effects are obtained. First, when pulling a heavy single crystal, it is not necessary to form a constriction below the neck or to form an engagement step, so the process is simplified, the growth time is shortened, and the cost is reduced. It is possible. Further, since a mechanism for mechanically holding the single crystal from a side surface or the like is not required, it is possible to contribute to the cost reduction of the single crystal growth apparatus, and as a result, it is possible to reduce the manufacturing cost of the single crystal itself. Further, since such a gripping mechanism is not required, a step of forming a long neck portion for protecting the claw portion of the gripping mechanism from the radiant heat of the raw material melt is unnecessary, and the growth time can be shortened. it can.

Further, since the gripping mechanism is not used, polycrystallization of the single crystal due to the member of the gripping mechanism touching the single crystal can be suppressed. In addition, 150-200kg
High-precision, high-performance control using many control parameters, which was conventionally required, is not necessary for pulling a single crystal with a heavy weight exceeding 100 kg. Only a certain degree of control device and operation is required, and trouble during operation can be reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a single crystal growth seed crystal and a single crystal growth seed crystal holder according to the present invention used to realize a first embodiment of a single crystal growth method according to the present invention.

FIG. 2 is a schematic sectional view of a single crystal growing apparatus to which the present invention is applied.

FIG. 3 shows a seed crystal according to the first embodiment in FIG.
FIG. 3 is a cross-sectional view when cut along III-III.

FIG. 4 is a sectional view showing a second embodiment of the single crystal growth method according to the present invention.

FIG. 5 is a cross-sectional view showing a seed crystal for growing a single crystal according to the present invention, which is used for realizing a third embodiment of the single crystal growing method according to the present invention.

FIG. 6 is a sectional view showing the vicinity of a seed crystal and a neck used in a conventional single crystal growth method and apparatus.

[Explanation of symbols]

 Reference Signs List 10 single crystal growth (manufacturing) apparatus 12 pressure-resistant chamber 14 quartz crucible 16 pedestal 18 heater 20, 20A seed crystal holder 20C communication passage 20D, 20E opening 20R recess 22 seed crystal 22C communication opening 22H, 24H, 24AH hollow part 24, 24A neck Part 26 Body part 28 Raw material melt 30 Wire T Seed crystal thickness

Claims (10)

[Claims] 1. A single crystal growing method in which a seed crystal is immersed in a molten raw material to be immersed therein, and the seed crystal is pulled up to grow a single crystal, wherein a hollow seed crystal is used as the seed crystal. Single crystal growth method. 2. The method of growing a single crystal according to claim 1, further comprising the step of continuously forming a hollow neck portion having a smaller diameter as going downward from the seed crystal. 3. The method of growing a single crystal according to claim 1, further comprising the step of forming a hollow neck portion having substantially the same diameter as the diameter of the seed crystal, following the seed crystal. 4. A step of forming a hollow neck portion continuously with the seed crystal, and thereafter increasing a diameter of the single crystal to continuously form a single crystal without a hollow portion in the neck portion. The single crystal growth method according to claim 1, further comprising: 5. A single crystal using a single crystal growth apparatus having a chamber in which a quartz crucible is disposed, and a seed crystal raising / lowering mechanism disposed above the chamber and vertically moving a hollow seed crystal. A growing method, wherein the hollow seed crystal is immersed in the melt in the quartz crucible by the seed crystal raising / lowering mechanism to be blended, and the seed crystal is pulled up by the seed crystal raising / lowering mechanism. Forming a neck portion of a hollow single crystal below, and then controlling a pulling speed by the seed crystal raising / lowering mechanism to grow a single crystal having no hollow portion under the neck portion. A single crystal growth method, comprising: increasing a diameter; and growing the single crystal by pulling up the single crystal by the seed crystal raising / lowering mechanism. 6. A single crystal growth seed crystal comprising a single crystal, wherein a hollow portion is provided in the single crystal growth seed crystal. 7. The thickness of the single crystal growth seed crystal is small enough to allow dislocations to be led out of the crystal when the single crystal growth seed crystal is used to grow a neck portion of the single crystal. 7. The seed crystal for growing a single crystal according to claim 6, wherein the seed crystal has a thickness. 8. The single crystal growth seed crystal according to claim 6, wherein the single crystal growth seed crystal has a cylindrical shape or a hollow polygonal column shape. 9. The single crystal growth according to claim 6, wherein a communication port is provided in the single crystal growth seed crystal to allow communication between the inside and the outside of the hollow portion. Seed crystal. 10. A single crystal growth seed crystal holder for holding a single crystal growth seed crystal at the time of pulling up a single crystal growth process, wherein said single crystal growth seed crystal has a concave portion into which said single crystal growth seed crystal is fitted. A single crystal growth seed crystal holder, wherein a communication port is provided for communicating an internal space of the recess with the outside of the single crystal growth seed crystal.