JP2000281479A - Single crystal ingot production apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely control the temperature gradients at G1 and G2 parts in a CZ-type single crystal ingot production apparatus provided with a cooling mechanism to cool via a heat-conductive member by improving the heat- conductive member. SOLUTION: The Czochralski-type single crystal ingot production apparatus to pull up a single crystal ingot 17 from a molten raw material 12 in a furnace is provided with a heat-shielding member 18 surrounding the pulling single crystal ingot 17 and shielding the ingot from the ambient heat and a cooler 19 to cool a specific part of the pulling single crystal ingot 17. The cooler 19 has a heat-conducting member having high heat conductivity and a piping system passing a liquid refrigerant and connected to the upper part of the heat-conducting member. The heat-conducting member is composed of an anisotropic heat-conducting material to anisotropically conduct the heat from its bottom upward and the lower part of the conducting member is placed close to the part to be cooled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single crystal ingot manufacturing apparatus and method for manufacturing a single crystal ingot by the Czochralski method (hereinafter referred to as CZ method), and in particular, to a specific portion of a single crystal ingot pulled up in the apparatus TECHNICAL FIELD The present invention relates to an apparatus and a method for manufacturing a single crystal ingot provided with a cooling mechanism for cooling a steel.

[0002]

2. Description of the Related Art When a single crystal is obtained by the Czochralski method (hereinafter, CZ method), in order to control crystal defects of a single crystal ingot being pulled in a furnace (hereinafter, single crystal pulled ingot). It is said that it is effective to appropriately control the ratio "V / G" between the pulling speed V and the temperature gradient G of the single crystal pulling ingot (Japanese Patent Laid-Open No. 8-337490).

More specifically, in the case of a silicon ingot, the temperature gradient G is 1350 ° C. to 1300 ° C. from the silicon melting point called G1 (temperature gradient near the interface).
It is said that it is necessary to particularly appropriately control the area of 1150 ° C. to 1080 ° C., which is called G2 (temperature gradient of the defect formation temperature area) (Japanese Patent Laid-Open No. 10-208987). Gazette).

A single crystal ingot manufacturing apparatus in which a cooling mechanism (cooler) is provided in a furnace in order to appropriately cool such a portion has also been invented (for example, Japanese Unexamined Patent Publication No. Sho 63-163).
No. 256593, Japanese Patent No. 2562245). Furthermore, in the case of a cooler consisting of a piping system through which cooling water passes, the damage is enormous if the piping system is damaged.In consideration of this, a heat conductor is connected to the duct system through which the liquid refrigerant flows. A cooling mechanism having such a structure has also been proposed (JP-A-8-239291).

[0005]

SUMMARY OF THE INVENTION As described above,
The single crystal ingot manufacturing apparatus described in -239291 does not directly cool the single crystal pulling ingot in a piping system through which cooling water flows, but performs cooling through a solid heat conductor. Therefore, it is possible to reduce the damage when the piping is damaged and the cooling water leaks.

[0006] However, in the device described in Japanese Patent Application Laid-Open No. 8-239291, even though it has a high thermal conductivity, the decrease in cooling efficiency due to the interposition of the heat conductor is not small. There was a problem that the portions G1 and G2 could not be sufficiently cooled, and the temperature gradient in such portions could not be controlled accurately.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a CZ single crystal ingot manufacturing apparatus having a cooling mechanism for cooling via a heat conductor. Is to improve the temperature gradient of the G1 and G2 portions.

[0008]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive research and have found that "G
1 and G2), the specific portion is cooled by an anisotropic heat conductor that conducts heat anisotropically toward the “pipe system through which the cooling water flows”, whereby G1
And that the temperature gradient in the portion of G2 can be accurately controlled, and the present invention has been completed.

[0009] More specifically, the present invention provides the following.

(1) A Czochralski method single crystal ingot manufacturing apparatus for pulling a single crystal ingot from a raw material melt in a furnace, wherein the heat surrounds the pulled single crystal ingot and shields it from surrounding heat. In a Czochralski method single crystal ingot manufacturing apparatus including a shield, and a cooling mechanism for cooling a specific portion of the single crystal ingot being pulled up, the cooling mechanism includes a heat conductor having a high thermal conductivity. , A piping system through which a liquid refrigerant flows, is connected at the upper part of the heat conductor, and the heat conductor is anisotropic heat conductor that conducts heat anisotropically from the lower part to the upper part. An apparatus for producing a Czochralski single crystal ingot, comprising a body and a lower portion thereof being disposed near a portion to be cooled.

(2) In the above-mentioned Czochralski method single crystal ingot manufacturing apparatus, the anisotropic heat conductor comprises a sealed tube in which a predetermined cooling medium is sealed under reduced pressure. The cooling medium in a liquid state is vaporized at the lower portion by heat radiation from the single crystal ingot being pulled up, and the vaporized cooling medium is cooled and liquefied by the upper portion at the upper portion, falls in the sealed tube and falls again. An apparatus for producing a Czochralski single crystal ingot, wherein cooling is performed by a cycle of “vaporization”.

(3) In the above-described apparatus for manufacturing a single crystal ingot of the Czochralski method, the enclosing tube is set such that an upper portion thereof is weaker than an internal pressure than other portions. A Czochralski method single crystal ingot manufacturing apparatus, wherein a damaged cover is attached to the weak part.

(4) The apparatus for producing a Czochralski single crystal ingot according to the above description, wherein a fin receiving radiant heat generated from the pulled single crystal ingot is attached to a lower portion of the sealed tube. In addition, the above-mentioned "fin" catches radiant heat leaking from a gap between a plurality of sealing pipes attached to the device, and improves a cooling effect. May be. For example, even those attached like a fan at the bottom of the sealed tube,
It may be a screen stretched between a plurality of sealing tubes.

(5) The Czochralski single crystal ingot manufacturing apparatus as described above, wherein the liquid refrigerant in the piping system and the sealing pipe are arranged in a non-contact state with each other. In this way, even if the sealing tube ruptures, the danger that even the cooling mechanism is destroyed following the rupture is significantly reduced.

(6) In the above-described apparatus for manufacturing a Czochralski single crystal ingot, the anisotropic heat conductor is incorporated in the heat shield, and a lower end thereof is exposed to face the single crystal. An apparatus for producing a Czochralski single crystal ingot.

(7) In the above-mentioned Czochralski method single crystal ingot manufacturing apparatus, the anisotropic heat conductor contained in the heat shield is a layered graphite. Single crystal ingot manufacturing equipment.

(8) In the above-mentioned apparatus for manufacturing a single crystal ingot of the Czochralski method, the anisotropic heat conductor contained in the heat shield is a cavity having an inner wall made of a light-heat reflecting material. A Czochralski method single crystal ingot manufacturing apparatus, characterized in that: Here, the “photoreflective member” refers to an optical reflective member such as a mirror.

(9) A method for cooling a specific portion of a single crystal ingot pulled up in a Czochralski method single crystal ingot manufacturing apparatus, wherein anisotropically conducting heat from the specific portion in a predetermined direction. A method of cooling the specific portion by using an anisotropic heat conductor.

[Applicable Objects of the Present Invention] Generally, the above-mentioned temperature ranges have been reported for G1 (temperature gradient near the interface) and G2 (temperature gradient in the defect formation temperature region). It is recognized that the temperature gradient must be controlled to improve the quality of the obtained single crystal. However, the present invention relates to a case where such a site is found in addition to G1 and G2. Can also be applied to the site. That is, in the present invention, since the lower part of the cooling mechanism can be freely moved to a part to be cooled, it is extremely difficult to cool the “specific part of the pulled single crystal ingot”. Because it is easy, the target of cooling or temperature gradient control is not limited to G1 and G2,
If such a site is found in addition to G1 and G2, the present invention can be applied to such a site.

In this connection, the single crystal ingot to which the present invention is applied is not limited to a silicon ingot.
In other words, in the case of the “specific portion of the pulled single crystal ingot”, for example, in the case of G1 and G2, the temperature range as described above has been reported. The semiconductor single crystal has its own specific site. Since the specific portion can be arbitrarily measured and the position to be cooled can be determined based on the measurement result, the single crystal ingot targeted by the present invention is limited to a silicon ingot. Obviously not.

The "heat shield" is installed in the furnace to shield radiant heat from the surface of the raw material melt and heat radiation from the heater in the furnace. It also works to rectify the flow of water. Here, even if gas rectification is the main purpose, as long as the heat from the melt surface or the heater is shielded in some way,
Since it is sufficient to function as the heat shield according to the present invention, the heat shield is included in the concept of “heat shield” in the present invention, as long as the heat shield is performed in any form.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Overall Configuration] FIG. 1 is a block diagram showing a preferred embodiment of a silicon single crystal ingot manufacturing apparatus according to the present invention. FIG. 2 is a block diagram for explaining a main part of the present invention, and FIG.
FIG. 3 is an enlarged view of a main part in which a portion surrounded by A in FIG. 2 is enlarged and shows an embodiment of a damaged cover used in the present invention.

As shown in FIG. 1, a silicon single crystal ingot manufacturing apparatus according to the present invention includes a silicon melt 12 and a silicon melt 12 in a closed chamber 11 similarly to a normal CZ method silicon single crystal ingot manufacturing apparatus. Surrounding crucible 13 for production and storage and silicon ingot 17,
The heat shield 18 includes a heat shield 18 for shielding heat radiation from the silicon melt 12 and the like to the silicon ingot 17, and a cooler 19 disposed inside the heat shield 18.

The apparatus for manufacturing a silicon single crystal ingot according to the present invention also includes a heater for heating the crucible 13 and an elevation of the crucible 13 similarly to the conventional apparatus for manufacturing a silicon single crystal ingot of the CZ method. Lifting device,
Although other heat insulating materials and the like are provided, they are not shown because they are irrelevant to the essence of the present invention and are unnecessary for easily explaining the points of the present invention.

[Cooling Mechanism Using Heat Pipe] FIG.
As is apparent from the above, the features of the present invention are as follows.
That is, a so-called heat pipe is used as a part of the cooler 19. The heat pipe is `` formed of a sealed tube in which a predetermined cooling medium is sealed under reduced pressure, and in the sealed tube, `` a cooling medium in a liquid state is vaporized at a lower portion thereof by heat radiation from the single crystal ingot being pulled up. The vaporized cooling medium is cooled at the upper part by the upper part and liquefied, falls down in the sealed tube and vaporizes again. "
The cooling is performed by the cycle described above. In this embodiment, a product manufactured by Furukawa Electric Co., Ltd. is used. Further, the heat pipe 19b is shown in FIG.
Is arranged so as to surround the periphery of the silicon ingot 17, and the upper part thereof is provided with a cooling unit 19.
a. In this embodiment, the cooling unit 19a is configured by a piping system through which the cooling water flows (a piping system through which the liquid refrigerant flows).

Here, the heat pipe conducts heat very well in its length direction (about 1000 times silver).
As shown in FIG. 1B, when the heat pipe 19b is arranged to surround the periphery of the silicon ingot 17, almost no heat is transmitted in the circumferential direction of the silicon ingot 17, while Conducts heat very well. The cooling unit 19 is provided by such anisotropic heat conduction.
The heat can be efficiently transmitted to a.

Therefore, according to the apparatus for manufacturing a silicon single crystal ingot according to the present embodiment, a target location can be effectively cooled, and by this cooling effect, a specific portion of the silicon ingot 17 being pulled up can be cooled. The temperature gradient can be accurately controlled.

In addition, in the apparatus for manufacturing a silicon single crystal ingot according to this embodiment, the cooling by the cooling unit 19a is performed via the heat pipe, so that if the heat pipe 19b is ruptured, But
Since the amount of liquid contained in the heat pipe itself is extremely small, damage due to rupture can be reduced. Also, the cooling unit 1
Even if the cooling water leaks due to breakage of the piping of 9a,
Since the cooling unit 19a is located outside the furnace, damage is reduced as compared with a case where the cooler 19 is entirely formed of piping.

[Safety Mechanism] In the silicon single crystal ingot manufacturing apparatus according to the present embodiment, the heat pipe 1
As a safety measure in case of rupture of heat pipe 9b, heat pipe 19
The upper part of b is made weaker against the internal pressure than the other parts, and at the same time, the damaged cover 19c is attached to the weakened part. By doing so, in the event that the heat pipe 19b ruptures, the upper weak portion will rupture, in which case the rupture will be caught by the breakage cover 19c. So the damage is minimized.

With respect to this safety mechanism, according to this embodiment, as shown in FIG.
The structure is such that cooling is performed through the wall of the cooling jacket without making direct contact with b. By doing this,
Even if the heat pipe 19b ruptures, leakage of the liquid refrigerant in the cooling jacket can be prevented.

[Fins for Improving Cooling Effect] In the apparatus for manufacturing a silicon single crystal ingot according to the present embodiment, as shown in FIG. 4, the radiant heat from silicon ingot 17 is received below heat pipe 19b. Preferably, fins 20 are provided. Such a fin 20
Is provided, the radiant heat generated from the silicon ingot 17 is caught by the fins 20, and the caught radiant heat is transmitted to the cooling portion 19a without leakage, so that the cooling effect is provided by the provision of the fins 20. Will increase.

The upper portion of the heat pipe 19b can be made weaker than the other portions by, for example, reducing the thickness of the portion or processing the upper portion of the heat pipe 19b into a shape that is easy to burst. No. However, the method for weakening the upper portion of the heat pipe 19b is not limited to these, and any method that can be normally performed by those skilled in the art for weakening a specific portion can be adopted.

[Cooling Mechanism Using a Device Other Than a Heat Pipe] FIG. 5 is a view showing another embodiment of the Czochralski single crystal ingot manufacturing apparatus according to the present invention. In this embodiment, laminar graphite is employed as the anisotropic heat conductor, which constitutes a form incorporated in the heat shield 18. That is, according to this embodiment, the heat shield 18 is configured by sandwiching the layered graphite 18b between the thin heat insulating members 18a. Then, the lower end of the layered graphite 18b is exposed so as to face a specific portion of the silicon ingot 17,
The upper end is connected to the cooling unit 19a.

Here, since the layered graphite itself conducts heat anisotropically, if the layered graphite is configured to exhibit good heat conduction from the lower end to the upper end of the heat shield 18, the heat pipe can be used. The same effect as in the embodiment using.

FIG. 6 is a block diagram showing an embodiment in which the heat shield 18 is constituted by a pair of mirror bodies 18c having a mirror surface 18d on the inside. Also in this embodiment, the light (heat) entering from the opening 18e at the lower end of the heat shield 18 is provided.
However, the light reflected from the mirror surface 18d reaches the cooling portion 19a, and the same effect as in the above-described embodiment can be obtained.

[0036]

As described above, according to the apparatus for manufacturing a single crystal ingot according to the present invention, in the apparatus for manufacturing a single crystal ingot of the CZ method provided with a cooling mechanism for cooling via a heat conductor, By improving the portion, the desired portion of the single crystal ingot being pulled can be effectively cooled, and the temperature gradient of the portion can be controlled accurately.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a preferred embodiment of a silicon single crystal ingot manufacturing apparatus according to the present invention.

FIG. 2 is a block diagram for explaining a main part of the present invention.

FIG. 3 is an enlarged view of a main part showing an enlarged part surrounded by A in FIG. 2, and is a block diagram showing an embodiment of a damaged cover used in the present invention.

FIG. 4 is a diagram illustrating an embodiment in which fan-shaped fins are attached to a lower portion of a heat pipe.

FIG. 5 is a block diagram showing another embodiment of the present invention.

FIG. 6 is a block diagram showing still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Chamber 12 Silicon melt 13 Crucible 17 Silicon ingot 18 Heat shield 18a Thin heat insulating member 18b Layered graphite 18c Mirror surface 18d Mirror surface 18e Opening at lower end of heat shield 18 Cooler 19a Cooling unit (Piping through which cooling water flows) System) 19b Heat pipe 19c Damage cover 20 Fin

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeo Morimoto 1200 Manda, Hiratsuka-shi, Kanagawa Prefecture, Komatsu Ltd. (72) Inventor Kazuhiro Mimura 1200 Manda, Hiratsuka-shi, Kanagawa Komatsu Ltd. (72) Inventor Toshiro Kotooka 2612 Shinomiya, Hiratsuka-shi, Kanagawa F-term in Komatsu Electronic Metals Co., Ltd. 4G077 AA02 CF10 FE01 FE18

Claims (9)

[Claims] 1. A Czochralski single crystal ingot manufacturing apparatus for pulling a single crystal ingot from a raw material melt in a furnace, wherein the heat shield surrounds the pulled single crystal ingot and shields it from surrounding heat. Body, and a cooling mechanism for cooling a specific portion of the single crystal ingot being pulled up, in a Czochralski method single crystal ingot manufacturing apparatus, comprising: a heat conductor having a high thermal conductivity, And a piping system through which a liquid refrigerant flows is connected at an upper portion of the heat conductor. The heat conductor is an anisotropic heat conductor that conducts heat anisotropically from the lower portion to the upper portion. Is composed of
An apparatus for producing a Czochralski single crystal ingot, the lower part of which is arranged near a part to be cooled. 2. An apparatus for producing a Czochralski single crystal ingot according to claim 1, wherein said anisotropic heat conductor comprises a sealed tube in which a predetermined cooling medium is sealed under reduced pressure. `` The cooling medium in a liquid state is vaporized at the lower part by heat radiation from the single crystal ingot being pulled up, and the vaporized cooling medium is cooled and liquefied by the upper part at the upper part, and falls down in the sealed tube. An apparatus for producing a Czochralski single crystal ingot, wherein cooling is performed by a cycle of "vaporization again". 3. The Czochralski method single crystal ingot manufacturing apparatus according to claim 2, wherein the sealed tube is weaker at the upper portion than at other portions against pressure from inside. An apparatus for manufacturing a Czochralski single crystal ingot, which is set and has a damaged cover attached to the weak portion. 4. A Czochralski method single crystal ingot according to claim 2, wherein a fin receiving radiant heat generated from the pulled single crystal ingot is attached to a lower portion of the sealed tube. manufacturing device. 5. The Czochralski single crystal ingot manufacturing apparatus according to any one of claims 2 to 4, wherein the liquid refrigerant and the sealing pipe in the piping system are arranged in a non-contact state with each other. 6. The apparatus for manufacturing a Czochralski single crystal ingot according to claim 1, wherein the anisotropic heat conductor is built in the heat shield, and a lower end thereof is exposed to face the single crystal. A Czochralski method single crystal ingot manufacturing apparatus, comprising: 7. The Czochralski single crystal ingot manufacturing apparatus according to claim 6, wherein the anisotropic heat conductor incorporated in the heat shield is a layered graphite. Method single crystal ingot manufacturing equipment. 8. The apparatus for producing a Czochralski single crystal ingot according to claim 6, wherein the anisotropic heat conductor built in the heat shield is a cavity having an inner wall made of a light-heat reflecting material. An apparatus for producing a Czochralski single crystal ingot, comprising: 9. A method for cooling a specific portion of a single crystal ingot pulled in a Czochralski method single crystal ingot manufacturing apparatus, wherein heat is transferred anisotropically in a predetermined direction from the specific portion. A method of cooling the specific portion by using an anisotropic heat conductor.