JP2013053017A - Apparatus for growing single crystal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for growing a single crystal, which reduces heat loss while holding an inner shield.SOLUTION: The apparatus for growing a single crystal by a Czochralski method includes a main chamber housing a crucible accommodating a raw material melt, a heater arranged to surround the crucible, and a shield arranged to surround the heater. The shield has a heat shield formed from a carbon fiber heat insulating material and an inner shield formed from a carbon material or a carbon fiber composite material at least on the heater side of the heat shield. The inner shield is directly supported at the lower end part by a supporting member formed from a carbon fiber heat insulating material.

Description

  The present invention relates to a single crystal growing apparatus for growing a single crystal rod by the Czochralski method.

  FIG. 2 shows a schematic diagram of a conventional single crystal growth apparatus using the Czochralski method (CZ method). A conventional single crystal growing apparatus 101 includes a crucible 104 filled with a raw material melt 103 and a heater 106 disposed so as to surround the crucible 104. After the seed crystal is immersed in the raw material melt 103 in the crucible 104, the rod-shaped single crystal 105 is pulled up from the raw material melt 103. These are stored in the main chamber 102. Further, the single crystal growing apparatus 101 can include an upper heat insulating material 109, a hot water leak receiving tray 110, a bottom heat insulating material 111, and an inner wall heat insulating material 112.

  When the heat from the heater 106 is directly transmitted to the main chamber 102, the thermal loss is significant and the main chamber 102 is also damaged. Therefore, generally, a shield that blocks heat between the main chamber 102 and the heater 106. 116 is arranged. Since this shield 116 is intended to reduce heat loss, it can be used at high temperatures, and a carbon fiber heat insulating material (heat shield 108) having excellent heat insulating properties is often used.

  However, the heat shield 108 made of a carbon fiber heat insulating material is silicified in an atmosphere containing silicon vapor, and the surface becomes brittle. Of course, there is a method for suppressing silicification by coating the surface of the heat shield 108 made of carbon fiber heat insulating material, but it cannot withstand long-time use. Therefore, a structure including an inner shield 107 made of a carbon material or a carbon fiber composite material is often used at least on the heater 106 side of the heat shield 108, that is, on the atmosphere side containing silicon vapor at a high temperature. The inner shield 107 made of a carbon material or a carbon fiber composite material has a dense structure as compared with a carbon fiber heat insulating material, and has excellent silicidation resistance, so that it can be used for a long time.

  The inner shield 107 is schematically shown in Patent Document 1 and Patent Document 2, but as shown in FIG. 2, it is supported by a support member 113 and the like disposed on the hot water receiving tray 110. Even if it is not the same structure as this, it basically has a structure in contact with the main chamber 102 or the like via some structure (support member). The inner shield 107 and the support member 113 are generally made of a carbon material or a carbon fiber composite material, and are dense as described above. For this reason, the thermal conductivity of the inner shield 107 is two to three orders of magnitude higher than that of the heat insulating material (the heat shield 108, the upper heat insulating material 109, the bottom heat insulating material 111, the inner side wall heat insulating material 112, etc.). Since heat is received from the heat source and is released to the main chamber 102 through the support member 113, the structure has a problem in terms of power saving and energy saving. Further, it is necessary to prepare a complicated structure called the support member 113, and there is a problem that the number of parts increases.

  Therefore, Patent Document 3 discloses a technique for supporting the space between the inner shield and the support member with a rod-shaped member. This cuts off the heat path and reduces heat loss. This is an effective method from the viewpoint of power saving and energy saving. However, a stress in a shearing direction is applied to the portion where the inner shield is fixed to the rod-shaped member. As a result, the entire weight of the inner shield is supported by this portion, and there is a problem that stress is concentrated and the fixing portion is easily broken. In addition, as in the conventional method, there is a problem that a support member made of a carbon material is required to support the inner shield, which is complicated and increases the number of parts.

  Although different from the purposes of power saving and energy saving, Patent Document 4 discloses a method in which a protrusion is formed in a main chamber to support a heat shield, and the inner shield is held by the heat shield. If the inner shield is held using this structure, it is possible to reduce heat loss. However, this structure is not simple because it requires modification of the main chamber. In this structure, the inner shield is supported by the heat shield at a position higher than the crucible. Since the inner shield has a high specific gravity and the heat shield is a low density carbon fiber material, there is a high possibility that the heat insulating material (heat shield) will be deformed or damaged by weight load, and the carbon fiber material will be generated. The dust generated at a position higher than the crucible is highly likely to fall into the crucible, and if there is dust, there is a problem that the crystal being grown is dislocated and it is difficult to make a single crystal.

JP 2002-293691 A JP 2002-321997 A JP 2011-116600 A JP-A-10-279381

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a single crystal growth apparatus that can reduce power loss while holding an inner shield to save power.

The present invention has been made in order to solve the above-described problem, and includes a crucible for containing a raw material melt, a heater disposed so as to surround the crucible, and a shield disposed so as to surround the heater. A Czochralski method for growing a single crystal having a main chamber for storing
The shield has a heat shield made of a carbon fiber heat insulating material, and an inner shield made of a carbon material or a carbon fiber composite material at least on the heater side of the heat shield,
The inner shield is directly supported by a support member made of a carbon fiber heat insulating material at a lower end portion, and provides a single crystal growing apparatus characterized by the above.

  With such a support member, the single crystal growth apparatus can reduce power loss while holding the inner shield and can save power. In particular, by directly supporting the inner shield at the lower end, it is difficult to break, and has a simple structure and a small number of parts.

  Moreover, it is preferable that the lower end part of the said inner shield exists in a position lower than the lower end part of a crucible.

  Thereby, even when the support member is deformed and damaged by weight load, and the dust of the carbon fiber heat insulating material is generated, it is possible to prevent the dislocation of the single crystal resulting from the dust entering the crucible. .

The support member is preferably made of a carbon fiber heat insulating material having a bulk density of 0.1 g / cm ³ or more and 1.0 g / cm ³ or less.

  If it is such a bulk density, it will become a support member with which the heat insulation characteristic and intensity | strength were ensured.

Wherein the support member, a bulk density of 0.1 g / cm ³ or more 0.2 g / bulk density on the cm ³ less than the low bulk density insulation material layer 0.2 g / cm ³ or more 1.0 g / cm ³ or less of high bulk It is preferable to have a density heat insulating material layer and to directly support the inner shield by the high bulk density heat insulating material layer being in contact with the lower end portion of the inner shield.

  When the bulk density is low, the heat insulating properties are improved but the strength is weakened. When the bulk density is high, the heat insulating properties are deteriorated and the strength tends to be strong. Therefore, with such a support member, the layer in contact with the inner shield can ensure strength, and the layer not in contact with the inner shield can ensure heat insulation properties.

  Furthermore, the shield preferably includes an inner shield having a protrusion on the bottom and a heat shield held by the protrusion of the inner shield.

  With such a structure, it becomes possible to handle the heat shield and the inner shield as an integrated object, and workability is improved even when components are attached or detached.

  As described above, with the single crystal growth apparatus of the present invention, heat loss can be achieved by reducing heat loss while holding the inner shield. Further, the support member as described above is not easily broken even if the inner shield is supported, and the number of parts can be reduced with a simple structure. Moreover, intensity | strength and a heat insulation characteristic can be ensured by using the supporting member which consists of a high bulk density heat insulating material layer and a low bulk density heat insulating material layer. Furthermore, by handling the heat shield and the inner shield as an integrated object, workability at the time of attachment and removal can be improved.

It is a figure which shows an example of the single crystal growth apparatus of this invention. It is a figure which shows an example of the conventional single crystal growth apparatus.

  Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

  As a result of intensive studies on a single crystal growth apparatus that can reduce heat loss and save power while holding the inner shield, the inventors support the inner shield with a support member made of a carbon fiber heat insulating material. Thus, the present inventors have found that heat loss can be reduced and power saving can be achieved, and that such a support member can be prevented from being broken due to stress concentration, thereby completing the present invention. Hereinafter, the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a diagram showing an example of a single crystal growth apparatus of the present invention. As shown in FIG. 1, the basic structure of the CZ method single crystal growing apparatus 1 of the present invention is arranged so as to enclose a raw material melt 3 in a main chamber 2 and to surround the crucible 4. A heater 6 for heating the raw material melt 3 and a shield 16 for reducing heat loss arranged so as to surround the heater 6 are stored. Further, this single crystal growing apparatus 1 includes a heat shield 8 constituting the shield 16 and an upper heat insulating material 9 disposed on the upper part of the inner shield 7, a hot water leaking tray 10 disposed at the bottom of the main chamber 2, and a hot water leaking tray. 10 may have a bottom heat insulating material 11 arranged at the bottom of the inner wall 10, an inner wall heat insulating material arranged at the hot water leak receiving tray 10 (which can also be used as a support member as described later), and the like. After the seed crystal is immersed in the raw material melt 3 in the crucible 4, the rod-shaped single crystal 5 is pulled up from the raw material melt 3.

  The shield 16 in the present invention includes a heat shield 8 made of a carbon fiber heat insulating material that suppresses heat loss, and a carbon material or a carbon fiber composite material for suppressing deterioration of the heat insulating material at least on the heater 6 side of the heat shield 8. And an inner shield 7.

  The inner shield 7 is directly supported by a support member made of a carbon fiber heat insulating material at the lower end. The inner shield 7 is disposed around the heater 6, and the vicinity of the heater 6 is the hottest portion in the inner shield 7. When this high temperature part comes into contact with a highly heat conductive member other than the heat insulating material, heat loss increases. Therefore, supporting the inner shield 7 with a support member 14 made of a carbon fiber heat insulating material having low thermal conductivity is very effective in reducing heat loss. Moreover, the support member which consists of a carbon fiber heat insulating material of this invention can serve as the function as an inner wall heat insulating material arrange | positioned at the hot water leak tray 10 (refer the left side of FIG. 1).

  As described above, in the present invention, the lower end portion of the inner shield 7 can be uniformly supported using a large area at the upper end portion of the support member 14, so that the stress per unit area is not concentrated on a specific portion. Therefore, even if the support member is made of a carbon fiber heat insulating material, deformation and breakage can be minimized.

  In this case, the lower end portion of the inner shield 7 is preferably at a position lower than the lower end portion of the crucible 4. Since the carbon fiber heat insulating material is weaker than the carbon material or carbon fiber composite material that is the material of the inner shield 7, if the inner shield 7 is supported by the support member 14 made of the carbon fiber heat insulating material, the support member 14 is caused by a heavy load. There is a possibility that the upper part of the glass will be deformed and broken over time, and the carbon fiber heat insulating material will be generated. If this dust enters the crucible 4, the growth of the single crystal 5 is hindered, and dislocations occur, making it impossible to obtain a product. Therefore, by supporting the inner shield 7 below the crucible 4, the dust is contained in the crucible 4. Can be prevented from entering.

  In addition, as a carbon fiber heat insulating material used for the supporting member 14, the carbon fiber heat insulating material by which the surface is coated can be used. The support member 14 made of a surface-coated carbon fiber heat insulating material is not easily deformed or damaged by the weight load of the inner shield 7.

Moreover, it is preferable that the supporting member 14 consists of a carbon fiber heat insulating material with a bulk density of 0.1 g / cm ³ or more and 1.0 g / cm ³ or less. If it is such a bulk density, it will become a support member with which the heat insulation characteristic and intensity | strength were ensured.

  Further, the carbon fiber heat insulating material has a characteristic that if the bulk density is low, the heat insulating property is improved but the strength is weak, and if the bulk density is high, the heat insulating property is deteriorated and the strength is increased. Therefore, the support member 14 has a multi-layer structure made of a plurality of types of materials having different bulk densities, uses a high bulk density heat insulating material for the portion that supports the inner shield in contact with it, and uses a low bulk density carbon for the layer below it. By using a fiber heat insulating material, it becomes more resistant to deformation and breakage, and it is possible to ensure heat insulating properties.

As such a support member 14, for example, a bulk density of 0.2 g / cm ³ or more on the bulk density of 0.1 g / cm ³ or more 0.2 g / cm ³ less than the low bulk density heat insulating material layer 14 '' 1 Having a high bulk density heat insulating material layer 14 ′ of 0.0 g / cm ³ or less, wherein the high bulk density heat insulating material layer 14 ′ is in direct contact with the lower end of the inner shield 7 to directly support the inner shield 7. Is preferable (see the right side of FIG. 1). In such a support member, the layer 14 ′ in contact with the inner shield is resistant to deformation and breakage and can secure strength, and the layer 14 ″ not in contact with the inner shield can secure heat insulation properties. . It is also possible to use a carbon fiber heat insulating material whose surface is coated as described above on the layer in contact with the inner shield 7.

  Further, as shown on the right side of FIG. 1, for example, a flange-like protrusion 15 is provided on the bottom of the inner shield 7 and a structure for receiving the protrusion is formed on the heat shield 8 side, whereby the heat shield 8 is connected to the inner shield. 7 can be held. With such a structure, the heat shield 8 and the inner shield 7 can be handled as an integrated object, and workability is improved when components are attached or detached.

  EXAMPLES Hereinafter, although the Example and comparative example of this invention are given and demonstrated further in detail, this invention is not limited to the following Example.

[Example 1]
A structure in which an inner shield made of carbon material is directly supported by a support member 14 (also used as an inner wall heat insulating material) made of carbon fiber heat insulating material having a bulk density of 0.13-0.16 g / cm ³ as shown on the left side of FIG. A single crystal growth apparatus was prepared. At this time, the thickness of the inner shield was 10 mm, and the thickness of the carbon fiber heat insulating member supporting the inner shield was 140 mm.

  The raw material melt is accommodated in a crucible having a diameter of 81 cm (32 inches) in a hot zone (HZ) in this single crystal growth apparatus, and a silicon single crystal having a diameter of 30 cm (12 inches) is obtained by a magnetic field application Czochralski method (MCZ method). Nurtured. More specifically, after the seed crystal is immersed in the raw material melt in the crucible, the crucible that can be moved up and down in the direction of the crystal growth axis is crystallized during crystal growth while pulling up the rod-shaped single crystal from the melt. The temperature was raised so as to compensate for the lowering of the liquid level, and the height of the melt surface was kept constant.

  Using this single crystal growing apparatus, it was possible to grow crystals without problems. This single crystal growing apparatus can suppress heat loss from the support member that supports the inner shield, and can achieve power saving of about 10% as compared with the following comparative example.

[Example 2]
The inner shield made of carbon material, bulk density of about 1.0 g / cm ³ on the low bulk density heat insulating material layer 14 '' of FIG bulk density as shown in the right 0.13-0.16g / cm ³ A single crystal growth apparatus having a structure directly supported by a support member made of a carbon fiber heat insulating material having a high bulk density heat insulating material layer 14 'was prepared. At this time, the thickness of the inner shield was 10 mm, the height of the high bulk density heat insulating material layer was 50 mm, and the thickness of the carbon fiber heat insulating member supporting the inner shield was 140 mm.

  A hot zone (HZ) in this single crystal growing apparatus is equipped with a crucible having a diameter of 81 cm (32 inches), and a magnetic field application Czochralski method (MCZ method) is used to produce a 30 cm diameter (12 inches). A silicon single crystal was grown.

  Even when this single crystal growing apparatus was used, crystals could be grown without any problem. This single crystal growing apparatus can suppress heat loss from the support member that supports the inner shield, and can achieve power saving of about 8% as compared with the following comparative example.

[Comparative Example]
As shown in FIG. 2, a single crystal growth apparatus for supporting an inner shield made of a carbon material from below with a support member was prepared. At this time, as shown in FIG. 2, the inner shield is placed on a hot water leak receiving tray made of carbon material installed at the bottom of the main chamber, and an extended cylindrical support portion made of carbon material is placed on the inner shield. It was made the structure hold | maintained by the donut-shaped disk formed with the carbon fiber composite material on the top. At this time, the thickness of the inner shield was 10 mm, and the thickness of the support member was 15 mm. The carbon material in the support member is an isotropic graphite material, and the bulk density is about 1.8 g / cm ³ .

  A hot zone (HZ) in this single crystal growing apparatus is equipped with a crucible having a diameter of 81 cm (32 inches), and a magnetic field application Czochralski method (MCZ method) is used to produce a 30 cm diameter (12 inches). A silicon single crystal was grown.

  Even when this single crystal growing apparatus was used, crystals could be grown without any problem. However, the heat loss from the inner shield was so great that power saving could not be achieved.

  Here, silicon single crystal growth has been described as an example, but the present invention is not limited to a single crystal growth apparatus used for manufacturing a silicon single crystal, and uses a CZ method such as a compound semiconductor or an oxide single crystal. The present invention can be applied to a single crystal growing apparatus.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

DESCRIPTION OF SYMBOLS 1 ... Single crystal growth apparatus, 2 ... Main chamber, 3 ... Raw material melt, 4 ... Crucible, 5 ... Single crystal, 6 ... Heater, 7 ... Inner shield, 8 ... Heat shield, 9 ... Upper heat insulating material, 10 ... Hot water Leak tray, 11 ... bottom heat insulating material, 14 ... support member, 14 '... high bulk density heat insulating material layer, 14 "... low bulk density heat insulating material layer, 15 ... projection, 16 ... shield, 101 ... single crystal growing apparatus , 102 ... main chamber, 103 ... raw material melt, 104 ... crucible, 105 ... single crystal, 106 ... heater, 107 ... inner shield, 108 ... heat shield, 109 ... top heat insulating material, 110 ... hot water leak tray, 111 ... bottom Insulation material, 112 ... Insulation material on inner wall, 113 ... Support member, 116 ... Shield

Claims (5)

A Czochralski method single crystal growth apparatus having a main chamber for storing a crucible containing a raw material melt, a heater arranged so as to surround the crucible, and a shield arranged so as to surround the heater. And
The shield has a heat shield made of a carbon fiber heat insulating material, and an inner shield made of a carbon material or a carbon fiber composite material at least on the heater side of the heat shield,
The inner shield is directly supported by a support member made of a carbon fiber heat insulating material at a lower end portion, and the single crystal growing apparatus according to claim 1.   The single crystal growing apparatus according to claim 1, wherein a lower end portion of the inner shield is at a position lower than a lower end portion of the crucible. The single crystal growing apparatus according to claim 1, wherein the support member is made of a carbon fiber heat insulating material having a bulk density of 0.1 g / cm ³ or more and 1.0 g / cm ³ or less. . Wherein the support member, a bulk density of 0.1 g / cm ³ or more 0.2 g / bulk density on the cm ³ less than the low bulk density insulation material layer 0.2 g / cm ³ or more 1.0 g / cm ³ or less of high bulk The heat insulating material layer according to claim 1, wherein the high bulk density heat insulating material layer directly supports the inner shield by being in contact with a lower end portion of the inner shield. 4. The single crystal growth apparatus according to any one of 3 above. The said shield has the said inner shield which has a projection part in a bottom part, and the said heat shield hold | maintained by the projection part of this inner shield, The any one of Claim 1 thru | or 4 characterized by the above-mentioned. The single crystal growing apparatus according to item.

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