JP2013043817A - Single crystal growing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a single crystal growing apparatus capable of reducing heat loss, while keeping an inner shield.SOLUTION: In this single crystal growing apparatus by Czochralski method having a main chamber for storing a crucible for storing a raw material melt, a heater arranged so as to enclose the crucible, and a shield so as to enclose the heater, the shield has a heat shield comprising a carbon fiber heat insulating material and the inner shield comprising a carbon material or a carbon fiber composite material at least on the heater side of the heat shield, and the inner shield is suspended from the ceiling of the main chamber by a support member.

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 (heat shield 108, bottom heat insulating material 111, inner wall heat insulating material 112, etc.), and the inner shield 107 receives heat from the heater 106, Since heat is released to the main chamber 102 and the like 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.

  Although different from the purpose of power saving and energy saving, Patent Document 3 discloses a method of forming protrusions in the main chamber to support the heat shield, and further holding the inner shield with 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, the heat-insulating material (heat shield) is likely to be deformed / damaged by weight load, and the carbon fiber material is likely to 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.

  On the other hand, Patent Document 4 discloses a technique for supporting a 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.

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

  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 hung from a ceiling of the main chamber by a support member.

  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, such a supporting member is not easily broken even when the inner shield is supported, and the number of parts can be reduced with a simple structure.

  Moreover, it is preferable that the said supporting member is a wire shape or a rod shape.

  With such a shape, the heat conduction path from the support member can be more narrowly limited, and the support member is more suitable for hanging the inner shield.

  Further, when the support member is in the shape of a wire, it is preferable that the inner shield is suspended through a hole provided in the upper end portion of the inner shield, or an eyebolt fixed to the upper end portion of the inner shield by screwing or bonding. In the case where the support member is rod-shaped, it is preferable that the inner shield is directly hung in a hole provided in the upper end portion of the inner shield by screwing or bonding.

  With such a structure, workability is improved even when the support member is attached or detached.

Moreover, an upper heat insulating material is further disposed on the heat shield and the inner shield.
It is preferable that the support member pass through a through hole or a notch formed in the upper heat insulating material disposed on the upper part of the shield.

  Thus, it has an upper heat insulating material, and it is possible to aim at a power saving by reducing a heat loss more by designing so that a support member may pass through the through-hole or notch.

  Furthermore, the support member is preferably made of a refractory metal or a carbon fiber material. The refractory metal is preferably Mo (molybdenum), W (tungsten), or Ti (titanium).

  Such a material is stable at a high temperature and is less likely to be destroyed during handling.

  The shield preferably includes an inner shield having a protrusion at 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. In addition, the support member as described above is not easily broken even when the inner shield is suspended, and it has a simple structure and requires a small number of parts. It 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. It is the schematic diagram which suspended the inner shield of the single-crystal growth apparatus of this invention with the wire-shaped or rod-shaped support member. It is a figure which shows an example of the top heat insulating material distribute | arranged to the shield upper part of the single crystal growth apparatus of this invention. It is a figure which shows the other example of the top heat insulating material distribute | arranged to the shield upper part of the single crystal growth apparatus of this invention.

  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 suspended the inner shield from the ceiling of the main chamber by a support member. And found that it is possible to save power by reducing heat loss, and found that such a support member has a simple structure and can be prevented from being broken due to stress concentration, thereby completing the present invention. I let you. 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. You may have the bottom part heat insulating material 11 arrange | positioned at the bottom part of 10, the inner wall heat insulating material 12 arrange | positioned at the hot water leak receiving tray 10, etc. 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 suspended from the ceiling of the main chamber 2 by the support member 14. 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, by adopting a structure in which the inner shield 7 is suspended by the support member 14, the heat conduction path is limited only to the support member 14, and a structure capable of reducing heat loss can be realized. In particular, in order to narrowly limit the heat conduction path, it is preferable that the support member has a wire shape or a rod shape. A specific embodiment is shown in FIGS.

  The material of the support member 14 is not particularly limited, and those that are stable at high temperatures are preferably applicable. In particular, the support member 14 made of a refractory metal or a carbon fiber composite material is preferable. If such a material is used, the support member 14 is stable at high temperatures and is less likely to be broken during handling. Moreover, as such a refractory metal, Mo, W, or Ti is preferable. A more preferable material is a material having a low thermal conductivity and stable at a high temperature. In that respect, glass materials and the like can be applied except that they are fragile. Any material that has low thermal conductivity and is stable at high temperatures can be used without being limited to the materials shown here. In addition, although the example of the support member 14 of three wire shapes or rod shape is drawn in FIG. 3, a number and a shape are not restricted to this.

  When the support member 14 has a wire shape, the inner shield 7 is suspended through a hole 17 provided in the upper end portion of the inner shield 7 or an eye bolt fixed to the upper end portion of the inner shield 7 by screwing or bonding. In the case where the support member 14 is rod-shaped, it is preferable that the inner shield 7 is directly hung in a hole 17 provided at the upper end portion of the inner shield 7 by screwing or bonding. With such a structure, workability is improved even when the support member 14 is attached or detached.

  Furthermore, heat loss can be further reduced by shielding the support member 14 described above with a heat insulating material. Specifically, when the upper heat insulating material 9 is further disposed on the heat shield 8 and the inner shield 7, the support member 14 is formed on the upper heat insulating material 9 as shown in FIGS. 4 and 5. It is preferable to pass through the through hole 9a (FIG. 4) or the notch 9b (FIG. 5). By designing in this way, it is possible to further reduce heat loss.

  For example, if the inner diameter of the inner shield 7 is larger than the inner diameter of the upper heat insulating material 9 of the shield 16, it is preferable to use the upper heat insulating material 9 having the through hole 9a as shown in FIG. If the inner diameter of the inner shield 7 is equal to the inner diameter of the upper heat insulating material 9, it is preferable to use the upper heat insulating material 9 having a notch 9b as shown in FIG.

  Further, as shown in FIG. 1, for example, a flange-like protrusion 15 is provided at the bottom of the inner shield 7, and the lower part of the heat shield 8 is received by this protrusion, so that the heat shield 8 is formed by the inner shield 7. It is possible to hold. 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.

  The shape of the support member 14 in the present invention is not particularly limited as long as the inner shield 7 is suspended from the ceiling of the main chamber 2. With such a shape, heat loss from the support member 14 can be suppressed, and the stress is less likely to concentrate locally on the support member 14, making it difficult to break. Examples of such a shape include a shape in which the inner shield 7 is suspended vertically from the ceiling of the main chamber 2 as shown in FIGS. Note that the number (two to about 100), the shape (round bar shape, polygonal column shape, etc.), and the thickness when the support member 14 is a wire shape or a rod shape are the weight and material of the inner shield 7 and the support member 14. Can be selected as appropriate in consideration of heat loss and the like.

  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〕
The inner shield made of carbon material is hung by a support member made of three tungsten wires as shown in FIG. 3, and an upper heat insulating material is further arranged on the upper part of the heat shield and the inner shield to provide a notch as shown in FIG. A single crystal growing apparatus as shown in FIG. 1 was prepared except that the support member was passed through the notch. At this time, the diameter of the tungsten wire was 3.5 mm, and the thickness of the inner shield was 10 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. A single crystal was grown while keeping the height of the melt surface constant to raise the liquid level to compensate for the liquid level drop.

  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 suspends the inner shield, and further reduce heat loss from the support member that passes through the heat shield and the notch of the heat insulating material disposed on the upper part of the inner shield. Since it was able to be made small, about 8% of power saving was able to be achieved 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.

  Equipped with a crucible with a diameter of 81 cm (32 inches) in the hot zone (HZ) in this single crystal growth apparatus, and with a magnetic field application Czochralski method (MCZ method), silicon with a diameter of 30 cm (12 inches) as in the examples. Single crystals were 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, 9a ... Through Hole: 9b ... Notch, 10 ... Hot water leak tray, 11 ... Bottom heat insulating material, 12 ... Inner wall heat insulating material, 14 ... Supporting member, 15 ... Projection, 16 ... Shield, 17 ... Hole, 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 Insulating material, 112 ... Insulating material on inner wall, 113 ... Supporting member, 116 ... Shield

Claims (7)

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 on the heater side of the heat shield,
The single crystal growth apparatus, wherein the inner shield is suspended from the ceiling of the main chamber by a support member.   The single crystal growing apparatus according to claim 1, wherein the support member has a wire shape or a rod shape. When the support member is in a wire shape, the inner shield is suspended through a hole provided in the upper end portion of the inner shield, or an eyebolt fixed to the upper end portion of the inner shield by screwing or bonding.
3. The single crystal growth apparatus according to claim 2, wherein, when the support member is rod-shaped, the inner shield is directly hung by a screwing type or an adhesive type in a hole provided in an upper end portion of the inner shield. . An upper heat insulating material is further disposed on top of the heat shield and the inner shield,
4. The single crystal according to claim 1, wherein the support member passes through a through hole or a notch formed in a heat insulating material disposed on the shield upper part. 5. Training device.   The single crystal growing apparatus according to any one of claims 1 to 4, wherein the support member is made of a refractory metal or a carbon fiber material.   The single crystal growth apparatus according to claim 5, wherein the refractory metal is Mo, W, or Ti. 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 6 characterized by the above-mentioned. The single crystal growing apparatus according to item.

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