JP4036615B2 - Single crystal growth equipment - Google Patents

Description

【Technical field】
[0001]
The present invention relates to a single crystal growth apparatus for producing a dislocation-free single crystal of Si (silicon) by a pulling CZ (Czochralski) method.
[Background]
[0002]
In general, in a single crystal growth apparatus or single crystal pulling apparatus based on the pulling CZ method, the inside of the high pressure-resistant airtight chamber is decompressed to about 10 torr and a fresh Ar (argon) gas is allowed to flow, and a quartz crucible provided below the chamber is provided. The inner polycrystal is heated and melted, and the seed crystal is immersed on the surface of the melt from above, and the seed crystal is pulled up while rotating and moving the seed crystal and the quartz crucible up and down, so that the upper end below the seed crystal. It is configured to grow a single crystal rod (so-called ingot) composed of a conical upper cone part projecting from a cylindrical body part (straight body part) and a conical lower cone part projecting from the lower end. .
[0003]
Also, as this growth method, after removing the seed crystal on the surface of the melt in order to remove dislocations generated in the seed crystal due to thermal shock when the seed crystal is immersed in the surface of the melt (no dislocation) A Dash method is known in which the upper cone portion starts to be lifted after a neck portion having a diameter smaller than that of the seed crystal, for example, a diameter of 3 to 4 mm, is formed by relatively increasing the pulling speed. .
[0004]
Furthermore, since a single crystal having a large diameter and a large weight (150 to 200 kg or more) cannot be pulled up through the small diameter neck portion, for example, as shown in Japanese Examined Patent Publication No. 5-65477, the small diameter is obtained by the Dash method. After forming the neck part, the pulling speed is relatively slow to form a large diameter, and then the pulling speed is relatively fast to form a small diameter to form a “spherical diameter enlarged part”. There has been proposed a method of pulling up a large-diameter, heavy-weight single crystal by gripping the enlarged portion with a gripper. In addition to the above publications, conventional apparatuses for gripping the diameter-enlarged portion include those shown in, for example, Japanese Patent Publication Nos. 7-103000 and 7-515.
[0005]
As other conventional examples, for example, as shown in JP-A-5-270974 and JP-A-7-172981, there is a method of holding the body part as it is without forming the “diameter enlarged part”, As disclosed in Japanese Laid-Open Patent Publication No. 63-252991 and Japanese Patent Laid-Open No. 5-270975, instead of the above “spherical diameter enlarged portion”, a “annular shape” having a diameter larger than that of the body portion between the upper cone portion and the body portion. A method of forming a “diameter enlarged portion” and gripping the “annular diameter enlarged portion” has been proposed. In such a conventional method, a holding member whose tip can be opened and closed is used to hold the lower end of the enlarged diameter portion of the single crystal formed below the enlarged diameter portion formed below the seed crystal. As such a gripping member, a metal member such as molybdenum is used because it needs to have a predetermined strength at a high temperature.
[0006]
However, a metal member generally has high hardness, and when a load is applied in contact with the protrusions of the single crystal habit line, the habit line is damaged and a single crystal dislocation problem is likely to occur. Therefore, it is conceivable to use a carbon fiber reinforced carbon composite material (carbon composite material: also referred to as C / C material) that is softer than metal. The carbon fiber reinforced carbon composite material is a carbon-bonded carbon fiber. Specifically, the carbon fiber is laminated in multiple layers, or the wound material is coated and impregnated with resin or coal pitch. Or carbon pitch of carbon pitch and carbon bond. Examples of using such a carbon fiber reinforced carbon composite material in a quartz crucible protective container of a single crystal growth apparatus are disclosed in, for example, Japanese Patent Application Laid-Open Nos. 10-72291 and 10-139581, but are reinforced with carbon fiber. The use of the carbon composite material for the contact portion of the gripping member with the single crystal is not what has been known in the past, but the present inventor has come up with in the process of completing the present invention. Since the carbon fiber reinforced carbon composite material is formed by weaving carbon fibers to form a plurality of layers, when a large load is applied to a part of the member made of such a material, the load is applied to the other part of the member. A rotational moment may be applied to the substrate, and as a result, a force in the direction of peeling the plurality of layers may be applied. In recent years, the diameter of a single crystal grown by a single crystal growth apparatus tends to increase, but considering the case of a silicon single crystal whose weight of a single crystal to be pulled is about 400 kg, a carbon fiber reinforced carbon composite material is When the grip portion is used in a contact portion with a single crystal, peeling may occur between the layers, and if a load is applied, tearing may occur.
DISCLOSURE OF THE INVENTION
[0007]
In view of the problems in the case where the conventional metal gripping member or the carbon fiber reinforced carbon composite material is used for a contact portion with a single crystal, the present invention is provided for the diameter-enlarged portion of the single crystal constituted by the CZ method. Even if the load of the single crystal to be pulled is a large weight of about 400 kg without causing damage to the crystal habit line of the single crystal at the contact portion with the single crystal of the gripping member that grips the lower end, A single crystal growth apparatus that can be pulled up by arranging members that do not cause peeling, growing such a large weight, large diameter single crystal rod in a stable state and without causing dislocation due to damage to the habit line. The purpose is to provide.
[0008]
In order to achieve the above object, in the present invention, heat is applied to the surface of the carbon fiber reinforced carbon composite material at the contact portion with the single crystal of the holding member that holds the lower end of the enlarged diameter portion of the single crystal formed below the seed crystal. A cracked carbon film is formed, and a contact member having a surface hardness of 70 or more in Shore hardness and 100 or less in Vickers hardness is provided.
[0009]
That is, according to the present invention, a chamber in which a quartz crucible is arranged, a seed crystal lifting mechanism for raising and lowering a seed crystal in the vertical direction above the quartz crucible, and a movable in the vertical direction in the chamber are arranged. The seed crystal lifting mechanism forms a neck portion of the single crystal under the seed crystal by immersing the seed crystal in the melt in the quartz crucible and pulling it up. The single crystal holding member is used to form a diameter-enlarged portion of the single crystal under the neck portion, and the single-crystal holding member is lifted by holding the diameter-increased portion from below after the diameter-enlarged portion of the single crystal is formed. In the single crystal growth apparatus configured to be used for pulling up the single crystal , heat is applied to the surface of the carbon fiber reinforced carbon composite material at the portion of the gripping member that contacts the lower end of the diameter enlarged portion of the single crystal. Disassembly In over 70 hardness Shore hardness of the surface portion be those coatings to the formation of hydrogen, single-crystal growth apparatus are provided, characterized in that it arranged contact member 100 or less in Vickers hardness.
[0010]
As the contact member that contacts the single crystal, a carbon fiber reinforced carbon composite material having a pyrolytic carbon film formed on the surface thereof can be suitably used. It is a preferable aspect of the present invention that the coating is thin enough to cover the inside of the fine dent on the surface of the carbon fiber reinforced carbon composite material. Moreover, it is a preferable aspect of the present invention that the coating film is formed by a method of permeating and depositing the pyrolytic carbon. Furthermore, it is a preferable aspect of the present invention that the single crystal gripping member has a member that can move between a first position deviated from below the enlarged diameter portion and a second position below the enlarged diameter portion. . Moreover, it is a preferable aspect of the present invention that the movable member can be rotated in a plane substantially perpendicular to the pulling direction of the single crystal. Moreover, it is a preferable aspect of the present invention that the single crystal holding member has a plurality of movable members arranged so as to surround the enlarged diameter portion. Moreover, it is a preferable aspect of the present invention that the contact member has a curved dent for stably holding the enlarged diameter portion.
BEST MODE FOR CARRYING OUT THE INVENTION
[0011]
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing an embodiment of a single crystal pulling apparatus according to the present invention. In FIG. 1, a quartz crucible 10 is rotatably mounted by a pedestal 11 in a vacuum chamber 18 that is also a casing of a single crystal growth apparatus. A pulling shaft (wire) 1 is attached to the upper part of the quartz crucible 10 in a state in which it can be raised and lowered by a lifting mechanism (not shown). A seed crystal holder 2 is attached to the tip of the pulling shaft 1, and a seed crystal 3 is attached to the seed crystal holder 2. FIG. 1 shows that a seed crystal 3 is attached to a polycrystalline melt 12 in a quartz crucible 10 at one end, and then pulled up to form a dash neck, and then a spherical diameter enlarged portion (bicorn) 4 of a single crystal rod 7 is formed. Then, after the constriction 5 is formed, the upper cone portion 7A and the straight body portion 7B are formed.
[0012]
Under the enlarged diameter portion 4, the tip portions of the two gripping members 8A and 8B can be inserted. That is, the tip portions of the two gripping members 8A and 8B are movable in the direction perpendicular to the pulling direction of the single crystal rod 7 (the direction perpendicular to the direction of the shaft 1 in FIG. 1) as indicated by the arrow M1. The diameter enlarged portion 4 is formed by a known method, that is, by controlling the pulling speed or the like. Until the diameter enlarged portion 4 is provided, the distal ends of the two gripping members 8A and 8B are radially outward from the position in FIG. When the diameter enlarged portion 4 is formed, it is moved to the position of FIG. 1 (second position). The two gripping members 8A and 8B can be rotated in synchronism with the seed crystal 3 by a rotation / lifting mechanism (not shown) and can be lifted / lowered by a mechanism separate from the lifting / lowering mechanism of the shaft 1 or a partly common mechanism. The diameter enlarged portion 4 is gripped from below the diameter enlarged portion 4.
[0013]
Contact members 9 </ b> A and 9 </ b> B are provided at contact portions of the gripping members 8 </ b> A and 8 </ b> B that grip the lower end of the diameter-enlarged portion 4 with the diameter-enlarged portion 4, respectively. As shown in FIG. 2, the contact members 9A and 9B are attached in the vicinity of the tips of the gripping members 8A and 8B, and a curved recess 9C is formed so as to stably hold the lower end of the enlarged diameter portion 4 from below. Yes. Contact members 9A, 9B, the hardness of the surface portion is more than 70 in Shore hardness, composed of Der Ru material 100 below a Vickers hardness. As the member having such physical properties, a member obtained by forming a pyrolytic carbon film on the surface of a carbon fiber reinforced carbon composite material can be used. In addition, it is preferable that the thickness is thin so that this film can cover the inside of the fine dent on the surface of the carbon fiber reinforced carbon composite material. This film is formed by a method in which pyrolytic carbon is permeated and deposited, and can be constituted, for example, by the CVI method described in JP-A-9-295889.
[0014]
The contact members 9A, 9B is the hardness of the surface portion as described above over 70 in Shore hardness, is constructed of a material is 100 or less in Vickers hardness, heat on the surface of the carbon fiber reinforced carbon composite material Not only those having a cracked carbon film formed but also other materials satisfying these hardness and tensile strength can be suitably used . Although the upper Symbol hardness is defined by the Shore hardness and Vickers hardness, which is for the following reason. Shore hardness (shore) indicates rebound hardness, while Vickers hardness indicates indentation hardness (Latis Co., Ltd. issued: “Units” Dictionary revision 4th edition "p51). These two hardnesses do not necessarily correspond to each other, but can be selectively used depending on the purpose and method of measurement.
[0015]
As can be seen from the above, the hardness of the surface portion being 70 or more in Shore hardness indicates that the rebound hardness is a certain value or more, while the hardness of the surface portion is 100 or less in Vickers hardness. This means that the indentation hardness is below a certain value. By having such characteristics, when a load from the enlarged diameter portion 4 is applied to the contact members 9A and 9B, the contact members 9A and 9B do not adversely affect the crystal habit line of the single crystal in the enlarged diameter portion, and Even if the load of the single crystal rod 7 is as large as about 400 kg, it shows sufficient strength. That is, if the contact members 9A and 9B have a certain degree of hardness, the surface is slightly recessed when a load is applied, so stress concentration is difficult to occur, but if it is too hard, the surface is almost recessed. However, the stress concentrates on the habit line portion of the single crystal, and the single crystal itself is easily broken. Note that if the contact members 9A and 9B are too soft, deformation occurs. Therefore, when the diameter enlarged portion 4 is supported from below, the diameter enlarged portion 4 temporarily falls downward, which is extremely undesirable in terms of crystal growth.
[0016]
An experiment was conducted to evaluate the influence of the surface hardness of the contact members 9A and 9B. First, as shown in FIG. 4, silicon (Si) as a test material is prepared as a rod-shaped member 20 having diameter enlarged portions 20A and 20B in the vicinity of both ends, and these diameter enlarged portions 20A and 20B are prepared as shown in FIG. The test was carried out by engaging with a tensile test hand 26 shown in FIG. 5 and pulling in both directions as indicated by an arrow M2 in FIG. The tensile test hand 26 has a structure in which a holder member 24 that is in contact with the enlarged diameter portions 20A and 20B and is loaded can be attached. When the holder member 24 is made of (1) the same material as that used for the contact members 9A and 9B, that is, a member made of a surface-treated carbon fiber reinforced carbon composite material, (2) surface treatment is performed. When no carbon fiber reinforced carbon composite material was used, (3) three types of cases where a member made of SUS was used were tested.
[0017]
The results of the experiment are shown in the displacement-load curve graph of FIG. When the member made of SUS (3) was used, the load was about 4.7 kN, and the single crystal material to be tested was broken. The state of this fracture is shown in the photograph of FIG. When the carbon fiber reinforced carbon composite material not subjected to the surface treatment of (2) was used, a maximum load resistance of 5.9 kN was obtained. In this experiment, the single crystal material to be tested did not break. When a member made of the same material as that used for the contact members 9A and 9B in the embodiment of (1) was used, a maximum load capacity of 14.92 kN was obtained. In this case, the photograph of FIG. 8 shows the single crystal habit line biting into the surface of the holder member 24. In this experiment as well, as in (2), the single crystal material to be tested did not break. FIG. 9 is a photograph of the holder member 24 after a tensile test using the holder member 24 made of SUS having the shape shown in FIG. 4 as a comparative example and surface-treated in the same manner as (1) above. is there. As can be seen from the comparison between FIG. 8 and FIG. 9, in the case of the SUS test material shown in FIG. 9, no trace of biting is seen in the holder member 24 made of the surface-treated carbon fiber reinforced carbon composite material.
[0018]
In the graph of FIG. 6, when a member made of the same material as that used for the contact members 9 </ b> A and 9 </ b> B in the embodiment of (1) is used, when the displacement is further past the peak of the displacement-load curve, Delamination occurs inside the holder member 24. This is shown in the photograph of FIG. It has been confirmed that such delamination did not occur until the peak of the displacement-load curve was reached. As can be seen from the above experiment, when the holder member (1), that is, the surface-treated carbon fiber reinforced carbon composite material is used, the maximum load capacity reaches 14.92 kN, and the total number of single crystal rods 7 to be pulled up is increased. When the weight is 400 kg, it is understood that the value is almost three times as large as 4.00 kN. That is, in the single crystal growth apparatus of the present invention, the above-mentioned member is used for the contact members 9A and 9B of the gripping portion in FIG.
[0019]
The surface-treated carbon fiber reinforced carbon composite material is a hardness Shore hardness of the surface portion 70 above, Ru Der 100 or less in Vickers hardness, a single crystal of the gripping members for gripping the enlarged-diameter portion 4 of such member ( By using it as a contact portion with the enlarged diameter portion 4), it is excellent in heat resistance and load resistance, can be pulled up stably without dislocation.
[0020]
In the above embodiment, the gripping members 8A and 8B are arm-shaped and are composed of two members that can be opened and closed in a direction perpendicular to the pulling direction. However, the present invention is not limited to such a gripping member, and FIG. The holding members 8A and 8B can be configured to be rotatable in a plane substantially perpendicular to the pulling direction of the single crystal rod 7. That is, at a certain rotation angle, the contact members 9 </ b> A and 9 </ b> B are located at a position deviated from the lower side of the enlarged diameter portion 4, and can be configured to be located below the enlarged diameter portion 4 when the angle changes by rotating. . The present invention can also be applied to a structure in which a dish-shaped member having a slit in the gripping member is applied from below the enlarged diameter portion. That is, even if the gripping member or the gripping mechanism is structurally different from that shown in the above embodiment, the diameter-enlarged portion (bicorn) formed above the single crystal upper cone portion 7A is supported from below. Thus, the contact member can be disposed at the contact portion of any gripping member to be gripped with the single crystal.
[Industrial applicability]
[0021]
As described above, according to the present invention, the hardness of the surface portion of the single crystal formed under the seed crystal contacts the lower end of the enlarged diameter portion of the holding member that holds the enlarged diameter portion of the single crystal from below. Since a member having a hardness of 70 or more and a Vickers hardness of 100 or less is arranged, a large-sized single crystal rod having excellent load resistance and a total weight of 400 kg is pulled up without dislocation and stably growing. be able to.
[Brief description of the drawings]
[0022]
FIG. 1 is a partial sectional view schematically showing a preferred embodiment of a single crystal growth apparatus according to the present invention.
FIG. 2 is a cross-sectional view showing the vicinity of the tip of the gripping member in FIG.
3 is a perspective view of a contact member attached in the vicinity of the front end of the gripping member shown in FIG. 2. FIG.
FIG. 4 is a plan view of a material under test used in an experiment for clarifying the effects of the present invention.
5 is a schematic diagram showing a state in which the material to be tested of FIG. 4 is mounted on a tensile test band used in an experiment for clarifying the effect of the present invention.
FIG. 6 is a displacement-load curve graph showing a result of an experiment for clarifying the effect of the present invention.
FIG. 7 is a photograph showing a material under test broken in an experiment for clarifying the effect of the present invention.
FIG. 8 is a photograph showing a state in which a single crystal habit line bites into a holder member made of a carbon fiber-reinforced carbon composite material that has been surface-treated in an experiment for clarifying the effect of the present invention.
FIG. 9 shows, as a comparative example in an experiment for clarifying the effect of the present invention, when a material to be tested made of SUS is used, the holder member made of a surface-treated carbon fiber reinforced carbon composite material has a single crystal crystal. It is a photograph showing a state in which the shoreline does not penetrate.
FIG. 10 shows the inside of the holder member when the holder member made of the same material as that used in the present invention in the experiment for clarifying the effect of the present invention is further displaced beyond the peak of the displacement-load curve. It is a photograph of a section showing signs that delamination occurs.
[Explanation of symbols]
[0023]
In addition, the legend of the code | symbol in drawing is as follows.
DESCRIPTION OF SYMBOLS 1 Pulling shaft 2 Seed crystal holder 3 Seed crystal 4 Diameter enlarged part 5 Constriction part 7 Single crystal rod 7A Upper cone part 7B Straight body part 8A, 8B Holding member 9A, 9B Contact member 9C Recess 10 Quartz crucible 11 Pedestal 12 Polycrystalline melting Liquid 18 Vacuum chamber

Claims (7)

A chamber in which a quartz crucible is placed;
A seed crystal ascending / descending mechanism for vertically moving the seed crystal above and above the quartz crucible; and a single crystal gripping member disposed so as to be movable in the vertical direction within the chamber. Used to form a single crystal neck under the seed crystal by immersing the crystal in a melt in the quartz crucible and pulling it up, and then forming a single crystal diameter enlarged portion under the neck. The single crystal gripping member is configured to be used for pulling up the single crystal by gripping and lifting the diameter enlarged portion from below after the diameter enlarged portion of the single crystal is formed. The pyrolytic carbon coating is formed on the surface of the carbon fiber reinforced carbon composite material at the portion of the gripping member that contacts the lower end of the diameter-enlarged portion of the single crystal, and the hardness of the surface portion is Shore hardness 70 or more In a single crystal growth apparatus is characterized in that arranged contact member 100 or less in Vickers hardness. It said coating is a single crystal growth apparatus according to claim 1, wherein those formed by a method of infiltrating deposit the pyrolytic carbon.   2. The single crystal growth according to claim 1, wherein the single crystal gripping member has a member movable between a first position deviated from a lower side of the enlarged diameter portion and a second position below the enlarged diameter portion. apparatus. It said movable member is a single crystal growth apparatus according to claim 3, wherein a pivotable vertical plane with respect to the pulling direction of the single crystal.   The single crystal growth apparatus according to claim 1, wherein the single crystal gripping member has a plurality of the movable members arranged so as to surround the enlarged diameter portion. The single crystal growth apparatus according to claim 3 , wherein the movable member is a dish-shaped member having a slit.   The single crystal growth apparatus according to claim 1, wherein the contact member has a curved recess for stably holding the enlarged diameter portion.

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