Single crystal manufacturing equipment

Abstract

The present invention is a single crystal manufacturing device, which is based on the Czochralski method and comprises: a main chamber (2) which accommodates a crucible (6) and (7) for storing a raw material melt (5) and a heater (8) for heating the raw material melt (5); a pulling chamber (3) which is connected to the upper part of the main chamber (2) and stores a single crystal (4) pulled from the raw material melt (5); a cooling cylinder (12) which extends from the top of the main chamber (2) toward the surface of the raw material melt (5) in a manner of surrounding the single crystal (4); and a cooling auxiliary cylinder (19) which is embedded in the inner side of the cooling cylinder (12) and further comprises a diameter expansion component (20) embedded in the cooling auxiliary cylinder (19), wherein the cooling auxiliary cylinder (19) has a crack extending through the axial direction and is pressed into the diameter expansion component (20) so as to expand the diameter and fit closely with the cooling cylinder (12). Thus, the growing single crystal can be efficiently cooled and the growth rate of the single crystal can be increased.

Description

Technical Field

[0001] The present invention relates to a single crystal manufacturing device using the Czochralski Method (hereinafter referred to as CZ method). Background Art

[0002] The following describes a conventional single crystal manufacturing apparatus using the Czochralski method, taking the growth of single crystal silicon as an example.

[0003] Figure 8 An example of a conventional single crystal production apparatus is shown.

[0004] The single crystal manufacturing apparatus 101 used when manufacturing single crystal silicon by the CZ method generally comprises a crucible 106, 107 and a pulling chamber 103 connected and provided with a raw material melt 105 and movable in a vertical direction, wherein a heater 108 arranged so as to surround the crucible 106, 107 is arranged in a main chamber 102 for growing a single crystal 104, and the pulling chamber 103 is used to receive and take out the single crystal 104 grown on the upper part of the main chamber 102. When manufacturing the single crystal 104 using such a single crystal manufacturing apparatus 101, a seed crystal 116 is immersed in the raw material melt 105, and is gently pulled upward while rotating to grow the rod-shaped single crystal 104, and on the other hand, in order to obtain a desired diameter and crystal quality, the crucible 106, 107 is raised in accordance with the growth of the crystal so that the height of the melt surface is always kept constant.

[0005] Moreover, when growing a single crystal 104, after the seed crystal 116 mounted on the seed holder 117 is immersed in the raw material melt 105, the seed crystal 116 is rotated in the desired direction by a pulling mechanism (not shown), and the wire 115 is gently wound to allow the single crystal 104 to grow at the front end of the seed crystal 116. However, in order to eliminate the dislocations generated when the seed crystal 116 is immersed in the melt, the crystals in the early stage of growth are temporarily thinned to about 3 to 5 mm, and the diameter is expanded to the desired diameter at the point where the dislocations disappear, thereby growing a single crystal 104 of the target quality. Alternatively, the following method is proposed: when growing a large diameter crystal, for example, a seed crystal 116 is used, the front end of which contacts the silicon melt and is sharp or has a sharp front end cut off, the front end of the seed crystal 116 is first gently contacted with the silicon melt, and then the seed crystal 116 is lowered at a low speed so that the front end of the seed crystal 116 melts to a desired thickness, and then the seed crystal 116 is slowly raised to grow a single crystal silicon rod of a desired diameter without necking (see patent document 1).

[0006] At this time, the pulling speed of the sizing portion of the single crystal 104 having a constant diameter depends on the diameter of the pulled single crystal 104, and is a very slow speed of about 0.4 to 2.0 mm / min. If it is forced to be pulled quickly, the growing single crystal 104 will be deformed and a cylindrical product with a constant diameter cannot be obtained. Alternatively, slip dislocations will occur in the single crystal 104, or the single crystal 104 will separate from the melt and cannot become a product. There is a limit to achieving a high-speed crystal growth rate.

[0007] However, in the process of manufacturing single crystal 104 using the CZ method, in order to improve productivity and reduce costs, increasing the growth rate of single crystal 104 is an important means, and many improvements have been made to achieve the high growth rate of single crystal 104.

[0008] The growth rate of the single crystal 104 is determined by the heat balance of the growing single crystal 104. To increase the growth rate, it is known that the heat discharged from the surface of the single crystal 104 can be effectively removed. At this time, if the cooling effect of the single crystal 104 can be improved, the single crystal 104 can be manufactured more efficiently. Moreover, it is known that the quality of the crystal varies according to the cooling rate of the single crystal 104. For example, the intrinsic (Grown-in) defects formed in the growth of the single crystal in single crystal silicon can be controlled by the ratio of the temperature gradient in the crystal to the pulling speed (growth rate) of the single crystal. By controlling this, a defect-free single crystal 104 can also be grown (see patent document 2). Therefore, whether it is to manufacture defect-free crystals or to increase the growth rate of the single crystal 104 to improve productivity, it is important to improve the cooling effect of the growing single crystal 104.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Publication No. 10-203898

[0012] Patent Document 2: Japanese Patent Publication No. 11-157996

[0013] Patent Document 3: Japanese Patent Publication No. Sho 57-40119

[0014] Patent Document 4: Japanese Patent Publication No. 64-65086

[0015] Patent Document 5: International Publication No. WO01 / 57293 Pamphlet

[0016] Patent Document 6: Japanese Patent Publication No. 6-199590

[0017] Patent Document 7: Japanese Patent Publication No. 2009-161416 Summary of the invention

[0018] 1. Technical issues to be resolved

[0019] In order to efficiently cool the single crystal 104 in the CZ method, the following method is effective, that is, the radiation from the heater 108 is not directly irradiated to the crystal and the object such as the chamber that is forced to cool absorbs the radiant heat from the single crystal 104. A filter structure is cited as a structure of an apparatus that can implement this method (see patent document 3). However, in this structure, if the filter shape is set to avoid contact with the upper end of the crucible 106, 107 due to the rise of the crucible 106, 107, it is necessary to reduce the inner diameter of the upper part of the filter, and as a result, there is a disadvantage of being difficult to cool the crystal. In addition, in order to prevent contamination caused by oxidizing gas during crystal pulling, an inert gas is made to flow, but such a filter shape also has the problem that the cooling effect of the single crystal 104 cannot be expected.

[0020] Therefore, a structure has been proposed that includes a rectifying cylinder 114 for rectifying the inert gas and a heat insulating ring for shielding the rectifying cylinder 114 from direct radiation from the heater 108 and the raw material melt 105 (see Patent Document 4). In this method, the cooling effect of the single crystal 104 by the inert gas can be expected, but the cooling capacity is not high in terms of making the cooling chamber absorb the radiation heat from the single crystal 104.

[0021] Therefore, as a method for solving the above-mentioned problems of the filter screen and the rectifying cylinder 114 and efficiently cooling, a method of arranging a cooling cylinder 112 for cooling with water around the crystal has been proposed (see Patent Document 5). In this method, the outside of the cooling cylinder 112 is protected by a cooling cylinder protection material such as a protective cover made of a graphite material, and the heat of the single crystal 104 can be efficiently removed from the inside of the cooling cylinder 112. However, for safety reasons, the cooling cylinder 112 is not extended to the vicinity of the melt surface, and the cooling effect of the single crystal 104 to the cooling cylinder 112 is slightly weak.

[0022] In addition, Patent Document 6 discloses a method of extending a graphite material or the like by inserting it into a cooling tube 112. However, in this method, the cooling tube 112 and the extended graphite receive heat from the outside and cannot produce a sufficient cooling effect, and the cooling tube 112 and the graphite material are difficult to contact, so that heat cannot be efficiently transferred from the graphite material to the cooling tube 112.

[0023] Fig. 9 Another example of a conventional single crystal manufacturing apparatus is shown.

[0024] This example and Figure 8Compared with the example, the invention also has the feature of the cooling auxiliary cylinder 119. For example, in Patent Document 7, the following method is cited: the cooling auxiliary cylinder 119 is fitted into the cooling cylinder 112, and the cooling auxiliary cylinder 119 has a crack that penetrates in the axial direction and extends toward the surface of the raw material melt 105. In this method, the heat generated from the single crystal 104 is transferred to the cooling cylinder 112 via the cooling auxiliary cylinder 119, so that the pulling speed of the single crystal 104 can be increased. In addition, by making the outer diameter of the cooling auxiliary cylinder 119 the same as the inner diameter of the cooling cylinder 112, the two can be closely fitted.

[0025] However, with the recent increase in the size of single crystal manufacturing equipment, in order to smoothly fit the cooling auxiliary cylinder 119 into the cooling cylinder 112, a predetermined gap needs to be provided between the two during installation, that is, the outer diameter of the cooling auxiliary cylinder 119 needs to be smaller than the inner diameter of the cooling cylinder 112. Due to the dimensional tolerance at this time, the cooling cylinder 112 and the cooling auxiliary cylinder 119 cannot fit completely and tightly, and there is a problem of reduced efficiency of heat transfer from the cooling auxiliary cylinder 119 to the cooling cylinder 112.

[0026] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a single crystal manufacturing apparatus capable of increasing the growth rate of a single crystal by efficiently cooling the growing single crystal.

[0027] (II) Technical solution

[0028] In order to achieve the above-mentioned purpose, the present invention provides a single crystal manufacturing device, which is based on the Czochralski method and comprises: a main chamber, which accommodates a crucible for storing a raw material melt and a heater for heating the raw material melt; a pulling chamber, which is connected to the upper part of the main chamber and accommodates a single crystal pulled from the raw material melt; a cooling cylinder, which extends from the top of the main chamber toward the surface of the raw material melt in a manner of surrounding the single crystal; and a cooling auxiliary cylinder, which is embedded in the inner side of the cooling cylinder, and is characterized in that it also has a diameter expansion part embedded in the cooling auxiliary cylinder, the cooling auxiliary cylinder has a crack penetrating along the axial direction, and the diameter is expanded by pressing the diameter expansion part so as to fit tightly with the cooling cylinder.

[0029] According to such a single crystal manufacturing device, since the cooling auxiliary cylinder has a crack that runs through the axial direction, when the diameter expansion part is pressed into the cooling auxiliary cylinder, the diameter of the cooling auxiliary cylinder is expanded. In addition, by expanding the diameter of the cooling auxiliary cylinder, the cooling auxiliary cylinder and the cooling cylinder surrounding its outer circumference are closely fitted. Therefore, the heat of the pulled single crystal is efficiently transferred from the cooling auxiliary cylinder to the cooling cylinder. That is, by efficiently cooling the growing single crystal, the growth rate (crystallization pulling rate) of the single crystal is accelerated, and the productivity can be improved.

[0030] Preferably, the diameter-enlarging member has a wedge shape, and is fitted into a part or the whole of the slit of the auxiliary cooling tube and pressed in, thereby being able to enlarge the diameter of the auxiliary cooling tube.

[0031] In this way, the diameter of the auxiliary cooling cylinder can be enlarged by the diameter enlarging member having a wedge effect. Here, if the vector of the force acting in the direction of enlarging the diameter of the auxiliary cooling cylinder and the force (pressing back force) of shrinking the diameter of the auxiliary cooling cylinder by the reaction are considered, the wedge angle of the diameter enlarging member is preferably 45° or less. In addition, in order to reduce the pressing force of the diameter enlarging member toward the auxiliary cooling cylinder and facilitate the pressing of the diameter enlarging member into the auxiliary cooling cylinder, the wedge angle is more preferably 5° or more and 20° or less.

[0032] In order to function as a wedge, the interval of the slits penetrating the auxiliary cooling tube in the axial direction is preferably 1% or more and 70% or less relative to the diameter of the auxiliary cooling tube. If the pressing force of the wedge and the effect of expanding the diameter of the auxiliary cooling tube are taken into consideration, the interval is more preferably 5% or more and 20% or less relative to the diameter.

[0033] As a method of pressing the diameter-enlarging member into the auxiliary cooling tube, a method of manually pressing the diameter-enlarging member can be adopted because the auxiliary cooling tube can be easily deformed by forming a crack (slit) in the auxiliary cooling tube. However, in the case where a hard-to-deform material is used for the auxiliary cooling tube, in order to enlarge the diameter of the auxiliary cooling tube and ensure that it is closely attached to the cooling tube, a method of driving the diameter-enlarging member into the auxiliary cooling tube using a hammer or other tool can be adopted.

[0034] In addition, although the longer and thicker the cooling auxiliary tube is, the greater the heat capacity is, if the inner surface of the cooling auxiliary tube that absorbs the heat from the pulled single crystal is away from the cooling tube, the cooling effect of the single crystal is reduced. Therefore, the length of the cooling auxiliary tube protruding from the cooling tube to the bottom is preferably less than 250 mm, and the wall thickness of the cooling auxiliary tube is preferably less than 60 mm.

[0035] In addition, the longer the length (axial length) of the diameter expansion part is, the greater the diameter expansion effect of the cooling auxiliary tube is. However, if the strength of the diameter expansion part when pressed is considered, the preferred length is 10% or more and 60% or less of the length of the cooling auxiliary tube. The wall thickness of the diameter expansion part is preferably 60 mm or less, similar to the cooling auxiliary tube. At this time, in the case where the interval of the slits penetrating the cooling auxiliary tube in the axial direction is large, for example, a rectangular parallelepiped with the same interval as the slits of the cooling auxiliary tube can be connected to the front end of the wedge of the diameter expansion part.

[0036] Preferably, the auxiliary cooling tube has a tapered shape with an inner diameter decreasing downward, and the diameter-enlarging member has a tapered shape with an outer diameter decreasing downward, and is fitted into the inner side of the auxiliary cooling tube and pressed in, thereby being able to enlarge the diameter of the auxiliary cooling tube.

[0037] In this way, the cooling auxiliary cylinder and the diameter expansion component are both tapered, and the diameter expansion component is pressed into the inner side of the cooling auxiliary cylinder, so that the cooling auxiliary cylinder is opened from the inner side by the diameter expansion component, and the diameter of the cooling auxiliary cylinder can be expanded. Here, if the vector of the force acting in the direction of expanding the diameter of the cooling auxiliary cylinder and the force (pressing back force) that shrinks the diameter of the cooling auxiliary cylinder by the reaction are considered, the tapered angle of the diameter expansion component is preferably less than 45°. In addition, in order to ease the pressing force of the diameter expansion component toward the cooling auxiliary cylinder and facilitate pressing the diameter expansion component into the cooling auxiliary cylinder, the tapered angle is more preferably greater than 5° and less than 20°.

[0038] As a method of pressing the diameter-enlarging member into the cooling auxiliary cylinder, since the cooling auxiliary cylinder can be easily deformed by forming a crack penetrating in the axial direction, the diameter can be easily enlarged by splitting the cooling auxiliary cylinder, so a method of manually pressing the diameter-enlarging member can be adopted. However, in order to enlarge the diameter of the cooling auxiliary cylinder and ensure that it is closely attached to the cooling cylinder, a method of driving the diameter-enlarging member into the cooling auxiliary cylinder using a hammer or other tool can be adopted.

[0039] In addition, the amount of the diameter expansion member to be pressed in depends on the interval (difference) between the inner diameter of the cooling cylinder and the outer diameter of the cooling auxiliary cylinder. For example, if the mechanical strength of the graphite material is taken into consideration, the amount of pressing in is preferably 20 mm or less in a cooling cylinder with an inner diameter of 430 mm. In addition, in order for the diameter expansion member to contact the cooling auxiliary cylinder on the inner side of the cooling auxiliary cylinder and to improve the diameter expansion effect, the difference between the inner diameter of the upper conical portion of the cooling auxiliary cylinder and the outer diameter of the lower conical portion of the diameter expansion member is preferably 20 mm or more and 70 mm or less.

[0040] Preferably, the auxiliary cooling cylinder is made of any one of graphite material, carbon composite material, stainless steel, molybdenum, and tungsten.

[0041] This improves the heat transfer rate from the auxiliary cooling cylinder to the cooling cylinder, and thus it is possible to increase the cooling rate of the crystal.

[0042] Preferably, the diameter-enlarging member is made of any one of graphite material, carbon composite material, stainless steel, molybdenum, and tungsten.

[0043] This improves the heat transfer rate from the diameter-enlarged member to the auxiliary cooling cylinder, and thus it is possible to increase the cooling rate of the crystal.

[0044] (III) Beneficial effects

[0045] As described above, according to the present invention, it is possible to provide a single crystal production apparatus capable of increasing the growth rate of a single crystal by efficiently cooling the growing single crystal. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a cross-sectional view showing an example of a single crystal production apparatus according to the present invention.

[0047] Figure 2 It is a perspective view showing an example of an auxiliary cooling cylinder and a diameter-enlarged member.

[0048] Figure 3 It is a perspective view showing a state where the diameter-enlarged member is fitted into the auxiliary cooling cylinder.

[0049] Figure 4 It is a cross-sectional view showing another example of the single crystal production apparatus of the present invention.

[0050] Figure 5 It is a perspective view showing a part of the auxiliary cooling cylinder and an example of the diameter-enlarged member.

[0051] Figure 6 It is a perspective view showing a state where the diameter-enlarged member is fitted into the auxiliary cooling cylinder.

[0052] Figure 7 It is a cross-sectional view showing a state where the diameter-enlarged member is fitted into the auxiliary cooling cylinder.

[0053] Figure 8 It is a cross-sectional view showing an example of a conventional single crystal production apparatus.

[0054] Fig. 9 It is a cross-sectional view showing another example of a conventional single crystal production apparatus. DETAILED DESCRIPTION

[0055] As described above, in order to improve productivity and reduce costs in the production of single crystals using the CZ method, it is effective to efficiently cool the growing single crystal and increase the growth rate of the single crystal. Therefore, a structure in which a cooling cylinder surrounding the single crystal is provided in the main chamber is proposed.

[0056] In a structure that uses such a cooling cylinder to cool a growing single crystal, in order to prevent the cooling cylinder from contacting the raw material melt, the cooling cylinder is not extended to the vicinity of the liquid surface of the raw material melt. Instead, a cooling auxiliary cylinder is embedded inside the cooling cylinder and the cooling auxiliary cylinder is extended toward the liquid surface of the raw material melt. In this case, the heat generated by the growing single crystal is transferred to the cooling cylinder via the cooling auxiliary cylinder. However, in recent years, with the increase in the size of single crystal manufacturing equipment, in order to make the cooling auxiliary cylinder smoothly embedded in the cooling cylinder, the outer diameter of the cooling auxiliary cylinder is set to be smaller than the inner diameter of the cooling cylinder. As a result, it is difficult to make the two fit tightly, which causes a problem of reduced efficiency in transferring heat from the cooling auxiliary cylinder to the cooling cylinder.

[0057] The inventors of the present invention have conducted a careful study on the above-mentioned problem, and have focused on a crack (slit) provided in the axial direction on the cooling auxiliary cylinder. That is, by providing the crack on the cooling auxiliary cylinder, the diameter of the cooling auxiliary cylinder can be enlarged. For example, in order to facilitate the installation of the cooling auxiliary cylinder, even if a predetermined gap is provided between the cooling cylinder and the cooling auxiliary cylinder, the diameter of the cooling auxiliary cylinder can be enlarged after the installation so that the cooling auxiliary cylinder and the cooling cylinder are closely fitted, and the efficiency of heat transfer from the cooling auxiliary cylinder to the cooling cylinder can be improved.

[0058] Furthermore, the inventors of the present invention have carefully studied a method for increasing the diameter of the auxiliary cooling tube. That is, in a method of increasing the diameter of the auxiliary cooling tube by using the thermal expansion of the auxiliary cooling tube, a crack is provided in the auxiliary cooling tube so as to extend the diameter of the auxiliary cooling tube. Since there is a dimensional tolerance between the inner diameter of the auxiliary cooling tube and the outer diameter of the auxiliary cooling tube, and there is a deviation in the gap between the two, there is a case where the diameter of the auxiliary cooling tube cannot be increased sufficiently to ensure that the auxiliary cooling tube is closely attached to the cooling tube.

[0059] Therefore, the inventors of the present invention have repeatedly and carefully studied the method of expanding the diameter of the cooling auxiliary cylinder, and found that by re-setting the diameter expansion component embedded in the cooling auxiliary cylinder and pressing the diameter expansion component to expand the diameter of the cooling auxiliary cylinder, the cooling auxiliary cylinder can be made to fit tightly with the cooling cylinder, thereby completing the present invention.

[0060] That is, the present invention is a single crystal manufacturing device, which is based on the Czochralski method and comprises: a main chamber, which accommodates a crucible for storing a raw material melt and a heater for heating the raw material melt; a pulling chamber, which is connected to the upper part of the main chamber and accommodates a single crystal pulled from the raw material melt; a cooling cylinder, which extends from the top of the main chamber toward the surface of the raw material melt in a manner of surrounding the single crystal; and a cooling auxiliary cylinder, which is embedded in the inner side of the cooling cylinder, and is characterized in that it also has a diameter expansion part embedded in the cooling auxiliary cylinder, the cooling auxiliary cylinder has a crack penetrating along the axial direction, and the diameter is expanded by pressing the diameter expansion part so as to fit tightly with the cooling cylinder.

[0061] Hereinafter, embodiments of the present invention will be described in detail based on the drawings, but the present invention is not limited thereto.

[0062] Figure 1 An example of the single crystal production apparatus of the present invention is shown.

[0063] In the single crystal manufacturing apparatus 1, a quartz crucible 6 contains a raw material melt (e.g., silicon melt) 5, a heater 8 heats and melts the raw material crystal (e.g., polycrystalline silicon) to generate the raw material melt 5, and the raw material melt 5 is maintained at an appropriate temperature. A seed holder 17 for mounting a seed crystal 16 is connected to the front end of the pulling wire 15.

[0064] The quartz crucible 6 is provided in a state of being held by the graphite crucible 7, and the graphite crucible 7 is supported by a crucible rotating shaft (support shaft) 18 that rotates at the center of the bottom and moves up and down. A pulling chamber 3 is provided above the main chamber 2, and the pulling chamber 3 is provided with an opening door for taking out a single crystal (for example, single crystal silicon) 4 pulled from the raw material melt 5.

[0065] A gas inlet 11 for introducing an atmospheric gas (e.g., Ar gas) is provided in the pulling chamber 3, and a gas outlet 10 for discharging the introduced atmospheric gas is provided at the bottom of the main chamber 2. Then, while introducing the atmospheric gas from the gas inlet 11, the seed crystal 16 is immersed in the raw material melt 5, and while the pulling wire 15 is rotated and wound, the single crystal 4 is pulled.

[0066] The quartz crucible 6 and the graphite crucible 7 can be raised / lowered along the crystal growth axis via the crucible rotation axis 18, and can be raised in a manner to supplement the lowered portion of the liquid level of the raw material melt 5 that is lowered by crystallization during crystal growth. In addition, the heat insulating member 9 surrounds the outer side of the heater 8 (the opposite side of the crucible 6, 7 side) to prevent the heat from the heater 8 from being directly radiated to the main chamber 2, and to prevent the heat loss of the molten raw material melt 5.

[0067] In addition, in order to increase the growth rate of the single crystal 4, it is necessary to rapidly cool the single crystal 4, so a cooling cylinder 12 is provided. The cooling cylinder 12 is made of metal, for example, and coaxially surrounds the pulled single crystal 4. In addition, the interior of the cooling cylinder 12 is hollow, and the cooling medium (such as water, etc.) introduced from the cooling medium inlet 13 circulates in the hollow of the cooling cylinder 12 to cool the cooling cylinder 12 and is then discharged to the outside.

[0068] The rectifying cylinder 14 coaxially surrounds the pulled single crystal 4 and extends from the lower end of the cooling cylinder 12 toward the lower side of the cooling cylinder 12. The rectifying cylinder 14 has a rectifying effect on the inert gas introduced from the gas inlet 11 and shields the radiation heat from the heater 8 and the raw material melt 5, thereby improving the cooling effect of the single crystal 4. In addition, the rectifying cylinder 14 is located below the lower end of the cooling cylinder 12, thereby preventing the cooling cylinder 12 from contacting the raw material melt 5 and causing a water vapor explosion.

[0069] The auxiliary cooling cylinder 19 is fitted inside the cooling cylinder 12. One of the functions of the auxiliary cooling cylinder 19 is to absorb radiation from the pulled single crystal 4 and transfer it to the cooling cylinder 12. Therefore, the auxiliary cooling cylinder 19 coaxially surrounds the pulled single crystal 4 and extends downward further than the lower end of the cooling cylinder 12. In this case, the auxiliary cooling cylinder 19 can surround the single crystal 4 to the bottom, and can effectively transfer the heat from the single crystal 4 to the cooling cylinder 12 via the auxiliary cooling cylinder 19.

[0070] At this time, in order to maximize the cooling effect of the single crystal 4, it is important to make the cooling auxiliary cylinder 19 fit closely with the cooling cylinder 12 and effectively transfer the heat from the cooling auxiliary cylinder 19 to the cooling cylinder 12. Therefore, in the present invention, a diameter expansion member 20 is used to be fitted in the cooling auxiliary cylinder 19, and the diameter of the cooling auxiliary cylinder 19 is expanded by pressing the diameter expansion member 20 so that it fits closely with the cooling cylinder 12. A specific example of expanding the diameter of the cooling auxiliary cylinder 19 is described below.

[0071] Figure 2 This shows an example of a cooling auxiliary cylinder and a diameter-enlarged part.

[0072] The auxiliary cooling cylinder 19 has a cylindrical shape with the axis AX as the center. The axis AX substantially coincides with the crystal growth axis during single crystal growth.

[0073] The cooling auxiliary cylinder 19 has a slit SL extending in the axial direction. The upper portion of the slit SL is a fitting portion F cut in a V shape. The slit SL has the effect of facilitating the installation of the cooling auxiliary cylinder 19. In addition, the fitting portion F has the effect of expanding the diameter of the cooling auxiliary cylinder 19 by fitting the diameter expansion component 20. In this example, the fitting portion F is in the shape of an inverted triangle, and the angle θ1' at the lowermost end (the vertex of the inverted triangle) is set to, for example, 5° or more and 20° or less.

[0074] The diameter-enlarged member 20 has a wedge shape and is fitted in part or all of the fitting portion F. Specifically, the diameter-enlarged member 20 has an inverted triangle shape whose width decreases toward the lower end, and the taper angle (wedge angle) θ1 at the lowermost end (vertex of the inverted triangle) is preferably the same as the angle θ1' at the fitting portion F, for example, set to be greater than 5° and less than 20°.

[0075] When the auxiliary cooling cylinder 19 and the enlarged diameter member 20 are used, when the enlarged diameter member 20 is fitted into the auxiliary cooling cylinder 19 and pressed in, as shown in FIG. Figure 3 As shown, the pressing pressure of the diameter expansion member 20 is converted into a force for expanding the diameter of the cooling auxiliary cylinder 19, and the diameter of the cooling auxiliary cylinder 19 is expanded. As a result, the cooling auxiliary cylinder 19 is firmly and tightly fitted to the cooling cylinder 12 (see Figure 1 ). In addition, the material of the cooling auxiliary cylinder 19 and the diameter expansion member 20 is preferably a material with excellent heat resistance, high thermal conductivity and high emissivity, such as any one of graphite material, carbon composite material (CC material), stainless steel, molybdenum, and tungsten.

[0076] Figure 4 Another example of the single crystal production apparatus of the present invention is shown.

[0077] The single crystal manufacturing apparatus 1 ′ shown in the figure is Figure 1 Compared with the single crystal manufacturing device 1 of FIG. 1 , except for the difference between the cooling auxiliary cylinder 19 and the diameter expansion member 20, Figure 1 Therefore, the cooling auxiliary cylinder 19 and the diameter expansion member 20 are described below, and the other components are marked with Figure 1 The same reference numerals are used and detailed description thereof is omitted.

[0078] Figure 5 An example of a part of the auxiliary cooling cylinder and the diameter-enlarged member is shown. Figure 6 and Figure 7 This shows the state where the diameter-enlarged member is fitted into the auxiliary cooling cylinder.

[0079] The auxiliary cooling tube 19 has four slits SL extending in the axial direction, and the auxiliary cooling tube 19 is divided into four parts A, B, C, and D by the four slits SL. That is, if the four parts A, B, C, and D are combined, the auxiliary cooling tube 19 becomes a cylindrical shape centered on the axis AX. In addition, Figure 5 The cooling auxiliary cylinder 19 shown is Figure 6 Corresponding to one of the four parts A, B, C, D.

[0080] like Figure 7 As shown, the cooling auxiliary cylinder 19 has a conical shape, and its upper inner surface is inclined and its inner diameter decreases downward, that is, the cross-sectional width narrows toward the upper end. On the other hand, the diameter-enlarging component 20 has a ring shape that is fitted inside the cooling auxiliary cylinder 19. In addition, the diameter-enlarging component 20 has a conical shape, and its lower outer surface is inclined and its outer diameter decreases downward, that is, the cross-sectional width narrows toward the lower end.

[0081] In addition, when the angle formed by the inner surface and the outer surface of the cooling auxiliary cylinder 19 is set to the tapered angle θ2, the tapered angle θ2 is set to, for example, 5° or more and 20° or less. Similarly, when the angle formed by the inner surface and the outer surface of the diameter-enlarged component 20 is set to the tapered angle θ2', the tapered angle θ2' is preferably the same as the tapered angle θ2 of the cooling auxiliary cylinder 19, and is set to, for example, 5° or more and 20° or less.

[0082] When the auxiliary cooling cylinder 19 and the enlarged diameter member 20 are used, when the enlarged diameter member 20 is fitted into the auxiliary cooling cylinder 19 and pressed in, Figure 6 and Figure 7 As shown, the pressing pressure of the diameter expansion member 20 is converted into a force for expanding the diameter of the cooling auxiliary cylinder 19, and the diameter of the cooling auxiliary cylinder 19 is expanded. As a result, the cooling auxiliary cylinder 19 is firmly and tightly fitted to the cooling cylinder 12 (see Figure 4 ). In addition, the material of the cooling auxiliary cylinder 19 and the diameter expansion member 20 is preferably a material with excellent heat resistance, high thermal conductivity and high emissivity, such as any one of graphite material, carbon composite material (CC material), stainless steel, molybdenum, and tungsten.

[0083] As described above, according to the single crystal manufacturing device of the present invention, since the cooling auxiliary cylinder 19 has the slit SL penetrating in the axial direction, when the diameter expansion part 20 is pressed into the cooling auxiliary cylinder 19, the diameter of the cooling auxiliary cylinder 19 is expanded. In addition, by expanding the diameter of the cooling auxiliary cylinder 19, the cooling auxiliary cylinder 19 is closely fitted with the cooling cylinder 12 surrounding its outer circumference. Therefore, the heat of the pulled single crystal 4 is efficiently transferred from the cooling auxiliary cylinder 19 to the cooling cylinder 12. That is, by efficiently cooling the growing single crystal 4, the growth rate (crystallization pulling rate) of the single crystal 4 is increased, and the productivity can be improved.

[0084] Example

[0085] The present invention will be described in detail below with reference to the following examples, but the present invention is not limited thereto.

[0086] (Example 1)

[0087] In Example 1, the following conditions were used to set Figure 1 The single crystal production apparatus 1 was used to grow a single crystal 4, and the crystal pulling speed at which the single crystal 4 of the desired quality could be obtained was verified.

[0088] The grown single crystal 4 is single crystal silicon, and a silicon crystal with a diameter of 12 inches (300 mm) is produced by applying a magnetic field Czochralski method (MCZ method). The diameter of the quartz crucible 6 is 32 inches (800 mm). The design value of the inner diameter of the cooling cylinder 12 is 430 mm, the design value of the outer diameter of the cooling auxiliary cylinder 19 is 429.5 mm, and its length is 350 mm. The components used have tolerances of ±0.4 mm and ±0.1 mm for the inner diameter of the cooling cylinder 12 and the outer diameter of the cooling auxiliary cylinder 19, respectively.

[0089] like Figure 2 As shown, a component having a slit SL penetrating in the axial direction and a fitting portion F cut in a V-shape at the upper part of the slit SL is used as the cooling auxiliary cylinder 19. In addition, a component having a wedge shape that fits into a part or all of the fitting portion F is used as the diameter expansion component 20. Specifically, the diameter expansion component 20 is in the shape of an inverted triangle whose width decreases toward the lower end, and the taper angle θ1 at the lowest end is set to 10°. The fitting portion F of the cooling auxiliary cylinder 19 is also in the shape of an inverted triangle, and the angle θ1' at the lowest end is set to 10°.

[0090] In such a single crystal manufacturing device 1, the interval (difference) between the inner diameter of the cooling cylinder 12 and the outer diameter of the cooling auxiliary cylinder 19 immediately after the cooling auxiliary cylinder 19 is set is 0.8 mm, and the cooling auxiliary cylinder 19 is expanded to a desired diameter by fitting the diameter expansion member 20 into the cooling auxiliary cylinder 19 and pressing the diameter expansion member 20, so that the interval between the inner diameter of the cooling cylinder 12 and the outer diameter of the cooling auxiliary cylinder 19 becomes 0 mm. That is, the cooling auxiliary cylinder 19 can be completely and tightly fitted to the cooling cylinder 12. In addition, as the material of the cooling auxiliary cylinder 19 and the diameter expansion member 20, a graphite material having a thermal conductivity comparable to that of metal and a higher emissivity than that of metal is used.

[0091] In addition, the single crystal 4 was grown in a state where the cooling cylinder 12 and the cooling auxiliary cylinder 19 were closely attached to each other by the diameter expansion member 20, and the growth rate at which all the crystals were defect-free was obtained. As for the growth rate for obtaining defect-free crystals, the margin is very narrow, so by cutting out a sample from the pulled single crystal 4 and confirming whether it is a defect-free crystal, it is easy to determine the appropriate growth rate for obtaining a single crystal 4 that is defect-free. In Example 1, based on the sample, it was confirmed by selective etching whether it was a defect-free crystal, and the growth rate at which all the crystals were defect-free was obtained.

[0092] (Comparative Example 1)

[0093] In Comparative Example 1, Figure 8 The growth rate of the single crystal 104 which is entirely defect-free crystal was obtained by using the single crystal production apparatus 101 of Comparative Example 1. That is, in Comparative Example 1, the growth rate in the case of using the single crystal production apparatus 101 without the auxiliary cooling cylinder was evaluated.

[0094] In addition, in Comparative Example 1, in addition to using Figure 8 Except for the single crystal manufacturing apparatus, single crystal 104 was manufactured under the same conditions as in Example 1 and the same evaluation as in Example 1 was performed.

[0095] In addition, Figure 8 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, and 118 correspond to Figure 1 The main chamber 2, the pulling chamber 3, the single crystal 4, the raw material melt 5, the quartz crucible 6, the graphite crucible 7, the heater 8, the insulation component 9, the gas outflow port 10, the gas inlet port 11, the cooling tube 12, the cooling medium inlet port 13, the rectifying tube 14, the pulling wire 15, the seed crystal 16, the seed holder 17, and the crucible rotating shaft 18.

[0096] (Comparative Example 2)

[0097] In Comparative Example 2, using Fig. 9 The growth rate of the single crystal 104 which is entirely defect-free crystal was obtained by using the single crystal production apparatus 101 of Comparative Example 2. That is, the growth rate when the single crystal production apparatus 101 having the auxiliary cooling cylinder but not the diameter-enlarging member was used was evaluated.

[0098] In addition, in Comparative Example 2, in addition to using Fig. 9 Except for the single crystal manufacturing apparatus, single crystal 104 was manufactured under the same conditions as in Example 1 and the same evaluation as in Example 1 was performed.

[0099] In addition, Fig. 9In Figure 8 The same reference numerals are used to mark the same components. Fig. 9 In, 119 corresponds to Figure 1 A cooling auxiliary cylinder 19 in the.

[0100] Table 1 shows the crystal pulling speed (growth speed) at which all the pulled single crystals are defect-free crystals for Example 1, Comparative Example 1, and Comparative Example 2.

[0101] [Table 1]

[0102] Comparison of the crystallization pulling speeds of Example 1, Comparative Example 1 and Comparative Example 2

[0103] structure Crystallization pulling speed No cooling auxiliary cylinder (Comparative Example 1) 1.000 Only cooling auxiliary cylinder (Comparative Example 2) 1.058 Cooling auxiliary cylinder + diameter expansion component (Example 1) 1.105

[0104] As is clear from Table 1, in Example 1, the growth rate was increased by about 10.5% compared to Comparative Example 1 which did not use the auxiliary cooling cylinder. In addition, in Example 1, the growth rate was increased by about 4.4% compared to Comparative Example 2 which used the auxiliary cooling cylinder but did not use the diameter expansion member.

[0105] (Example 2)

[0106] In Example 2, the following conditions are used to set Figure 4 The single crystal production apparatus 1 ′ was used to grow a single crystal 4 and the crystal pulling speed capable of obtaining a single crystal 4 of desired quality was verified.

[0107] The grown single crystal 4 is single crystal silicon, except that Figure 5 The single crystal was manufactured under the same conditions as in Example 1, and the same evaluation as in Example 1 was performed except for the cooling auxiliary cylinder 19 and the diameter-enlarged component 20 shown. That is, the design value of the inner diameter of the cooling cylinder 12 was 430 mm, the design value of the outer diameter of the cooling auxiliary cylinder 19 was 429.5 mm, and the length thereof was 350 mm. In addition, components with tolerances of ±0.4 mm and ±0.1 mm for the inner diameter of the cooling cylinder 12 and the outer diameter of the cooling auxiliary cylinder 19 were used.

[0108] like Figure 6 As shown in FIG. 1 , a cooling auxiliary tube 19 having four slits SL extending in the axial direction and divided into four parts A, B, C, and D by the four slits SL is used as the cooling auxiliary tube 19. Figure 7 As shown, the cooling auxiliary cylinder 19 is a component that has an inclined inner surface at its upper portion and a tapered cross-sectional shape that becomes narrower toward the upper end. Figure 7As shown, a ring-shaped member fitted inside the auxiliary cooling cylinder 19 is used as the diameter-enlarged member 20. The diameter-enlarged member 20 has an inclined outer surface at the lower portion and a tapered cross-sectional shape that narrows toward the lower end.

[0109] In addition, a taper angle θ2 formed between the inner surface and the outer surface of the auxiliary cooling cylinder 19 and a taper angle θ2′ formed between the inner surface and the outer surface of the enlarged diameter member 20 were each set to 10°.

[0110] In such a single crystal manufacturing device 1', the interval (difference) between the inner diameter of the cooling cylinder 12 and the outer diameter of the cooling auxiliary cylinder 19 immediately after the cooling auxiliary cylinder 19 is set is 0.8 mm, and by fitting the diameter expansion member 20 in the cooling auxiliary cylinder 19 and pressing the diameter expansion member 20, the four parts of the cooling auxiliary cylinder 19 are respectively moved in the radial direction, and the cooling auxiliary cylinder 19 is expanded to the desired diameter, so that the interval between the inner diameter of the cooling cylinder 12 and the outer diameter of the cooling auxiliary cylinder 19 becomes 0 mm. That is, the cooling auxiliary cylinder 19 can be completely and tightly fitted to the cooling cylinder 12.

[0111] Table 2 shows the crystal pulling speed (growth speed) at which all the pulled single crystals are defect-free crystals for Example 2, Comparative Example 1, and Comparative Example 2.

[0112] [Table 2]

[0113] Comparison of the crystallization pulling speeds of Example 2, Comparative Example 1 and Comparative Example 2

[0114] structure Crystallization pulling speed No cooling auxiliary cylinder (Comparative Example 1) 1.000 Only cooling auxiliary cylinder (Comparative Example 2) 1.058 Cooling auxiliary cylinder + diameter expansion component (Example 2) 1.102

[0115] As is clear from Table 2, in Example 2, the growth rate was increased by about 10.2% compared to Comparative Example 1 which did not use the auxiliary cooling cylinder. In addition, in Example 2, the growth rate was increased by about 4.1% compared to Comparative Example 2 which used the auxiliary cooling cylinder but did not use the diameter expansion member. That is, in Example 2, the growth rate was increased to the same degree as in Example 1.

[0116] The above results show that Examples 1 and 2 can achieve a higher growth rate of single crystal 4 than Comparative Examples 1 and 2. That is, it is proven that the single crystal manufacturing apparatuses 1 and 1' of the present invention can efficiently cool the growing single crystal 4 and achieve a higher growth rate of single crystal 4.

[0117] As described above, according to the present invention, the outer diameter of the cooling auxiliary cylinder 19 can be enlarged by fitting the cooling auxiliary cylinder 19 into the diameter-enlarging member 20 and pressing it in. As a result, the degree of close contact between the cooling auxiliary cylinder 19 and the cooling cylinder 12 can be improved, and the growing single crystal 4 can be efficiently cooled. That is, by efficiently cooling the growing single crystal 4, the growth rate of the single crystal 4 can be increased.

[0118] The present invention is not limited to the above-mentioned embodiments. The above-mentioned embodiments are for illustrative purposes only, and any solution having substantially the same structure and producing the same function and effect as the technical concept described in the claims of the present invention is included in the technical scope of the present invention.

Claims

1. A single crystal manufacturing device based on the Czochralski method, comprising: a main chamber that accommodates a crucible for storing a raw material melt and a heater for heating the raw material melt; a pulling chamber that is connected to the upper part of the main chamber and stores a single crystal pulled from the raw material melt; a cooling cylinder that extends from the top of the main chamber toward the surface of the raw material melt in a manner of surrounding the single crystal; and a cooling auxiliary cylinder that is embedded in the inner side of the cooling cylinder, It is characterized in that It also includes a diameter enlarged member fitted into the cooling auxiliary cylinder, The cooling auxiliary cylinder has a crack extending through the axial direction, and the diameter is expanded by pressing the diameter expansion component so as to fit closely with the cooling cylinder. The cooling auxiliary cylinder has a tapered shape with an inner diameter decreasing downward. The diameter-enlarging member has a tapered shape whose outer diameter decreases downward, and is fitted into the inner side of the auxiliary cooling tube and pressed in, thereby being able to enlarge the diameter of the auxiliary cooling tube.

2. The single crystal manufacturing device according to claim 1, characterized in that: The cooling auxiliary cylinder is made of any one of graphite material, carbon composite material, stainless steel, molybdenum, and tungsten.

3. The single crystal manufacturing device according to claim 1 or 2, characterized in that: The material of the diameter-enlarged member is any one of graphite material, carbon composite material, stainless steel, molybdenum, and tungsten.

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