JP2017154926A - Manufacturing apparatus and manufacturing method of silicon carbide single crystal ingot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing apparatus and a manufacturing method of a silicon carbide single crystal ingot capable of efficiently sublimating a silicon carbide raw material loaded in a crucible during growth of a silicon carbide single crystal and manufacturing a silicon carbide single crystal ingot having a large diameter and a long size.SOLUTION: An apparatus for manufacturing a silicon carbide single crystal by a sublimation crystallization process includes a crucible 1 having a crucible body 1a, a crucible top cover 1b, and a raw material loading part for loading a silicon carbide raw material 3 that is located at the lower part of the crucible body 1b, and a work coil 7 located outside the crucible 1 for heating the crucible body 1a by high-frequency induction heating. A heating member 7 having a non-axial-symmetric shape to a central axis of the crucible body 1a and capable of practicing the high-frequency induction heating is installed outside the raw material loading part. A manufacturing apparatus of a silicon carbide single crystal ingot 4 is equipped with a rolling mechanism for relatively rotating the heating member 7 and the crucible body 1a around the central axis of the crucible body 1a. A manufacturing method of the silicon carbide single crystal ingot 4 uses the apparatus.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a silicon carbide single crystal ingot production apparatus used for producing a silicon carbide single crystal ingot by growing a silicon carbide single crystal by a sublimation recrystallization method using a seed crystal, and a carbonization using the production apparatus. The present invention relates to a method for producing a silicon carbide single crystal ingot for producing a silicon single crystal ingot.

  A silicon carbide single crystal having high thermal conductivity and a large band gap is a useful material as a substrate for electronic materials used at high temperatures and electronic materials that require high breakdown voltage. As one method for producing such a silicon carbide single crystal, a sublimation recrystallization method (Rayleigh method) is known. This sublimation recrystallization method is a method for producing a silicon carbide single crystal by sublimating a raw material silicon carbide powder at a high temperature exceeding 2000 ° C. and recrystallizing the generated sublimation gas (raw material gas) to a low temperature part. is there. Further, in this Rayleigh method, a method of producing a silicon carbide single crystal using a seed crystal composed of a silicon carbide single crystal is called an improved Rayleigh method (Non-patent Document 1), and is a bulk silicon carbide single crystal ingot. It is used for manufacturing.

  In this improved Rayleigh method, since a seed crystal is used, the nucleation process of the crystal can be optimized, and by adjusting the atmospheric pressure by an inert gas to about 10 Pa to 15 kPa, a silicon carbide single crystal The reproducibility of the growth rate and the like can be improved. For this reason, generally, an appropriate temperature difference is provided between the raw material and the seed crystal, and a silicon carbide single crystal is grown on the seed crystal. Further, the obtained silicon carbide single crystal (silicon carbide single crystal ingot) is used after being subjected to processing such as grinding, cutting, and polishing in order to obtain a standard shape as a substrate of an electronic material.

Here, the principle of the improved Rayleigh method will be described with reference to FIG.
As the silicon carbide raw material 3 used in the sublimation recrystallization method, a silicon carbide crystal powder [usually, a silicon carbide crystal powder produced by the Acheson method is washed and pretreated is used. As the graphite crucible 1, a crucible provided with a cylindrical crucible main body 1a having an upper end opening and a crucible upper lid 1b for closing the upper end opening of the crucible main body 1a is used. The silicon carbide raw material 3 is filled in the raw material filling portion 1c below the crucible body 1a, and a seed crystal 2 made of a silicon carbide single crystal is installed on the inner surface of the crucible upper lid 1b. In the crucible 1, the silicon carbide raw material 3 is heated to 2400 ° C. or higher in an inert gas atmosphere such as argon (10 Pa to 15 kPa). During this heating, a temperature gradient is set in the crucible 1 so that the temperature of the seed crystal 2 side is slightly lower than that of the silicon carbide raw material 3 side, and the silicon sublimation gas sublimated from the silicon carbide raw material 3 is heated and sublimated. Is diffused in the direction of the seed crystal 2 due to the concentration gradient (formed by the temperature gradient), transported, recrystallized on the surface of the seed crystal 2, and crystal growth proceeds to produce a single crystal ingot 4. In addition, the code | symbol 5 is a heat insulating material in FIG.

  By the way, the diameter of the silicon carbide single crystal substrate is required to be increased in order to reduce the manufacturing cost as much as possible when used as a substrate for manufacturing an electronic device. For this reason, with respect to the ingot for manufacturing a silicon carbide single crystal substrate, it is possible to manufacture a large number of substrates from one ingot at the same time as increasing its diameter, and during cutting and grinding. In order to further increase the productivity, it is also required to lengthen the ingot obtained by crystal growth. However, in the improved Rayleigh method, since the crystal growth is performed by the method as described above, it is difficult to add the silicon carbide raw material during the crystal growth. Therefore, in order to produce a large-diameter and long-sized silicon carbide single crystal ingot, it is necessary to fill a large amount of silicon carbide raw material in the crucible raw material filling portion as compared with the case of crystal growth of a small-diameter ingot. The diameter and depth of the raw material filling portion need to be increased, but in order to effectively use the silicon carbide raw material filled in this way for crystal growth, the entire silicon carbide raw material in the raw material filling portion It is indispensable to efficiently heat and sublimate to sublimation temperature.

  And, as a method of heating the silicon carbide raw material in the crucible, generally, the graphite crucible is heated using high frequency induction heating, the silicon carbide raw material is heated through the heated crucible, and the above described crucible is put in the crucible. A temperature gradient is formed. In addition, in such high frequency induction heating, since the generation of the induced high frequency current depends on the penetration depth of the high frequency, a heat generation distribution determined by the shape of the crucible is generated, and near the inner surface of the crucible side wall. Strong heat generation occurs, and this heat is transmitted to the silicon carbide raw material in the raw material filling portion by heat conduction or radiation, thereby heating the silicon carbide raw material. Focusing on the silicon carbide raw material filled in the raw material filling portion of the crucible, when the crucible is cylindrical and the silicon carbide raw material is filled in the raw material filling portion in a cylindrical shape, Since the side surface of the silicon carbide raw material is strongly heated, the vicinity of the outer peripheral portion of the silicon carbide raw material (the outer peripheral portion of the raw material filling portion of the crucible) is more easily heated, and the central axis of the silicon carbide raw material (the center of the raw material filling portion of the crucible) There is a tendency that the heating temperature for the silicon carbide raw material is higher than that in the vicinity of the axis) and the temperature of the silicon carbide raw material decreases from the outer periphery of the silicon carbide raw material toward the central axis.

  When the raw material filling part is heated in this way, the silicon carbide raw material in the raw material filling part becomes a high temperature part in the vicinity of the outer peripheral part, and sublimation gas is generated from this high temperature part, and crystal growth occurs on the seed crystal. The silicon carbide raw material in the raw material filling portion has a low temperature portion in the vicinity of the central axis, and inevitably a temperature distribution occurs between the high temperature portion and the low temperature portion, and the raw material in the vicinity of the central axis of the raw material filling portion becomes the low temperature portion. . And in order to raise the temperature of this low temperature part to the sublimation temperature and sublimate the raw material near the central axis that becomes the low temperature part, the current value of the induced current is increased and the temperature of the side wall part of the graphite crucible is made higher. There is a need to. However, when the temperature of the side wall portion of the crucible is increased, the temperature of the entire crucible is increased, the temperature of the seed crystal and the growing single crystal is also increased, and the temperature gradient between the seed crystal and the raw material is reduced. The driving force of crystal growth based on the above becomes small, and there is a problem of crystal growth stop that stops crystal growth in the middle.

In view of this, conventionally, for example, several proposals have been made as to the method of heating the raw material filling portion as shown below.
In order to prevent lowering of the temperature of the bottom wall part of the crucible material filling part (crucible bottom wall part), by arranging a heat insulating material on the crucible bottom wall part, recrystallization in the lower part of the raw material filling part is suppressed and efficient. Discloses a method of heating a raw material (Patent Document 1). Moreover, the method of making the temperature distribution inside a raw material uniform by devising the shape of the side wall of the crucible of a raw material filling part is disclosed (patent document 2). Furthermore, as a method of directly heating such a crucible bottom wall, a method of disposing an induction heating coil under the crucible bottom wall is disclosed (Patent Document 3). Furthermore, a method of disposing a heat generating member on the crucible side wall portion and improving the temperature controllability of the raw material portion is disclosed (Patent Document 4). And the method of making the quality of the grown crystal high is disclosed by making temperature distribution of the seed crystal vicinity part into non-axisymmetric temperature distribution (patent document 5).

JP 2010-76,990 JP 2007-230,846 JP 2013-216,549 JP-A-2014-234,331 JP 2012-131,679 A

Yu. M. Tairov and V. F. Tsvetkov, Journal of Crystal Growth, 52 (1981) pp.146

  However, in the method of Patent Document 1, since the heat generating part is the side wall part of the crucible, the problem that the temperature in the vicinity of the central axis of the raw material filling part is lower than the temperature of the outer peripheral part still remains, Therefore, when the diameter of the crucible is increased, this method is difficult to adopt for the purpose of efficiently heating the raw material in the vicinity of the central axis of the raw material filling portion. Further, in the method of Patent Document 2, the heat generation distribution in the vicinity of the crystal growth portion growing on the seed crystal also changes as the heat generation distribution on the side wall of the crucible changes, and the crystal growth becomes an isotherm. Since the shape of the growth surface of the crystal that grows with the change in the heat generation distribution is also affected, both the temperature equalization of the raw material filling portion and the optimization of the temperature of the crystal growth portion are compatible. Therefore, it is very difficult to achieve both soaking and optimization.

  Further, in the method of Patent Document 3, the lower part of the crucible can be directly heated. However, since the structure of the apparatus is complicated, the side induction heating coil and the lower induction heating coil interact with each other. It is very difficult to optimize the current flowing through the induction heating coil. Furthermore, in the method of Patent Document 4, it is still necessary to transmit heat from the outer peripheral portion to the central portion, and it is difficult to efficiently heat the central portion that is far from the outer peripheral portion where the heat is generated. Furthermore, in the method of Patent Document 5, a non-axisymmetric temperature distribution can be formed inside the crucible so that a portion that is difficult to heat can be moved from the central axis. The temperature distribution of the central part of the raw material that is far from the growing crystal is not changed, the temperature of the central part of the raw material is still low, and the raw material in the central part is efficiently sublimated. It is difficult.

  The present invention efficiently sublimates the silicon carbide raw material filled in the raw material filling portion of the crucible during the growth of the silicon carbide single crystal, and the silicon carbide single crystal ingot is not particularly limited. An object of the present invention is to provide a method for producing a silicon carbide single crystal ingot suitable for efficiently producing a long silicon carbide single crystal ingot.

  The present inventors diligently studied a method for efficiently sublimating a silicon carbide raw material filled in a raw material filling portion of a graphite crucible when producing a silicon carbide single crystal ingot by high frequency induction heating. As a result, a heating member having a non-axisymmetric shape with respect to the center axis of the crucible and capable of high-frequency induction heating is disposed outside the raw material filling portion of the crucible, and the silicon carbide raw material in the raw material filling portion is non-axisymmetric. By heating, the low temperature part in the raw material filling part which has been conventionally on the central axis of the crucible body can be shifted to a position different from that on the central axis, and the heating member and the crucible are further moved to the center of the crucible. By relatively rotating the axis as a rotation axis, a non-axisymmetric temperature distribution is moved around the central axis of the crucible during crystal growth, and the raw material near the central axis in the raw material filling part is efficiently heated. As a result, it was found that temperature equalization of the raw material filling portion can be achieved.

  According to this method, the raw material that is most difficult to be heated in the vicinity of the central axis of the raw material filling portion of the crucible by the conventional axisymmetric heating can be effectively heated and sublimated. The present invention was completed by finding that even a large-diameter and long silicon carbide single crystal ingot can be produced by efficiently sublimating the silicon carbide raw material filled in the part.

That is, the gist of the present invention is as follows.
(1) It has a graphite crucible body formed in a cylindrical shape with an upper end opening and a graphite crucible upper lid that closes the upper end opening of the crucible body, and the lower part of the crucible body is filled with silicon carbide raw material A silicon carbide single crystal for producing a silicon carbide single crystal by a sublimation recrystallization method, comprising a crucible having a raw material filling portion and a work coil disposed outside the crucible and generating heat from the crucible body by high frequency induction heating In ingot production equipment,
Outside the raw material filling portion at the lower part of the crucible body, a heating member that has a non-axisymmetric shape with respect to the central axis of the crucible body and generates heat by high-frequency induction heating by the work coil is disposed. An apparatus for manufacturing a silicon carbide single crystal ingot, comprising: a rotation mechanism that relatively rotates a heat generating member and the crucible body about a central axis of the crucible body.
(2) Cylindrical heating having a non-axisymmetric shape in which the heat generating member is disposed so as to surround the outer side of the raw material filling portion at the lower part of the crucible body, and the central axis of the outer periphery is eccentric to the central axis of the inner periphery The apparatus for producing a silicon carbide single crystal ingot according to (1), wherein the apparatus is a member.
(3) The silicon carbide single crystal according to (1) or (2), wherein the heat generating member has a height of 0.6 to 1 times the height of the raw material filling portion Ingot manufacturing equipment.
(4) The silicon carbide according to any one of (1) to (3), wherein a relative rotation speed between the heat generating member and the crucible body is 2 to 60 rotations per hour. Single crystal ingot manufacturing equipment.
(5) The silicon carbide raw material filled in the raw material filling portion at the lower part of the graphite crucible body is heated and sublimated, and the generated sublimation gas is a seed crystal composed of a silicon carbide single crystal installed on the inner surface of the crucible upper lid. In the method for producing a silicon carbide single crystal ingot to be recrystallized on the surface,
A heat generating member capable of high-frequency induction heating having a non-axisymmetric shape with respect to the central axis of the crucible body is disposed outside the raw material filling portion at the lower part of the crucible body, and the heat generating member and the crucible body are connected to the crucible body. The silicon carbide is heated while causing the crucible body and the heat generating member to generate heat by high-frequency induction heating while relatively rotating about the central axis of the material, and forming a non-axisymmetric temperature distribution inside the raw material filling portion A method for producing a silicon carbide single crystal ingot, wherein the raw material is sublimated.

  According to the silicon carbide single crystal ingot manufacturing apparatus of the present invention, when the silicon carbide single crystal ingot is efficiently grown using the graphite crucible, the silicon carbide raw material filled in the raw material filling portion of the crucible is appropriately used. In the conventional method, it is possible to prevent recrystallization of the silicon carbide raw material in the vicinity of the central axis of the raw material filling portion, which is relatively low in the conventional method. Effective sublimation, that is, the crystallization rate of the silicon carbide raw material [= (weight of grown silicon carbide single crystal ingot) / (weight of filled silicon carbide raw material)] can be increased.

  Further, the method for producing a silicon carbide single crystal ingot of the present invention can produce a silicon carbide single crystal ingot by efficiently sublimating the silicon carbide raw material filled in the raw material filling portion of the crucible, and has a large diameter and a long length. In addition to being suitable for the production of silicon carbide single crystal ingots, the sublimation gas is efficiently and stably supplied to the crystal growth surface of the seed crystal, and the supply of sublimation gas to the crystal growth surface of the seed crystal varies. It is possible to suppress the occurrence of defects due to the fact that a high quality silicon carbide ingot can be manufactured. Moreover, if a silicon carbide single crystal substrate for an electronic material is manufactured using a high quality silicon carbide single crystal ingot manufactured by the method of the present invention, the yield of the substrate manufactured with respect to the silicon carbide raw material is improved. In addition, the cost of the silicon carbide single crystal substrate can be reduced.

FIG. 1 is an explanatory diagram for explaining an apparatus for manufacturing a silicon carbide single crystal ingot according to Embodiment 1 of the present invention. FIG. 2 is an enlarged explanatory view schematically showing the relationship between the crucible, the heat generating member, and the heat insulating material shown in FIG. FIG. 3 is an explanatory diagram for conceptually explaining the non-axisymmetric temperature distribution of the present invention. FIG. 4 is an explanatory view similar to FIG. 2 showing an apparatus for manufacturing a silicon carbide single crystal ingot according to Embodiment 2 of the present invention. FIG. 5 is an explanatory view similar to FIG. 2 showing an apparatus for manufacturing a silicon carbide single crystal ingot according to Embodiment 3 of the present invention. FIG. 6 is an explanatory view similar to FIG. 4 for explaining a state where the crucible of FIG. 5 has moved upward. FIG. 7 is an explanatory diagram for explaining the principle of the improved Rayleigh method.

  Hereinafter, using a silicon carbide single crystal ingot manufacturing apparatus shown in the accompanying drawings, a silicon carbide single crystal ingot manufacturing apparatus of the present invention, and a method of manufacturing a silicon carbide single crystal ingot of the present invention using this manufacturing apparatus, The embodiment will be described.

Embodiment 1
FIG. 1 is a diagram for explaining an apparatus for manufacturing a silicon carbide single crystal ingot according to Embodiment 1 of the present invention. In this apparatus, a graphite crucible 1 made of graphite (hereinafter referred to as a graphite crucible 1) is placed in a double quartz tube 13. And a graphite heat insulating material 5 (5a, 5b) covering the crucible 1 so as to surround the crucible 1. The crucible 1 is composed of a graphite crucible body 1a formed in a cylindrical shape with an upper end opening and a graphite crucible upper lid 1b that closes the upper end opening, and the crucible body 1a has a lower part. Is provided with a raw material filling portion 1c for filling a silicon carbide raw material (hereinafter simply referred to as "raw material") 3, and a seed crystal 2 made of a silicon carbide single crystal is attached to the inner surface of the crucible upper lid 1b. ing. The crucible 1 is disposed on the crucible support 10 and has a function capable of rotating with respect to the double quartz tube 13 by a rotation mechanism (not shown) included in the crucible support 10. The heat insulating material 5 (5a, 5b) surrounding the crucible 1 is composed of a heat insulating material 5a covering the outer peripheral side of the crucible main body 1a and a bottom wall portion of the raw material filling portion 1c below the crucible main body 1a (hereinafter simply referred to as “crucible bottom”). Through a vertical movement drive device 12 for moving the thermal insulation material 5 (5a, 5b) vertically relative to the crucible 1 in a vertical direction. It is supported by a heat insulating material support member 11.

  In FIG. 1, reference numeral 6 indicates a notch hole, reference numeral 13 indicates a double quartz tube, reference numeral 14 indicates a vacuum exhaust device, reference numeral 15 indicates an Ar gas pipe, and reference numeral 16 indicates an Ar gas pipe. A mass flow controller is shown. Reference numeral 17 denotes a work coil for high-frequency induction heating for heating a crucible body 1a of the crucible 1 functioning as a heat-generating member and a heat-generating member 7 described later. A high-frequency current is applied to the work coil 17. A high-frequency power source (not shown) for flowing is attached. The work coil 17 is provided with a vertical movement drive device 18 for moving the vertical movement relative to the crucible 1 in the vertical direction.

In the first embodiment, as shown in FIGS. 1 and 2, both end openings made of the same graphite as the crucible 1 and capable of high-frequency induction heating are formed on the heat insulating material 5b supported by the heat insulating material supporting member 11. A cylindrical heating member 7 is provided. The cylindrical heating member 7 having both ends open is filled with the raw material between the outer peripheral side of the raw material filling part 1c located at the lower part of the crucible body 1a and the heat insulating material 5a covering the outer peripheral side of the raw material filling part 1c. Is located so as to surround the outer periphery of the portion 1c, and the center axis O _{i of the} inner periphery thereof is positioned substantially coincident with the crucible center axis O _{c of the} crucible 1 (the crucible body 1a), The outer peripheral central axis O _o is eccentric from the inner peripheral central axis O _i (or the crucible central axis O _c ), and as a result, the wall thickness of the heat generating member 7 changes along the circumferential direction of the cross section. It has a non-axisymmetric shape.

In the manufacturing apparatus of the first embodiment, the inside of the double quartz tube 13 can be evacuated to a high vacuum (10 ⁻³ Pa or less) by a vacuum exhaust device 14, and an Ar gas pipe 15 and an Ar gas mass flow controller 16. The internal atmosphere can be pressure controlled with Ar gas. The temperature of the crucible 1 is measured by providing an optical path at the center of the graphite heat insulating material 5 covering the upper and lower parts of the crucible 1, and the upper part of the crucible 1 (crucible upper cover 1b) and the lower part (the raw material of the lower part of the crucible body 1a). The light from the bottom wall portion of the filling portion 1c (crucible bottom wall portion)] is taken out and performed using a two-color thermometer, the raw material temperature is judged from the temperature at the bottom of the crucible 1, and from the temperature at the top of the crucible 1 The temperature of the seed crystal 2 is judged.

When the silicon carbide single crystal is grown on the seed crystal 2 using the manufacturing apparatus of the first embodiment, a temperature gradient is formed in the vertical direction inside the crucible 1, and the temperature of the raw material filling portion 1c is set. The temperature of the crystal growth portion of the seed crystal 2 is relatively lowered to lower the temperature, but at this time, the low temperature portion of the raw material 3 filled in the raw material filling portion 1c below the crucible body 1a Because of this, not the conventional crucible central axis O _c where the low temperature portion of the raw material 3 is generated by heating only by the heat generation of the crucible body 1a, but the conventional crucible central axis O _c (that is, the inner circumference of the heating member 7). Is generated at a position shifted from the center axis O _i ).

A conceptual illustration of a state where the low temperature portion of the raw material 3 is shifted to the central axis O _o side of the outer periphery of the heat generating member 7 from the conventional crucible central axis O _c (the central axis O _i of the inner periphery of the heat generating member 7). This is shown in FIG.
That is, in FIG. 2, the temperature distribution in the radial direction of the crucible 1 when focusing only on the crucible body 1a out of the crucible body 1a and the heating member 7 of the manufacturing apparatus that generates heat by high frequency induction heating is the same as that of the conventional manufacturing apparatus. Similarly, the heat generated by the high frequency induction heating at the side wall of the crucible body 1a is discharged from the raw material 3 in the raw material filling portion 1c through the seed crystal 2 to the outside of the system. The temperature in the vicinity of the outer peripheral portion of the raw material 3 is high, the temperature decreases toward the vicinity of the central axis thereof, and a temperature distribution as shown by a one-dot chain line in FIG. 3 is generated in the radial direction of the crucible 1. so that the low temperature portion occur in the O _C near the crucible center axis. In FIG. 2, regarding the temperature distribution in the radial direction of the crucible 1 when focusing only on the heat generating member 7 provided in the manufacturing apparatus, the wall thickness of the heat generating member 7 changes in the circumferential direction of the cross section as described above. Since it has a non-axisymmetric shape, the raw material 3 in the raw material filling portion 1c has a diameter of the crucible 1 different from the temperature distribution shown by the one-dot chain line, for example, as shown by a solid line in FIG. A temperature distribution shifted in the direction will occur. When both the crucible main body 1a and the heat generating member 7 generate heat by high frequency induction heating as in the present invention, the temperature distribution of the one-dot chain line based on the crucible main body 1a and the temperature of the solid line based on the heat generating member 7 are described. The low temperature portion B generated in the raw material 3 in the raw material filling portion 1c overlaps with the distribution, and is in the vicinity of the crucible central axis O _C (that is, the central axis O _i of the inner periphery of the heat generating member 7) when the heat generating member 7 does not exist. Therefore, it is shifted to a position deviated from the position.

In the first embodiment, the crucible 1 is rotated with respect to the heat generating member 7 during crystal growth by using a rotation mechanism (not shown) incorporated in the crucible support 10 shown in FIG. The low temperature part B of the raw material 3 formed at a position deviated from the vicinity of the axis O _C (that is, the central axis O _i of the inner periphery of the heat generating member 7) moves around the axis of the crucible central axis O _C inside the raw material 3. It can be made to. That is rotated around the axis of the crucible center axis O _C using a rotating mechanism of the low temperature section B, by changing the temperature distribution, which heats the low temperature section B to a high temperature, recrystallization at low temperature portion Then, the raw material 3 is heated to a high temperature by the temperature change caused by the subsequent rotation of the crucible, and the raw material 3 is effectively sublimated for use.

[Embodiment 2]
FIG. 4 is an explanatory view similar to FIG. 2 showing an apparatus for manufacturing a silicon carbide single crystal ingot according to Embodiment 2 of the present invention. Unlike Embodiment 1, the heating member 7 has a circular inner periphery. And the central axis is formed at a position coincident with the central axis of the crucible body 1a (crucible central axis), and the outer periphery thereof is formed in an elliptical shape, and the outer peripheral central axis is the center of the inner periphery. It is formed in a non-axisymmetric both-end opening cylindrical shape that is located eccentrically from the axis (crucible central axis).
Also in the manufacturing apparatus of the second embodiment, as in the first embodiment, the wall thickness of the heat generating member 7 has a non-axisymmetric shape that varies along the circumferential direction of the cross section, and the raw material filling portion 1c The low temperature portion generated in the raw material 3 can be shifted to a position deviated from the vicinity of the conventional crucible central axis O _C (that is, the central axis of the inner periphery of the heat generating member 7). used by rotating the low temperature portion around the axis of the crucible center axis O _C, it can be utilized by effectively sublimate material 3.

[Embodiment 3]
5 and 6 are explanatory views similar to FIG. 2 showing an apparatus for producing a silicon carbide single crystal ingot according to Embodiment 3 of the present invention. Unlike Embodiment 1, the heat insulating material 5a includes a crucible. 1 is provided with a vertical movement space S that allows the crucible 1 to move in the vertical direction relative to the heat insulating material 5 (5a, 5b). The vertical movement drive device 12 shown in FIG. The material 5 (5a, 5b) is moved up and down to change the temperature distribution generated in the raw material 3 in the raw material filling portion 1c by high-frequency induction heating so that the raw material 3 can be heated more uniformly.
Also in the manufacturing apparatus of the third embodiment, as in the first embodiment, the wall thickness of the heat generating member 7 has a non-axisymmetric shape that varies along the circumferential direction of the cross section, and the raw material filling portion 1c The low temperature portion generated in the raw material 3 can be shifted to a position deviated from the vicinity of the conventional crucible central axis O _C (that is, the central axis of the inner periphery of the heat generating member 7). used by rotating the low temperature portion around the axis of the crucible center axis O _C, it can be utilized by effectively sublimate material 3.

Here, the non-axisymmetric heat generating member used in the present invention will be described in more detail below.
First, the material of the heat generating member may be any material that is heated by high-frequency induction heating, but is preferably a material that does not introduce impurities into the grown crystal, and is preferably a graphite material similar to the crucible. In addition, the shape of the heat generating member is not limited to the non-axisymmetric both-end opening cylindrical shape in which the wall thickness shown in the first and third embodiments and the second embodiment changes along the circumferential direction of the cross section. The wall member may be divided into a plurality of wall members having different wall thicknesses along the circumferential direction of the cross section, and the plurality of wall members may constitute a cylindrical shape as a whole, and the structure capable of achieving the object of the present invention. The eye is not particularly limited.

  In the present invention, the crucible body upper portion of the crucible preferably has an axially symmetric induced current flowing by high-frequency induction heating to form an axially symmetric heat generation distribution. In the present invention, the heat generating member 7 is provided. The reason for this is to form a non-axisymmetric temperature distribution inside the raw material in the raw material filling section, so the height and installation position of the heating member is the same as or lower than the height of the raw material. It is preferable that the height of the raw material is not less than 0.6 times and not more than 1 time, and the position where the bottom surface of the crucible 1 coincides with the bottom surface of the heating member 7 or from the bottom surface of the crucible 1. It is preferable to set the heat generating member 7 at a low position. If the height of the heat generating member is made higher than the height of the raw material, the temperature distribution of the growing crystal tends to be non-axisymmetric, and there is a possibility that appropriate growth conditions cannot be obtained.

  Furthermore, with respect to the rotation speed when the crucible is rotated with respect to the heat generating member, the crucible body and the heat generating member generate heat, and there is a time enough for the change in temperature distribution generated thereby to be sufficiently reflected as the temperature distribution. The relative rotation speed between the crucible and the heat generating member is preferably 2 to 60 rotations per hour. If it is slower than this rotational speed, the movement of the low temperature part inside the raw material will be slow, and the high temperature part will continue to be heated for a relatively long time, which tends to cause depletion of the sublimation gas, making the raw material effective. There is a possibility that the effect of sublimation cannot be obtained. In addition, when the rotational speed is higher than this, the temperature distribution change caused by the heat generation of the crucible body and the heating member cannot sufficiently affect the temperature distribution, and the non-axisymmetric temperature distribution is caused by the high speed rotation. There is a possibility that the averaged temperature distribution becomes axisymmetric and the effect of the invention cannot be obtained.

The thickness of the heat generating member having a non-axisymmetric shape is desirably determined according to the induction heating frequency used for high frequency induction heating.
In general, when a high frequency is passed through a conductor, the current density is high on the conductor surface due to the interaction with the magnetic field, and decreases as it enters the inside. The thickness at which the surface current density decays to a current density of 1 / e is called the “skin thickness” and is described by d in the following equation.
d = (2 / σωμ) ^1/2
[Where σ: conductivity of conductor, ω: angular velocity of current = 2πf (f: frequency of current), μ: permeability of conductor]

  That is, as the frequency of the high-frequency current increases, the skin thickness d decreases and the high-frequency current concentrates on the surface. Therefore, when the thickness of the heat generating member is sufficiently larger than the skin thickness d, the heat generation near the surface of the heat generating member is not dependent on the thickness of the heat generating member and is uniform in the circumferential direction. Become. In this case, the non-axisymmetric property of the temperature distribution depends only on the non-axisymmetric property of the shape of the heat generating member, and although it can be obtained up to the degree of the non-axisymmetric property of the temperature distribution, the effect is small. When the thickness of the heat generating member is about the same as the skin depth d or thinner than the skin thickness d, the magnetic field penetrates to the crucible inside the heat generating member. At this time, since the current density in the portion where the thickness of the heat generating member is thin increases, heat generation increases. At the same time, heat is generated in the portion where the thickness of the heat generating member is small compared to the portion where the thickness of the heat generating member is thick, and the temperature is increased. For these reasons, the heat generating member has a thin portion having a thickness of 0.1 to 0.8 times the skin thickness d, and a thickness of the thick portion being 1 or more times the skin thickness d. It is preferably 1.5 times or less.

  When a silicon carbide single crystal ingot having a growth height of 40 mm or more and 100 mm or less is manufactured by the manufacturing method of the present invention, the silicon carbide raw material filled in the crucible can be used effectively, so that the crystallization rate is improved. Can be made. Further, the fluctuation of the crystal growth rate during crystal growth is reduced, and a high-quality silicon carbide single crystal can be obtained. For this reason, it becomes possible to produce the silicon carbide single crystal for electronic materials efficiently, and the silicon carbide single crystal ingot can be manufactured at a lower cost.

[Example 1]
In Example 1, the apparatus for manufacturing a silicon carbide single crystal ingot of Embodiment 1 shown in FIGS. 1 and 2 was used. The heat generating member of this manufacturing apparatus is formed of the same graphite material as that of the crucible, and is arranged around the raw material filling portion at the same height as the raw material filling portion. Heat is generated by induction heating.

The heat generating member was 0.9 times as high as the raw material filling portion of the crucible, and was made by using a columnar graphite material and decentering from the central axis and penetrating into a cylindrical shape. The thickness of the thick part is 20 mm, which is 1 times the skin thickness d, and the thickness of the thin part is 10 mm, which is 0.5 times the skin thickness d.
In the raw material filling portion at the lower part of the crucible body, 2.6 kg of silicon carbide raw material made of silicon carbide crystal powder produced by the Atchison method is filled, and the crucible upper lid of the crucible has a diameter of 105 mm as a seed crystal. A 4H polytype silicon carbide single crystal wafer having a (0001) plane was placed.

  As shown in FIG. 1, the component member composed of the crucible and the heat generating member prepared in this way is installed inside a double quartz tube, and crystal growth of a silicon carbide single crystal is performed according to a conventional method according to the above procedure. It was. That is, after raising the raw material temperature to the target temperature of 2300 ° C., the pressure of Ar in the double quartz tube is reduced to a growth pressure of 1.3 kPa over 30 minutes to start the growth of the silicon carbide single crystal, Was continued for 160 hours to grow a silicon carbide single crystal. At this time, the crucible was rotated at a constant speed of 10 rotations / hour with respect to the heating member.

In the production of the silicon carbide single crystal ingot of Example 1, a silicon carbide single crystal ingot having a growth rate of about 0.35 mm / hour, a diameter of about 105 mm, and a height of about 55 mm was obtained. Observation of the residue of the raw material in the crucible confirmed that the raw material was efficiently sublimated even in the vicinity of the crucible central axis of the raw material filling portion, and the heating temperature for the raw material can be effectively changed during high frequency induction heating. As a result, the raw material near the central axis could also be heated efficiently. Further, the weight of the obtained single crystal ingot was about 1.5 kg, and the crystallization rate was 60%.
Furthermore, when the obtained silicon carbide single crystal ingot was analyzed by X-ray diffraction and Raman scattering, it was an ingot consisting of a single polytype of 4H, and it was extremely high quality with few crystal defects such as micropipes. It was confirmed.
The silicon carbide single crystal substrate cut out from the ingot is useful as a substrate for manufacturing an electronic device.

[Example 2]
In Example 2, the height of the heat generating member is 0.6 times the height of the raw material filling portion, the thickness of the thick portion is 28 mm, the skin thickness d is 1.4 times, and the thickness of the thin portion is The thickness is set to 6 mm and the skin thickness d is 0.3 times, and 5.4 kg of silicon carbide raw material is filled in the raw material filling portion at the bottom of the crucible body, and the diameter of the crucible upper lid is a seed crystal. Except that a 4H polytype silicon carbide single crystal wafer having a (0001) surface of 155 mm was disposed, a constituent member including a crucible and a heating member was prepared in the same manner as in Example 1 above.

  As shown in FIG. 1, the component member composed of the crucible and the heat generating member prepared in this way is installed inside a double quartz tube, and crystal growth of a silicon carbide single crystal is performed according to a conventional method according to the above procedure. It was. That is, after raising the raw material temperature to the target temperature of 2300 ° C., the pressure of Ar in the double quartz tube is reduced to a growth pressure of 1.3 kPa over 30 minutes to start the growth of the silicon carbide single crystal, Was continued for 140 hours to grow a silicon carbide single crystal. At this time, the crucible was rotated at a constant speed of 50 rotations / hour with respect to the heat generating member.

In the production of the silicon carbide single crystal ingot of Example 2, a silicon carbide single crystal ingot having a growth rate of about 0.4 mm / hour, a diameter of about 155 mm, and a height of about 56 mm was obtained. Observation of the residue of the raw material in the crucible confirmed that the raw material was efficiently sublimated even in the vicinity of the crucible central axis of the raw material filling portion, and the heating temperature for the raw material can be effectively changed during high frequency induction heating. As a result, the raw material near the central axis could also be heated efficiently. The weight of the obtained single crystal ingot was about 3.4 kg, and the crystallization rate was 63%.
Furthermore, when the obtained silicon carbide single crystal ingot was analyzed by X-ray diffraction and Raman scattering, it was an ingot consisting of a single polytype of 4H, and it was extremely high quality with few crystal defects such as micropipes. It was confirmed.
The silicon carbide single crystal substrate cut out from the ingot is useful as a substrate for manufacturing an electronic device.

Example 3
In Example 3, the silicon carbide single crystal ingot manufacturing apparatus of Embodiment 3 shown in FIGS. 1, 5, and 6 was used. Also in this manufacturing apparatus, the graphite crucible body and the heat generating member generate heat by high-frequency induction heating, as in Examples 1 and 2.

The heat generating member was 0.8 times the height of the raw material filling portion of the crucible, and was made by using a columnar graphite material that was eccentric from the central axis and penetrated into a cylindrical shape. The thickness of the thick portion is 24 mm, which is 1.2 times the skin thickness d, and the thickness of the thin portion is 12 mm, which is 0.6 times the skin thickness d.
The raw material filling portion at the lower part of the crucible body is filled with 7.5 kg of silicon carbide raw material made of silicon carbide crystal powder produced by the Atchison method, and the crucible upper lid of the crucible has a diameter of 155 mm as a seed crystal. A 4H polytype silicon carbide single crystal wafer having a (0001) plane was placed.

  As shown in FIG. 1, the component member composed of the crucible and the heat generating member prepared in this way is installed inside a double quartz tube, and crystal growth of a silicon carbide single crystal is performed according to a conventional method according to the above procedure. It was. That is, after raising the raw material temperature to the target temperature of 2300 ° C., the pressure of Ar in the double quartz tube is reduced to a growth pressure of 1.3 kPa over 30 minutes to start the growth of the silicon carbide single crystal, For 180 hours to grow a silicon carbide single crystal. Further, at this time, the crucible is rotated at a constant speed of 20 rotations / hour with respect to the heat generating member, and the heat generating member is moved from a position higher than the crucible shown in FIG. 5 to a low position shown in FIG. And moved at a speed of 0.02 mm / h.

In the production of the silicon carbide single crystal ingot of Example 3, a silicon carbide single crystal ingot having a growth rate of about 0.45 mm / hour, a diameter of about 155 mm, and a height of about 56 mm was obtained. Observation of the residue of the raw material in the crucible confirmed that the raw material was efficiently sublimated even in the vicinity of the crucible central axis of the raw material filling portion, and the heating temperature for the raw material can be effectively changed during high frequency induction heating. As a result, the raw material near the central axis could also be heated efficiently. The weight of the obtained single crystal ingot was about 4.9 kg, and the crystallization rate was 65%.
Furthermore, when the obtained silicon carbide single crystal ingot was analyzed by X-ray diffraction and Raman scattering, it was an ingot consisting of a single polytype of 4H, and it was extremely high quality with few crystal defects such as micropipes. It was confirmed.
The silicon carbide single crystal substrate cut out from the ingot is useful as a substrate for manufacturing an electronic device.

[Comparative Example 1]
In Comparative Example 1, crystal growth was performed in the same manner as in Example 1 without using the heat generating member and including the arrangement of each member other than the heat generating member.

In the production of the silicon carbide single crystal ingot of Comparative Example 1, a silicon carbide single crystal ingot having a growth rate of about 0.17 mm / hour, a diameter of about 155 mm, and a height of about 16 mm was obtained. Observation of the residue of the raw material in the crucible revealed that the raw material was recrystallized in the vicinity of the central axis of the raw material and was not effectively used for crystal growth. Due to the recrystallization of the sublimation gas in the vicinity of the central axis of the raw material, the supply of the raw material gas was interrupted during the crystal growth, the growth surface of the grown crystal was sublimated, and the growth surface was carbonized. The weight of the obtained single crystal ingot was about 0.4 kg, and the crystallization rate was only 17%.
Furthermore, when the obtained silicon carbide single crystal ingot was analyzed by X-ray diffraction, crystal defects such as micropipes were generated, and it was found that the silicon carbide single crystal ingot was unsuitable for a substrate for producing an electronic device.

DESCRIPTION OF SYMBOLS 1 ... Crucible, 1a ... Crucible body, 1b ... Crucible top cover, 1c ... Raw material filling part, 2 ... Seed crystal, 3 ... Silicon carbide raw material (raw material), 4 ... Single crystal ingot, 5, 5a, 5b ... Insulating material, 6 DESCRIPTION OF SYMBOLS ... Notch hole, 7 ... Heat generating member, 10 ... Crucible support, 11 ... Insulation support member, 12 ... Vertical motion drive device, 13 ... Double quartz tube, 14 ... Vacuum exhaust device, 15 ... Ar gas piping, 16 ... Ar gas mass flow controller, 17 ... work coil, 18 ... vertical drive, Oc ... crucible central axis, O _i ... heat generating member inner peripheral axis, O _o ... heat generating member outer peripheral central axis, B ... Low temperature part, S ... Vertical movement space.

Claims (5)

A raw material filling portion having a graphite crucible main body formed in a cylindrical shape with an upper end opening and a graphite crucible upper lid closing the upper end opening of the crucible main body, and a silicon carbide raw material filled in the lower portion of the crucible main body A silicon carbide single crystal ingot for producing a silicon carbide single crystal by a sublimation recrystallization method, and a work coil disposed outside the crucible and configured to heat the crucible body by high frequency induction heating In the device
Outside the raw material filling portion at the lower part of the crucible body, a heating member that has a non-axisymmetric shape with respect to the central axis of the crucible body and generates heat by high-frequency induction heating by the work coil is disposed. An apparatus for manufacturing a silicon carbide single crystal ingot, comprising: a rotation mechanism that relatively rotates a heat generating member and the crucible body about a central axis of the crucible body.   The heating member is a cylindrical heating member that is disposed so as to surround the outer side of the raw material filling portion at the lower part of the crucible body, and has a non-axisymmetric shape in which an outer peripheral central axis is eccentric with respect to an inner peripheral central axis. The apparatus for producing a silicon carbide single crystal ingot according to claim 1.   3. The apparatus for producing a silicon carbide single crystal ingot according to claim 1, wherein the heating member has a height that is not less than 0.6 times and not more than 1 time with respect to a height of the raw material filling portion.   The relative rotation speed between the said heat generating member and the said crucible main body is 2-60 rotations per hour, The manufacturing apparatus of the silicon carbide single crystal ingot of any one of Claims 1-3 characterized by the above-mentioned. . The silicon carbide raw material filled in the raw material filling portion at the lower part of the graphite crucible body is heated and sublimated, and the generated sublimation gas is regenerated on the surface of the seed crystal composed of a silicon carbide single crystal installed on the inner surface of the crucible upper lid. In the method for producing a silicon carbide single crystal ingot to be crystallized,
A heat generating member capable of high-frequency induction heating having a non-axisymmetric shape with respect to the central axis of the crucible body is disposed outside the raw material filling portion at the lower part of the crucible body, and the heat generating member and the crucible body are connected to the crucible body. The silicon carbide is heated while causing the crucible body and the heat generating member to generate heat by high-frequency induction heating while relatively rotating about the central axis of the material, and forming a non-axisymmetric temperature distribution inside the raw material filling portion A method for producing a silicon carbide single crystal ingot, wherein the raw material is sublimated.

Images