JP2019026499A - Method for manufacturing single crystal - Google Patents

Abstract

To provide a method for surely manufacturing a single crystal having high quality and a large surface size by a simpler method.SOLUTION: A method for manufacturing a single crystal SiC42 includes a pattern formation step and a crystal growth step. In the pattern formation step, a plurality of long-sized piece 41 projected in the c axial direction and long-sized when viewed in the c axial direction are formed at an interval by removing or growing a part of (0001) surface or (000-1) surface of a SiC substrate 40 having a hexagonal system crystal structure. In the crystal growth step, the single crystals SiC42 grown from the long-sized pieces 41 are connected to each other by growing a crystal in a direction vertical to the c axis and in the c axial direction to the SiC substrate 40. In the long-sized pieces 41 formed in the pattern formation step, included are long-sized pieces in which the absolute value of an angle formed of the longitudinal direction when viewed in the c axial direction and the [11-20] direction of the SiC substrate 40 is within a range of 30°+60n°±15°.SELECTED DRAWING: Figure 3

Description

  The present invention mainly relates to a method for producing a single crystal using a substrate having a hexagonal crystal structure.

  Conventionally, a method for producing a single crystal with few defects has been sought in order to produce a high-quality semiconductor device. Patent Documents 1 to 4 disclose techniques for producing single crystal SiC.

  In the method for producing single crystal SiC disclosed in Patent Document 1, first, a plurality of convex portions are provided on a SiC substrate. Thereafter, crystal growth is performed on this convex portion by MSE method (metastable solvent epitaxy method). Thereby, since single-crystal SiC grows so that it may spread in a diameter direction from a convex part, single-crystal SiC whose surface size is larger than a convex part can be manufactured.

  In the method for producing single-crystal SiC disclosed in Patent Document 2, first, a plurality of convex portions are formed by removing the surface of the SiC substrate in a lattice shape with a laser. Thereafter, crystal growth is performed on the SiC substrate by the MSE method. At this time, since the convex portion including TSD has a higher growth rate in the c-axis direction than the convex portion not including TSD, the height in the c-axis direction is increased. After removing the convex portion having a high height in the c-axis direction with a laser, the MSE method is performed again. Thereby, single crystal SiC grown from a plurality of convex portions is connected, and single crystal SiC having a large surface size is manufactured.

  In the method for producing single-crystal SiC disclosed in Patent Document 3, first, a second seed crystal is formed by forming macrostep bunching on the SiC seed crystal. Next, step bunching is formed on the TSD of the second seed crystal. By forming step bunching on the TSD and performing step flow growth, the TSD is converted into stacking faults (defects that do not penetrate the surface of the substrate), so that single-crystal SiC with less TSD is manufactured.

  In Patent Document 4, thin single crystal SiC is cut out from single crystal SiC manufactured by crystal growth on a SiC substrate. Then, crystal growth is performed again on the thin plate-like single crystal SiC. By repeating the above processing, single crystal SiC with a small TSD is manufactured.

JP 2006-298722 A JP 2017-88444 A JP 2014-43369 A Japanese Patent Laid-Open No. 2003-119097

  Among Patent Documents 1 to 4, the MSE method described in Patent Documents 1 and 2 can grow crystals in the direction of increasing the size of the surface, so that propagation of crystal defects such as TSD (through threading dislocation) is unlikely to occur. . Therefore, high quality single crystal SiC can be manufactured. However, in the method of Patent Document 1, in order to manufacture single crystal SiC having a size of a certain size or more, it is necessary to grow the convex portion over a long time. Further, in the method of Patent Document 2, since single crystal SiC grown in the radial direction is not always reliably connected, improvement has been demanded.

  The problem described above is not limited to SiC, and the same problem exists even with other hexagonal substances.

  The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a method for more reliably producing a single crystal having a high quality and a large surface size.

Means and effects for solving the problems

  The problems to be solved by the present invention are as described above. Next, means for solving the problems and the effects thereof will be described.

  According to an aspect of the present invention, the following method for producing a single crystal is provided. That is, this single crystal manufacturing method performs a process including a pattern formation step and a crystal growth step. In the pattern forming step, a part of the (0001) plane or the (000-1) plane of the substrate having a hexagonal crystal structure is removed or a part of the substrate is grown to project in the c-axis direction and c A plurality of long pieces that are long when viewed in the axial direction are formed at intervals. In the crystal growth step, the single crystals grown from the long pieces are connected to each other by performing crystal growth in the direction perpendicular to the c-axis and in the c-axis direction with respect to the substrate. The long piece formed in the pattern forming step has an absolute value of an angle formed by the longitudinal direction when viewed in the c-axis direction and the [11-20] direction of the substrate, and n is zero or more. Those in the range of 30 ° + 60 n ° ± 15 ° as an integer are included.

  Thereby, by forming the long pieces having the above-mentioned angle, the long pieces can be connected to each other in the crystal growth process. Further, even when TSD is present in a portion where the long piece is not formed, the crystal defect does not propagate to the single crystal to be grown, so that a high-quality single crystal can be manufactured.

  In the method for producing a single crystal, the long piece formed in the pattern forming step has an angle formed between a longitudinal direction when viewed in the c-axis direction and a [11-20] direction of the substrate. It is preferable that the absolute value of is in the range of 30 ° + 60 n ° ± 10 °.

  Thereby, by forming the long pieces having the above-mentioned angle, the long pieces can be more reliably connected in the crystal growth step.

  In the method for producing a single crystal, it is preferable that the adjacent long pieces are formed at positions overlapping each other by being moved in any of the <11-20> directions of the substrate.

  Thereby, the adjacent long pieces can be more reliably connected in the crystal growth step.

  In the method for producing a single crystal, in the pattern forming region in which the pattern of the long piece is formed in the pattern forming step, at least one of the long pieces is formed from one end to the other end of the pattern forming region. It is preferable. The pattern formation region may be a part of the substrate or the entire surface of the substrate.

  Thereby, since the connection of the single crystal in directions other than the <11-20> direction is not required, a single crystal having a large surface size can be more reliably manufactured.

  In the method for manufacturing a single crystal, the long piece formed in the pattern forming step has a portion where a positive angle with respect to the [11-20] direction of the substrate is connected to a negative portion. The bent shape is preferable.

  Thereby, unlike the long piece which is not bent, a long piece having the same absolute value of the angle formed from one end of the substrate to the other end can be formed.

  In the method for producing a single crystal, in the pattern forming step, it is preferable to form a plurality of the long pieces by irradiating the substrate with a laser.

  Thereby, a long piece can be formed easily and in a short time as compared with a method of forming a long piece by performing crystal growth on only a part.

  In the method for producing a single crystal, the substrate is preferably a SiC substrate, and the single crystal is preferably single crystal SiC.

  Thereby, high quality single crystal SiC can be manufactured by a simple process.

  In the method for producing a single crystal, in the crystal growth step, a Si melt exists between the SiC substrate and a feed material having higher free energy than that of the SiC substrate and supplying at least C. It is preferable to perform a metastable solvent epitaxy method in which the single crystal SiC is grown on the surface of the SiC substrate by heating at a temperature of 1.

  Thereby, since the metastable solvent epitaxy method has a high growth rate in the direction perpendicular to the c-axis, single crystal SiC grown from a long piece can be connected in a short time.

The figure explaining the outline | summary of the high temperature vacuum furnace used with the manufacturing method etc. of the single crystal SiC of this invention. The schematic diagram which shows the manufacturing process (a pattern formation process and a damage removal process) of single crystal SiC. The schematic diagram which shows the manufacturing process (crystal growth process) of single crystal SiC. The top view explaining the angle | corner (theta) and the pattern formed in a SiC substrate (The figure seen in the c-axis direction). The schematic diagram which shows the crystal growth process by MSE method. The figure which shows TSD distribution of the SiC substrate before crystal growth, and TSD distribution of the SiC substrate after crystal growth. The microscope picture which shows the angle | corner (theta) and the growth state and connection state of a single crystal. The schematic diagram which shows angle | corner (theta) and the growth state and connection state of a single crystal. The figure which shows another example which the growth stopped by formation of the {1-100} facet surface. The figure which shows the direction (crystal orientation) in the (0001) plane of a hexagonal crystal structure. The schematic diagram which shows the other pattern formed in a SiC substrate.

  Next, embodiments of the present invention will be described with reference to the drawings. First, with reference to FIG. 1, the high temperature vacuum furnace 10 used with the manufacturing method of the single crystal SiC of this embodiment, etc. is demonstrated.

  As shown in FIG. 1, the high-temperature vacuum furnace 10 includes a main heating chamber 21 and a preheating chamber 22. The main heating chamber 21 heats a single crystal SiC substrate (hereinafter, SiC substrate 40) having at least a surface made of single crystal SiC (for example, 4H—SiC or 6H—SiC) to a temperature of 1000 ° C. or higher and 2300 ° C. or lower. be able to. The preheating chamber 22 is a space for performing preheating before the SiC substrate 40 is heated in the main heating chamber 21.

  A vacuum forming valve 23, an inert gas injection valve 24, and a vacuum gauge 25 are connected to the main heating chamber 21. The vacuum forming valve 23 can adjust the degree of vacuum of the main heating chamber 21. The inert gas injection valve 24 can adjust the pressure of the inert gas in the main heating chamber 21. In the present embodiment, the inert gas is a gas of a group 18 element (rare gas element) such as Ar, for example, a gas that is poor in reactivity with solid SiC, and is a gas excluding nitrogen gas. . The vacuum gauge 25 can measure the degree of vacuum in the main heating chamber 21.

  A heater 26 is provided inside the main heating chamber 21. A heat reflecting metal plate (not shown) is fixed to the side wall and the ceiling of the main heating chamber 21, and this heat reflecting metal plate reflects the heat of the heater 26 toward the center of the main heating chamber 21. It is configured. Thereby, SiC substrate 40 can be heated strongly and evenly, and the temperature can be raised to a temperature of 1000 ° C. or higher and 2300 ° C. or lower. As the heater 26, for example, a resistance heating type heater or a high frequency induction heating type heater can be used.

  High-temperature vacuum furnace 10 heats SiC substrate 40 accommodated in crucible (accommodating container) 30. The storage container 30 is mounted on an appropriate support base or the like, and is configured to be movable at least from the preheating chamber to the main heating chamber by moving the support base. The storage container 30 includes an upper container 31 and a lower container 32 that can be fitted to each other. The SiC substrate 40 is supported by a support base 33 placed on the lower container 32 of the storage container 30.

The storage container 30 includes a tantalum layer (Ta) and a tantalum carbide layer (TaC and TaC) in order from the external side to the internal space side in the portion constituting the wall surface (upper surface, side surface, and bottom surface) of the internal space in which the SiC substrate 40 is stored. Ta ₂ C) and a tantalum silicide layer (TaSi ₂ or Ta ₅ Si ₃ or the like).

  This tantalum silicide layer supplies Si to the internal space of the container 30 by heating. Further, since the container 30 includes a tantalum layer and a tantalum carbide layer, surrounding C vapor can be taken in. Thereby, the inside space can be made into a high purity Si atmosphere during heating. Instead of providing the tantalum silicide layer, a solid Si source such as Si may be disposed in the internal space. In this case, solid Si sublimates during heating, so that the interior space can be under a high-purity Si vapor pressure.

  When heating the SiC substrate 40, first, as shown by the chain line in FIG. 1, the container 30 is placed in the preheating chamber 22 of the high-temperature vacuum furnace 10 and preliminarily maintained at an appropriate temperature (for example, about 800 ° C.). Heat. Next, the container 30 is moved to the main heating chamber 21 that has been heated to a preset temperature (for example, about 1800 ° C.) in advance. Thereafter, SiC substrate 40 is heated while adjusting the pressure and the like. Note that preheating may be omitted.

  Next, the manufacturing process of the single crystal SiC 42 performed in this embodiment will be described with reference to FIGS. 2 and 3 are schematic views showing a manufacturing process of the single crystal SiC 42.

  As shown in FIGS. 2 and 3, TSD (TSD: threading thread dislocation) is generated in the SiC substrate 40. TSD is a crystal defect in which a crystal displacement direction (Burgers vector) and dislocation lines are parallel. The TSD propagates to the single crystal SiC 42 during crystal growth, thereby reducing the quality of the single crystal SiC 42. In the following description, the TSD generated in the SiC substrate 40 is described with reference numeral 51. Although a large number of TSDs are actually formed on the SiC substrate 40, only one TSD 51 is shown in FIGS. 2 and 3 for the sake of simplicity.

  The SiC substrate 40 used in the present embodiment is an on substrate that does not have an off angle, but may have an off angle. The crystal polymorph of the SiC substrate 40 is 4H—SiC, but other crystal polymorphs (6H—SiC, etc.) may be used. The main surface (surface to be processed) of SiC substrate 40 is the Si surface (0001) surface, but may be the C surface (000-1) surface. Further, the SiC substrate 40 has no projections or the like before the pattern formation step, and has a flat surface.

  First, as shown in FIG. 2A and FIG. 2B, a pattern forming process is performed on the SiC substrate 40. The pattern forming process is a process of forming a pattern composed of a plurality of long pieces 41 on the surface of the SiC substrate 40. In the present embodiment, a pattern is formed by irradiating the SiC substrate 40 with a laser to remove a part of the SiC substrate 40 (a portion where the long piece 41 is not formed).

  Hereinafter, the pattern formed in the present embodiment will be described. The long piece 41 constituting this pattern protrudes from the surface of the SiC substrate 40 in the c-axis direction (in the present embodiment, the [0001] direction). In the present embodiment, the surface of the SiC substrate 40 and the side surface of the long piece 41 are orthogonal to each other, but may have different angles. The length (height) of the long pieces 41 in the c-axis direction is preferably the same for all the long pieces 41, but may be slightly different.

  Further, the long piece 41 has a long shape when viewed in the c-axis direction (that is, a plan view of FIG. 4 and the like). The long shape is an elongated shape, in other words, a shape having a concept of “longitudinal direction”. In the present embodiment, a bent long piece 41 is formed. Specifically, as shown in FIG. 4, one long piece 41 has a portion where the angle formed with respect to the [11-20] direction is + θ and the angle formed with respect to the [11-20] direction is −. This is a configuration in which the θ portion is connected. In addition, the method of calculating | requiring the angle | corner which makes | forms is calculated | required by making a counterclockwise rotation seeing in the c-axis direction positive with respect to the [11-20] direction, and making clockwise rotation negative. A preferable range of the angle θ formed will be described later.

  In the present embodiment, the long pieces 41 having the above-described shape are arranged at predetermined intervals in the [11-20] direction. In other words, by moving a certain long piece 41 in the [11-20] direction, it overlaps with the adjacent long piece 41. The intervals at which the long pieces 41 are formed are preferably the same, but may be different. One long piece 41 is formed from one end to the other end of the SiC substrate 40 (from one end to the other end in the [1-100] direction). In other words, the long pieces 41 are arranged side by side only in the [11-20] direction, and are not arranged side by side in another direction (such as the [1-100] direction). In addition, another example of the pattern of the long piece 41 will be described later.

  In the present embodiment, the pattern of the long piece 41 is formed by irradiating the SiC substrate 40 with a laser, but other methods may be used as long as the pattern of the long piece 41 can be formed. For example, a mask in which an opening is formed in a portion other than the pattern of the long piece 41 is placed on the surface of the SiC substrate 40, and etching (dry etching using fluorine plasma or wet etching such as KOH etching) is performed. Etc.). Thereby, the pattern of the long piece 41 can be formed. Alternatively, the pattern of the long pieces 41 can be formed by growing a part of the SiC substrate 40 instead of removing the SiC substrate 40. Specifically, a mask in which an opening is formed at a position where the pattern of the long piece 41 is formed is placed on the surface of the SiC substrate 40, and crystal growth (solution growth or vapor phase growth or the like) is performed. Thereby, the pattern of the long piece 41 can be formed.

  Next, as shown in FIGS. 2B and 2C, a damage removing process is performed on the SiC substrate 40. The damage removing step is a step of removing damage generated on the surface of the SiC substrate 40 in the pattern forming step. In this embodiment, the damage removal step is performed by Si vapor pressure etching.

Here, the Si vapor pressure etching will be described in detail. In the Si vapor pressure etching, the SiC substrate 40 is housed in the housing container 30, and the Si source described above is present in the housing container 30 (and in a state where elements other than Si and inert gas are not actively supplied). Heating is performed using the high-temperature vacuum furnace 10 in a temperature range of 1500 ° C. to 2200 ° C., preferably 1600 ° C. to 2000 ° C. Thereby, the inside of container 30 is under high-purity Si vapor pressure, and SiC substrate 40 is heated in this state. Thereby, the surface of the outer peripheral surface of SiC substrate 40 is etched and the surface is flattened. In this Si vapor pressure etching, the following reaction is performed. Briefly, when the SiC substrate 40 is heated under Si vapor pressure, the SiC of the SiC substrate 40 is sublimated as Si ₂ C or SiC _{2 due} to thermal decomposition and chemical reaction with Si, and the Si atmosphere. The lower Si is bonded to C on the surface of the outer peripheral surface of the SiC substrate 40 to cause self-organization and flattening.
(1) SiC (s) → Si (v) I + C (s) I
(2) 2SiC (s) → Si (v) II + SiC 2 (v)
(3) SiC (s) + Si (v) I + II → Si ₂ C (v)

  By performing the Si vapor pressure etching, it is possible to remove the damage caused in the pattern forming process. Further, it is possible to remove processing damage (for example, processing damage generated during cutting and polishing) generated when the SiC substrate 40 is manufactured. In this embodiment, the damage removal process is performed using Si vapor pressure etching. However, the pattern formation process may be performed by other methods (for example, dry etching such as hydrogen etching or wet etching such as KOH etching). The damage that has occurred may be removed.

  Next, as shown in FIGS. 3D to 3F, a crystal growth step is performed on the SiC substrate 40. In the crystal growth step, crystal growth is performed on the SiC substrate 40 in the direction perpendicular to the c-axis (horizontal direction, direction perpendicular to the substrate thickness direction, direction of expanding the area) and c-axis direction (substrate thickness direction). The single crystal SiC 42 grown from the long pieces 41 are connected to each other. In the present embodiment, single crystal SiC (epitaxial layer) is grown using MSE method (metastable solvent epitaxy method) which is one of the solution growth methods.

  In this embodiment, the crystal growth process is performed using the MSE method, but other methods (for example, a vapor phase growth method such as a CVD method, a solution growth in which C or the like in a solution is moved by providing a temperature gradient). Or the like) may be used. When the CVD method is used, it is necessary to form an off angle in the SiC substrate 40.

  Hereinafter, the MSE method will be described with reference to FIG. FIG. 4 is a schematic diagram showing a crystal growth process by the MSE method. As shown in FIG. 5, in the present embodiment, the SiC substrate 40 is stored in the storage container 30. In addition to the SiC substrate 40, an Si plate 61 and a feed material 62 are disposed inside the storage container 30. These are supported by a support base 33.

  The SiC substrate 40 is used as a substrate (seed side) for liquid phase epitaxial growth. An Si plate 61 is disposed on one side (upper side) of the SiC substrate 40. The Si plate 61 is a plate-shaped member made of Si. Since the melting point of Si is about 1400 ° C., the Si plate 61 is melted by heating in the high-temperature vacuum furnace 10 described above. A feed material 62 is disposed on one side (upper side) of the Si plate 61. The feed material 62 is made of, for example, polycrystalline 3C—SiC and has a higher free energy than the SiC substrate 40.

  When the SiC substrate 40, the Si plate 61, and the feed material 62 are arranged and heated as described above, the Si plate 61 disposed between the SiC substrate 40 and the feed material 62 is melted, and the silicon melt causes the carbon to melt. Acts as a solvent for transfer. In addition, it is preferable that heating temperature is 1500 degreeC or more and 2300 degrees C or less, for example. Due to this heating, a concentration gradient is generated in the Si melt based on the difference in free energy between the SiC substrate 40 and the feed material 62, and this concentration gradient serves as a driving force to transfer Si from the feed material 62 to the Si melt. C elutes. C taken into the Si melt is combined with Si in the Si melt, and is deposited on the SiC substrate 40 as single crystal SiC. As described above, single-crystal SiC 42 can be grown on the surface of SiC substrate 40. In the MSE method, crystal growth can be performed even when the off-angle is not formed in the SiC substrate 40.

  In the MSE method, crystal growth is performed in a direction perpendicular to the c-axis and in the c-axis direction. Therefore, as shown in FIG. 3E, single crystal SiC 42 is deposited on the long piece 41 of the SiC substrate 40 by crystal growth by performing the MSE method on the SiC substrate 40 on which the long piece 41 is formed. As this single crystal SiC 42 grows in a direction perpendicular to the c-axis (particularly in the a-axis direction), the single crystal SiC 42 grown from adjacent long pieces 41 are connected to each other as shown in FIG. . As described above, single crystal SiC 42 having a large surface size can be manufactured.

  Here, in the portion where the long piece 41 is not formed, the distance to the feed material 62 becomes long, so the growth rate is slow or the crystal does not grow. Therefore, the portion of TSD 51 where the long piece 41 is not formed does not propagate to the single crystal SiC 42. Therefore, single crystal SiC 42 having a low TSD density can be manufactured.

  The single crystal SiC 42 produced as described above can be used as a seed crystal for producing a SiC ingot. Alternatively, the SiC substrate 40 with the single crystal SiC 42 can be used as a SiC wafer for manufacturing a semiconductor device.

  Hereinafter, an experiment for confirming that the TSD density is lowered by manufacturing the single crystal SiC 42 by the method of the present embodiment will be described with reference to FIG. FIG. 6A and FIG. 6B are photographs in which the surface of the SiC substrate 40 is imaged with a microscope after performing a process of visualizing the portion where the TSD 51 is generated on the SiC substrate 40. In FIG. 6A and FIG. 6B, processing is performed so that the portion where the TSD 51 occurs is a black circle. 6A shows the distribution of TSD 51 of SiC substrate 40 before crystal growth, and FIG. 6B shows the distribution of TSD 51 of SiC substrate 40 after crystal growth. As shown in FIGS. 6A and 6B, it can be confirmed that the number of TSDs 51 is greatly reduced by performing crystal growth.

Next, an experiment for confirming the conditions for connecting adjacent single crystal SiC 42 in the crystal growth step will be described with reference to FIGS. In this experiment, a plurality of SiC substrates 40 were prepared, the long pieces 41 having the different angles θ were formed on each SiC substrate 40, and crystal growth was performed on each SiC substrate 40 by the MSE method. The long piece 41 was formed using a Keyence laser device (MD-T1000). The laser medium was Nd: YVO ₄ and the laser wavelength was 532 nm.

  The micrograph shown in FIG. 7 was taken with an SEM using the following characteristics of a hexagonal crystal structure such as SiC. That is, the stacking orientation of single crystal SiC (the direction in which molecular layers made of Si and C are stacked) is folded back in the <1-100> direction or the opposite direction every half cycle. When the stacking orientation on the surface of the single crystal SiC and the angle of the incident electron beam are close, a strong secondary electron beam is generated, and the stacking orientation on the surface of the single crystal SiC and the angle of the incident electron beam are When it is far away, a weak secondary electron beam is generated.

  7 and 8 are diagrams showing the results of this experiment. FIG. 7 shows a micrograph before the crystal growth step and a microphotograph after the crystal growth for each SiC substrate 40 having different angles θ. FIG. 8 shows a schematic diagram after crystal growth. Note that in FIG. 8C, the angles with the same growth (θ = ± 75 °, ± 80 °, ± 85 °) are shown in the same figure, and therefore the magnitude of θ and the schematic diagram There is a slight difference in angle.

  As shown in FIGS. 7 and 8, when the absolute value of the angle θ formed is 55 ° or 60 °, the growth of the single crystal SiC 42 from the long piece 41 in the [11-20] direction becomes non-uniform. In addition, once the {1-100} facet plane is generated in the direction opposite to [11-20], the crystal growth rate is reduced and almost no crystal growth is observed. Therefore, the single crystal SiC 42 are not completely connected to each other, and a gap is generated in part. This gap is not filled even when single crystal SiC 42 is grown for some time.

  On the other hand, when the absolute value of the angle θ formed is 75 °, 80 °, 85 °, 90 °, the single crystal SiC 42 from the long piece 41 grows uniformly in the [11-20] direction and the opposite direction. Occurs. Further, the single crystal SiC 42 grown from the adjacent long pieces 41 is connected without a gap without generating a {1-100} facet plane. Therefore, when the absolute value of the angle θ formed is not less than 75 ° and not more than 90 ° (preferably not less than 80 ° and not more than 90 °), the single crystal SiC 42 can be more reliably connected.

  FIG. 9 is a diagram showing another example in which the growth is stopped by forming the {1-100} facet plane. FIG. 9A shows a schematic diagram before and after growth, and FIG. 9B shows a micrograph after growth. The pattern of the long pieces 41 shown in FIG. 9 has an angle θ of 90 °, but the adjacent long pieces 41 do not overlap even if they are moved in the [11-20] direction. In this case, a {1-100} facet surface may be formed on the short side of the long piece 41 in the growth process of FIG. In this case, the growth stops at this facet surface, and the gap on the short side of the long piece 41 is not filled even when the single crystal SiC 42 is grown over a certain period of time. Thus, in order to connect the single crystal SiC 42 grown from the long piece 41, it is necessary to prevent the formation of the {1-100} facet plane. In addition, when a {1-100} facet plane is formed, there is a high possibility that crystal defects will occur even if single crystal SiC 42 is connected.

  Here, a hexagonal crystal structure such as SiC has a six-fold symmetry in the (0001) plane or the (000-1) plane (that is, when viewed in the c-axis direction). Therefore, even when the crystal is rotated by 60 ° about the c-axis direction as the rotation axis, it has almost the same property. FIG. 10 shows the direction (crystal orientation) in the (0001) plane of the hexagonal crystal structure. Since the hexagonal crystal structure is six-fold symmetric, there are a total of six directions equivalent to the [11-20] direction (that is, the <11-20> direction), and the direction equivalent to the [1-100] direction. There are also a total of 6 (ie, <1-100> directions) (see FIG. 10 for details).

  The {1-100} facet surface described above occurs when the longitudinal direction of the long piece is in the <11-20> direction. Therefore, it is considered that the {1-100} facet surface is less likely to occur as it is closer to the <1-100> direction, which is away from the <11-20> direction. Here, according to the experiment shown in FIGS. 7 and 8, it was confirmed that the difference angle with respect to the [−1100] direction is preferably 15 ° or less, and more preferably 10 ° or less.

  From the above, it can be seen that the difference angle from the <1-100> direction is preferably 15 ° or less, and more preferably 10 ° or less. In other words, using the angle θ formed as described above, in the case where n is an integer greater than or equal to zero, it is preferably within the range of θ = 30 ° + 60n ° ± 15 ° (that is, 30 ° + 60n−15). ° ≦ θ ≦ 30 ° + 60n + 15 °). Further, it is more preferable that the angle is within the range of θ = 30 ° + 60n ° ± 10 ° (that is, 30 ° + 60n−10 ° ≦ θ ≦ 30 ° + 60n + 10 °). Further, in FIG. 10, six examples of more preferable angle ranges are shown by broken lines.

  Moreover, in the said embodiment, although the polygonal long piece 41 is formed, you may form the linear long piece 41 as shown to Fig.11 (a). Further, in the case of forming the broken line-shaped long piece 41, the number of bending may be two or more.

  In the above embodiment, one long piece 41 is formed from one end to the other end of the SiC substrate 40 (from the end on the base side in the [1-100] direction to the end on the front side). As shown in FIG. 11B, long pieces 41 divided in the [1-100] direction may be formed.

  Moreover, in the said embodiment, although the elongate piece 41 is formed to the edge part of the SiC substrate 40, as shown in FIG.11 (c), the elongate piece 41 is located in the position which avoided the edge part of the SiC substrate 40. FIG. May be formed. In this case, a region where the long piece 41 is formed is referred to as a pattern formation region. Further, in the example shown in FIG. 11C, one long piece 41 is formed from one end to the other end of the pattern formation region.

  In the above embodiment, the long pieces 41 having the same shape are formed, but at least one shape (for example, the length of the long piece 41 and the angle θ formed) may be different.

  As described above, in the method for manufacturing single-crystal SiC 42 according to this embodiment, processing including the pattern formation step and the crystal growth step is performed. In the pattern forming process, by removing or growing a part of the (0001) plane or the (000-1) plane of the SiC substrate 40 having a hexagonal crystal structure, the pattern is projected in the c-axis direction. A plurality of long pieces 41 that are long when viewed in the c-axis direction are formed at intervals. In the crystal growth step, the single crystal SiC 42 grown from the long pieces 41 is connected to each other by performing crystal growth in the direction perpendicular to the c axis and in the c axis direction on the SiC substrate 40. In the long piece 41 formed in the pattern forming step, the absolute value of the angle formed by the longitudinal direction when viewed in the c-axis direction and the [11-20] direction of the SiC substrate 40 is n equal to or greater than zero. Those in the range of 30 ° + 60 n ° ± 15 ° as an integer are included.

  Thereby, by forming the long pieces 41 having the above-mentioned angles, the long pieces 41 can be connected to each other in the crystal growth process. Even if the TSD 51 is present in a portion where the long piece 41 is not formed, the crystal defect does not propagate to the single crystal SiC 42 to be grown, and thus high quality single crystal SiC 42 can be manufactured. In addition, when crystal growth is not performed in the pattern formation process as in the present embodiment, single crystal SiC 42 can be manufactured by one crystal growth, and thus a single crystal having a high quality and a large surface size can be obtained by a simple process. SiC 42 can be manufactured.

  Moreover, in the manufacturing method of the single crystal SiC 42 of the present embodiment, the long piece 41 formed in the pattern forming step includes the longitudinal direction when viewed in the c-axis direction, the [11-20] direction of the SiC substrate 40, and , The absolute value of the angle formed by is in the range of 30 ° + 60 n ° ± 10 °.

  Thereby, by forming the long pieces 41 having the above angles, the long pieces 41 can be more reliably connected to each other in the crystal growth step.

  Moreover, in the manufacturing method of the single crystal SiC 42 of the present embodiment, the adjacent long pieces 41 are formed at positions overlapping each other by being moved in any of the <11-20> directions of the SiC substrate 40.

  Thereby, the adjacent long pieces 41 can be more reliably connected in the crystal growth step.

  Further, in the method for manufacturing single-crystal SiC 42 of the present embodiment, in the pattern formation region in which the pattern of the long piece 41 is formed in the pattern formation step, at least one long piece 41 has the other end from the one end of the pattern formation region. Is formed.

  This eliminates the need for connection of single crystal SiC 42 in directions other than the <11-20> direction, so that single crystal SiC 42 having a large surface size can be more reliably manufactured.

  Moreover, in the manufacturing method of the single crystal SiC 42 of the present embodiment, the long piece 41 formed in the pattern forming step has a positive angle with respect to the [11-20] direction of the SiC substrate 40 and a negative portion. It is a bent shape in which the parts are connected.

  Thereby, unlike the long piece 41 which is not bent, the long piece 41 having the same shape can be formed from one end of the SiC substrate 40 to the other end.

  Further, in the method for manufacturing single-crystal SiC 42 of the present embodiment, in the pattern forming step, a plurality of long pieces 41 are formed by irradiating the SiC substrate 40 with a laser.

  Thereby, the long piece 41 can be formed easily and in a short time as compared with the method of forming the long piece 41 by performing crystal growth on only a part thereof.

  Further, in the method for manufacturing single-crystal SiC 42 according to the present embodiment, in the crystal growth step, Si fusion is performed between the SiC substrate 40 and the feed material 62 having higher free energy than that of the SiC substrate 40 and supplying at least C. A metastable solvent epitaxy method for growing single crystal SiC 42 on the surface of the SiC substrate 40 by heating in the presence of the liquid is performed.

  Thereby, since the metastable solvent epitaxy method has a high growth rate in the direction perpendicular to the c-axis, the single crystal SiC 42 grown from the long piece 41 can be connected in a short time.

  The preferred embodiment of the present invention has been described above, but the above configuration can be modified as follows, for example.

  The manufacturing process described with reference to FIGS. 2 and 3 is an example, and the order of the processes can be changed, some processes can be omitted, and other processes can be added. For example, the damage removal step can be omitted.

  The temperature conditions and pressure conditions described above are examples and can be changed as appropriate. Further, a heating device other than the above-described high-temperature vacuum furnace 10 (for example, a high-temperature vacuum furnace having a plurality of internal spaces) is used, a polycrystalline substrate is used as the SiC substrate, or a container having a shape or material different from that of the container 30 is used. You may do it.

  In the present embodiment, the example in which the present invention is applied to the SiC substrate has been described, but the present invention can also be applied to a sapphire substrate, an aluminum nitride substrate, and the like, which are similar hexagonal substrates.

10 High-temperature vacuum furnace 40 SiC substrate 41 Long piece 42 Single crystal SiC

Claims (8)

When a part of the (0001) plane or (000-1) plane of the substrate having a hexagonal crystal structure is removed or a part thereof is grown, when protruding in the c-axis direction and viewed in the c-axis direction A pattern forming step of forming a plurality of long pieces that are long and spaced apart,
A crystal growth step of connecting the single crystals grown from the long pieces by crystal growth in a direction perpendicular to the c-axis and c-axis direction with respect to the substrate;
Process including
The long piece formed in the pattern forming step has an absolute value of an angle formed by the longitudinal direction when viewed in the c-axis direction and the [11-20] direction of the substrate, and n is zero or more. What is contained in the range of 30 degrees +60 n degrees +/- 15 degrees as an integer is included, The manufacturing method of the single crystal characterized by the above-mentioned. A method for producing a single crystal according to claim 1,
The long piece formed in the pattern forming step has an absolute value of an angle formed by the longitudinal direction when viewed in the c-axis direction and the [11-20] direction of the substrate is 30 ° + 60 n ° ±. A method for producing a single crystal, which is within a range of 10 °. A method for producing a single crystal according to claim 1 or 2,
The adjacent long pieces are formed in positions overlapping each other by moving in any of the <11-20> directions of the substrate. A method for producing a single crystal according to any one of claims 1 to 3,
In the pattern formation region in which the pattern of the long piece is formed in the pattern forming step, at least one of the long pieces is formed from one end to the other end of the pattern formation region. Production method. A method for producing a single crystal according to any one of claims 1 to 4,
The long piece formed in the pattern forming step has a bent shape in which a positive part and a negative part are connected to a [11-20] direction of the substrate. A method for producing a single crystal. A method for producing a single crystal according to any one of claims 1 to 5,
In the pattern formation step, a plurality of the long pieces are formed by irradiating the substrate with a laser. A method for producing a single crystal according to any one of claims 1 to 6,
The method for producing a single crystal, wherein the substrate is a SiC substrate, and the single crystal is single crystal SiC. A method for producing a single crystal according to claim 7,
In the crystal growth step, the SiC substrate is heated in a state in which a Si melt exists between the SiC substrate and a feed material having higher free energy than that of the SiC substrate and supplying at least C. A method for producing a single crystal, comprising performing a metastable solvent epitaxy method for growing the single crystal SiC on a surface.