WO2018062224A1 - PROCÉDÉ DE PRODUCTION D'UN MONOCRISTAL DE SiC, ET GERME DE SiC - Google Patents

PROCÉDÉ DE PRODUCTION D'UN MONOCRISTAL DE SiC, ET GERME DE SiC Download PDF

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WO2018062224A1
WO2018062224A1 PCT/JP2017/034852 JP2017034852W WO2018062224A1 WO 2018062224 A1 WO2018062224 A1 WO 2018062224A1 JP 2017034852 W JP2017034852 W JP 2017034852W WO 2018062224 A1 WO2018062224 A1 WO 2018062224A1
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crystal
sic
single crystal
sic single
solution
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PCT/JP2017/034852
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English (en)
Japanese (ja)
Inventor
楠　一彦
和明 関
岸田　豊
晃治 森口
信宏 岡田
宏志 海藤
寛典 大黒
雅喜 土井
幹尚 加渡
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トヨタ自動車株式会社
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Priority to JP2018542615A priority Critical patent/JPWO2018062224A1/ja
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    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B19/00—Liquid-phase epitaxial-layer growth
    • C30B19/12—Liquid-phase epitaxial-layer growth characterised by the substrate
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/36—Carbides

Definitions

  • the present invention relates to a method for producing a SiC single crystal and a SiC seed crystal, and more particularly to a method for producing a SiC single crystal by a solution growth method and a SiC seed crystal used in the solution growth method.
  • SiC single crystal is a thermally and chemically stable compound semiconductor.
  • the SiC single crystal has excellent physical properties as compared with the Si single crystal.
  • a SiC single crystal has a large band gap, a high breakdown voltage, and a high thermal conductivity, and has a high electron saturation rate compared to a Si single crystal. For this reason, SiC single crystals are attracting attention as next-generation semiconductor materials.
  • a sublimation recrystallization method (hereinafter also referred to as a sublimation method), a solution growth method (hereinafter also referred to as a solution method), and the like are known.
  • a SiC single crystal is grown by supplying a raw material to a SiC seed crystal in a gas phase state.
  • the SiC seed crystal is brought into contact with the Si—C solution to grow a SiC single crystal on the SiC seed crystal.
  • a raw material containing Si is put in a crucible and melted to produce a Si—C solution.
  • a SiC single crystal is manufactured by bringing the SiC seed crystal into contact with the Si—C solution and supercooling the Si—C solution in the vicinity of the SiC seed crystal.
  • the Si—C solution refers to a solution in which carbon (C) is dissolved in a melt of Si or Si alloy.
  • the SiC single crystal has two regions having different physical properties, that is, a facet region and a non-facet region.
  • the facet region means a region where a growth interface at the time of crystal growth coincides with a specific crystal plane.
  • the non-faceted area is an area different from the facet area. That is, the non-faceted region means a region where the growth interface at the time of crystal growth does not coincide with the crystal plane.
  • the present invention is not limited to the above definition, and facet regions and non-facet regions are variously defined in each technical field as disclosed in the following patent documents.
  • Patent Document 1 Japanese Patent Application Laid-Open No. 2012-250897
  • Patent Document 2 Japanese Patent Application Laid-Open No. 2013-87005
  • Patent Document 3 Japanese Patent Application Laid-Open No. 2013-100217
  • Patent Document 1 defines a facet region as a region formed by spiral growth. Patent Document 1 further defines a non-faceted region (non-faceted region) as a region formed by step flow growth.
  • a single crystal having both a facet region and a non-facet region is grown by a sublimation method. By removing only the facet region or non-facet region from the grown single crystal, a homogeneous single crystal is obtained.
  • Patent Document 1 discloses that in-plane variation in physical properties of a substrate cut out from a single crystal can be suppressed.
  • Patent Document 2 and Patent Document 3 define a facet region as a high-concentration nitrogen region in which the nitrogen concentration is higher than other regions.
  • a single crystal having both a facet region and a non-facet region is grown by a sublimation method. At this time, the growth is performed so that the facet region is located at the center of the single crystal. The outer periphery of the grown single crystal is ground.
  • Patent Document 2 and Patent Document 3 disclose that a substrate having a full facet region with excellent uniformity of characteristics can be obtained.
  • the SiC single crystal manufactured using the solution method has fewer crystal defects than the SiC single crystal manufactured using the sublimation method. Therefore, for the purpose of reducing crystal defects, a method for producing an SiC single crystal by a solution method rather than a sublimation method has been studied frequently.
  • solvent inclusion refers to a defect caused by the Si—C solution being confined inside the SiC single crystal.
  • Solvent inclusion is a phenomenon that has not been a problem in the sublimation method without using a Si-C solution. If solvent inclusion occurs, the quality of the SiC single crystal is degraded.
  • Patent Document 4 proposes a technique for suppressing the occurrence of solvent inclusion in a solution method.
  • Patent Document 4 is characterized in that the Si—C solution is stirred by periodically changing the rotation speed or the rotation speed and the rotation direction of the crucible during the crystal growth of the SiC single crystal.
  • Patent Document 4 describes that even if the diameter is 1 inch or more and the thickness is as large as 5 microns or more, a high-quality SiC single crystal without inclusion can be produced at a high crystal growth rate.
  • An object of the present invention is to provide a method for producing a SiC single crystal by a solution growth method and a SiC seed crystal used for the solution growth method, which can suppress the occurrence of solvent inclusion.
  • the manufacturing method of the SiC single crystal according to the present embodiment is a manufacturing method by a solution growth method.
  • the SiC single crystal is grown by bringing the crystal growth surface of the SiC seed crystal into contact with the Si—C solution.
  • the manufacturing method includes a preparation process and a growth process.
  • the preparation step the raw material is heated and melted to prepare a Si—C solution.
  • the growth step a crystal growth surface consisting of only one of the facet region and the non-facet region is brought into contact with the Si—C solution to grow a SiC single crystal on the crystal growth surface.
  • the SiC single crystal manufacturing method further includes a center position of the crystal growth surface of the SiC seed crystal having a radius R and a virtual circle having a radius of 1 / 3R centered on the center position, Positions arranged at every central angle of 45 ° are defined as a plurality of first measurement positions.
  • a plurality of second measurement positions are positions on a virtual circle having a radius of 2 / 3R centered on the center position and arranged at intervals of 45 ° of the center angle.
  • the ratio of the difference value between the maximum value and the minimum value with respect to the minimum value is 15% or less.
  • the SiC seed crystal according to the present embodiment is an SiC seed crystal used in the solution growth method.
  • the SiC seed crystal has a crystal growth surface composed of only one of a facet region and a non-facet region.
  • the SiC seed crystal according to the present embodiment further includes a center position of the crystal growth surface of the SiC seed crystal having the radius R and a virtual circle having a radius of 1 / 3R centered on the center position and a center angle of 45. Positions arranged at every ° are defined as a plurality of first measurement positions.
  • a plurality of second measurement positions are positions on a virtual circle having a radius of 2 / 3R centered on the center position and arranged at intervals of 45 ° of the center angle.
  • the ratio of the difference value between the maximum value and the minimum value with respect to the minimum value is 15% or less.
  • the SiC single crystal manufacturing method according to the present embodiment and the SiC seed crystal according to the present embodiment, the occurrence of solvent inclusion can be suppressed.
  • FIG. 1 shows the ratio of the difference between the maximum value and the minimum value with respect to the minimum value of nitrogen concentration (nitrogen concentration variation Nc) (%) and the crystal growth at a specific measurement position in the crystal growth surface of the SiC seed crystal. It is a figure which shows the relationship with the ratio (inclusion free degree) of the thickness which a crystal grows without generating solvent inclusion with respect to the total crystal growth thickness.
  • FIG. 2 is a schematic view of a manufacturing apparatus used in the method for manufacturing the SiC single crystal according to the present embodiment.
  • FIG. 3 is a bottom view (crystal growth surface diagram) of a conventional SiC seed crystal including both a facet region and a non-facet region on the crystal growth surface.
  • FIG. 4 is a bottom view of a conventional SiC seed crystal including both a facet region and a non-facet region on a crystal growth surface different from FIG.
  • FIG. 5 is a diagram showing the measurement position of the nitrogen concentration on the crystal growth surface.
  • the present inventors have made various studies on a method for producing an SiC single crystal by a solution method that can suppress the occurrence of solvent inclusion. As a result, the following knowledge was obtained.
  • the SiC single crystal is grown by bringing the crystal growth surface of the SiC seed crystal into contact with the Si-C solution.
  • the SiC seed crystal may include a facet region.
  • a facet region refers to a region having the same crystal structure as other regions and having a higher screw dislocation density and nitrogen concentration than other regions.
  • the screw dislocation has a small staircase at an atomic level called a step where crystal growth is likely to proceed.
  • the facet region is a source of steps during crystal growth because of the high screw dislocation density. That is, if a facet region is included in the crystal growth surface, crystal growth proceeds preferentially in the facet region compared to other regions.
  • An area that is not a facet area is hereinafter referred to as a non-facet area. That is, the non-faceted region refers to a region having a lower screw dislocation density and a nitrogen concentration than other regions.
  • the present inventors have newly found that solvent inclusion occurs due to the difference in crystal growth rate between the facet region and the non-facet region. That is, the solvent inclusion generated due to the difference in crystal velocity between the facet region and the non-facet region is a problem specific to the solution method.
  • step bunching promotes three-dimensional growth of SiC single crystal. If the SiC single crystal grows three-dimensionally, a part of the solvent is confined in the SiC single crystal, and solvent inclusion occurs.
  • a SiC seed crystal whose crystal growth surface is composed of only one of a facet region and a non-facet region is used.
  • the seed crystal region is inherited in the whole process of crystal growth. Therefore, the crystal growth surface of the SiC single crystal of the present embodiment consists of only one of the facet region and the non-facet region. Thereby, the difference in the crystal growth rate is reduced over the entire crystal growth surface. That is, variations in the crystal growth thickness are suppressed. This suppresses step bunching and three-dimensional growth of the SiC single crystal. As a result, solvent inclusion can be suppressed.
  • the nitrogen concentration in faceted areas is high. Therefore, if the variation in the nitrogen concentration on the crystal growth surface is small, it means that the crystal growth surface consists of only one of the facet region and the non-facet region. That is, if the variation in nitrogen concentration on the crystal growth surface is small, solvent inclusion can be suppressed as described above.
  • the variation in nitrogen concentration refers to the center position of the crystal growth surface of the SiC seed crystal having the radius R and the imaginary circle having a radius of 1 / 3R centered on the center position, and arranged at every center angle of 45 °.
  • the nitrogen concentration at a plurality of first measurement positions and a plurality of second measurement positions on a virtual circle with a radius of 2 / 3R centered on the center position and arranged at a central angle of 45 ° It means the ratio of the difference between the maximum value and the minimum value with respect to the minimum value.
  • FIG. 1 shows the ratio of the difference between the maximum value and the minimum value with respect to the minimum value of nitrogen concentration (nitrogen concentration variation Nc) (%) and the crystal growth at a specific measurement position in the crystal growth surface of the SiC seed crystal. It is a figure which shows the relationship with the ratio (inclusion free degree) of the thickness which a crystal grows without generating solvent inclusion with respect to the total crystal growth thickness.
  • FIG. 1 is a graph plotting the results of Examples described later.
  • the inclusion freeness is 1.0 and is almost constant. That is, crystal growth can be achieved without causing significant solvent inclusion at the total crystal growth thickness.
  • the SiC single crystal manufacturing method according to the present embodiment completed based on the above knowledge is a manufacturing method by a solution growth method.
  • the SiC single crystal is grown by bringing the crystal growth surface of the SiC seed crystal into contact with the Si—C solution.
  • the manufacturing method includes a preparation process and a growth process.
  • the preparation step the raw material is heated and melted to prepare a Si—C solution.
  • the growth step a crystal growth surface consisting of only one of the facet region and the non-facet region is brought into contact with the Si—C solution to grow a SiC single crystal on the crystal growth surface.
  • the SiC single crystal manufacturing method further includes a center position of the crystal growth surface of the SiC seed crystal having a radius R and a virtual circle having a radius of 1 / 3R centered on the center position, Positions arranged at every central angle of 45 ° are defined as a plurality of first measurement positions.
  • a plurality of second measurement positions are positions on a virtual circle having a radius of 2 / 3R centered on the center position and arranged at intervals of 45 ° of the center angle.
  • the ratio of the difference value between the maximum value and the minimum value with respect to the minimum value is 15% or less.
  • the crystal growth surface of the SiC single crystal is composed of only one of the facet region and the non-facet region, and the solvent inclusion can be suppressed.
  • the longest diameter passing through the center position of the crystal growth surface of the SiC single crystal is 2 inches or more. That is, the size of the crystal growth surface of the SiC single crystal is 2 inches or more.
  • a SiC single crystal may be grown 2 mm or more on the crystal growth surface.
  • the yield of the SiC single crystal can be increased.
  • the SiC seed crystal and the SiC single crystal may have a 4H polymorphic crystal structure.
  • the SiC seed crystal of this embodiment is used in the above-described solution method, and has a crystal growth surface composed of only one of a facet region and a non-facet region. Therefore, solvent inclusion can be suppressed.
  • the center of the crystal growth surface of the SiC seed crystal having the radius R is the center position on the crystal growth surface of the SiC seed crystal.
  • a plurality of first measurement positions are positions on a virtual circle having a radius of 1 / 3R centered on the center position and arranged at every central angle of 45 °.
  • a plurality of second measurement positions are positions on a virtual circle having a radius of 2 / 3R centered on the center position and arranged at intervals of 45 ° of the center angle.
  • the ratio of the difference value between the maximum value and the minimum value with respect to the minimum value is 15% or less.
  • the crystal growth surface of the SiC seed crystal consists of only one of the facet region and the non-facet region, and the solvent inclusion can be suppressed.
  • Crystal growth plane consisting of only one of facet region and non-facet region The crystal growth surface consisting of only one of the facet region and the non-facet region means a crystal growth surface having a nitrogen concentration variation Nc defined as follows of 15% or less.
  • the center of the crystal growth surface of the SiC seed crystal having the radius R is set as the center position.
  • a plurality of first measurement positions are positions on a virtual circle having a radius of 1 / 3R centered on the center position and arranged at every central angle of 45 °.
  • a plurality of second measurement positions are positions on a virtual circle having a radius of 2 / 3R centered on the center position and arranged at intervals of 45 ° of the center angle.
  • the minimum value is Nmin
  • the maximum value is Nmax
  • the difference value between the maximum value Nmax and the minimum value Nmin is ⁇ N.
  • ⁇ N Nmax ⁇ Nmin.
  • the facet region has the same crystal structure as other regions, and has higher screw dislocation density and nitrogen concentration than other regions.
  • the screw dislocation has a small staircase at an atomic level called a step where crystal growth is likely to proceed.
  • the facet region is a source of steps during crystal growth because of the high screw dislocation density. That is, if a facet region is included in the crystal growth surface, crystal growth proceeds preferentially in the facet region compared to other regions.
  • An area that is not a facet area is hereinafter referred to as a non-facet area. That is, the non-faceted region refers to a region having a lower screw dislocation density and a nitrogen concentration than other regions.
  • the facet region can be confirmed by measuring the screw dislocation density or nitrogen concentration by a known method.
  • the facet area can also be confirmed by the following method.
  • the SiC seed crystal is cut to a thickness of 1 mm or less.
  • the cut piece is placed in front of a light source such as an incandescent bulb to transmit light.
  • a light source such as an incandescent bulb to transmit light.
  • the crystal growth surface of the SiC single crystal and the SiC seed crystal of the present embodiment if the nitrogen concentration variation Nc is 15% or less, the crystal growth surface consists of only one of the facet region and the non-facet region. This Nc measurement method will be described later.
  • the manufacturing method of the SiC single crystal according to the present embodiment includes a preparation process and a growth process.
  • FIG. 2 is a schematic diagram of an example of a manufacturing apparatus 1 used in the method for manufacturing a SiC single crystal according to the present embodiment.
  • the manufacturing apparatus 1 includes a chamber 2, a crucible 5, a heat insulating member 4, an induction heating device 3, a rotating device 20, and a seed shaft 6.
  • Chamber 2 is a casing.
  • the chamber 2 accommodates the heat insulating member 4 and the induction heating device 3.
  • the chamber 2 can further accommodate a crucible 5.
  • the chamber 2 is cooled with a cooling medium.
  • the crucible 5 is housed in a casing-shaped heat insulating member 4.
  • the crucible 5 is a housing whose upper end is open.
  • the crucible 5 may be provided with a top plate. In this case, evaporation of the Si—C solution 7 can be suppressed.
  • the crucible 5 accommodates the Si—C solution 7.
  • the Si-C solution 7 is produced by melting the raw material by heating.
  • the raw material may be only Si, or may contain Si and another metal element.
  • the metal element contained in the raw material of the Si-C solution 7 is selected from the group consisting of titanium (Ti), manganese (Mn), chromium (Cr), cobalt (Co), vanadium (V), and iron (Fe). 1 type, or 2 or more types.
  • the Si—C solution 7 is generated by further dissolving carbon (C) in these raw materials. When carbon (C) is supplied from the added carbon source to the Si—C solution 7, the raw material of the Si—C solution 7 contains carbon (C).
  • the crucible 5 When supplying carbon (C) to the Si—C solution 7 by melting the crucible 5, the crucible 5 preferably contains carbon (C). More preferably, the material of the crucible 5 is graphite. When supplying carbon (C) from the added carbon source to the Si—C solution 7, the crucible 5 may be any material that is stable at the crystal growth temperature. In this case, the material of the crucible 5 may be ceramics or a high melting point metal. When the crucible 5 is made of a material other than graphite, a film containing graphite may be formed on the inner surface of the crucible 5.
  • the heat insulating member 4 surrounds the crucible 5.
  • the heat insulating member 4 is made of a well-known heat insulating material.
  • the heat insulating material is, for example, a fiber-based or non-fiber-based molded heat insulating material.
  • the induction heating device 3 surrounds the heat insulating member 4.
  • the induction heating device 3 includes a high frequency coil.
  • the high frequency coil is disposed coaxially with the seed shaft 6.
  • the induction heating device 3 induction-heats the crucible 5 by electromagnetic induction and melts the raw material stored in the crucible 5 to generate the Si—C solution 7.
  • the induction heating device 3 further maintains the Si—C solution 7 at the crystal growth temperature.
  • Rotating device 20 is a shaft extending in the height direction of chamber 2.
  • the upper end of the rotating device 20 is disposed inside the chamber 2.
  • the crucible 5 is disposed on the upper surface of the rotating device 20.
  • the rotation device 20 is connected to a drive source 21 and rotates around the central axis of the rotation device 20 by the drive source 21. When the rotating device 20 rotates, the crucible 5 rotates.
  • the crucible 5 and the rotating device 20 may rotate or may not rotate.
  • the seed shaft 6 is a shaft extending in the height direction of the chamber 2.
  • the upper end of the seed shaft 6 is disposed outside the chamber 2.
  • the seed shaft 6 is attached to the drive source 9 outside the chamber 2.
  • the lower end of the seed shaft 6 is disposed inside the crucible 5.
  • An SiC seed crystal 8 is attached to the lower end of the seed shaft 6.
  • the seed shaft 6 can be moved up and down and rotated by a drive source 9.
  • the seed shaft 6 is lowered by the drive source 9, and the SiC seed crystal 8 comes into contact with the Si—C solution 7.
  • the seed shaft 6 is rotated by the drive source 9, and the SiC seed crystal 8 is rotated.
  • the rotation direction of the seed shaft 6 may be the same as the rotation direction of the crucible 5 or may be the opposite direction.
  • the seed shaft 6 may rotate or may not rotate.
  • the seed shaft 6 is graphite.
  • SiC seed crystal An SiC seed crystal 8 having a crystal growth surface composed of only one of a facet region and a non-facet region is prepared.
  • the SiC seed crystal 8 has a plate shape and is made of a SiC single crystal.
  • the crystal structure of SiC seed crystal 8 is the same as the crystal structure of the SiC single crystal to be manufactured.
  • FIG. 3 is a bottom view (crystal growth surface diagram) of a conventional SiC seed crystal including both a facet region and a non-facet region on the crystal growth surface.
  • the crystal growth surface 80 of the conventional SiC seed crystal 8 includes a boundary 82 between a facet region 81 and a non-facet region. That is, the crystal growth surface 80 of the conventional SiC seed crystal 8 includes both the non-facet region and the facet region 81. Of the crystal growth surface 80 of the SiC seed crystal 8, a region other than the facet region 81 is a non-facet region. In the present embodiment, the crystal growth surface 80 of the SiC seed crystal 8 does not include the boundary 82 between the facet region and the non-facet region. That is, the crystal growth surface 80 of the SiC seed crystal 8 includes only one of the non-facet region and the facet region 81.
  • the crystal growth surface 80 may be a circle having a radius R shown in FIG.
  • the shape of the crystal growth surface 80 is, for example, a hexagon shown in FIG.
  • the shape of the crystal growth surface 80 may be another polygon (such as a quadrangle and an octagon), or may be an ellipse.
  • R is the length of the longest line segment connecting the center position C1 of the crystal growth surface 80 of the SiC seed crystal 8 and the outer periphery 84 of the crystal growth surface 80. If the longest diameter passing through the center position C1 of the crystal growth surface 80 is 2 inches or more, a large SiC single crystal can be obtained.
  • the shape of the crystal growth surface 80 is not particularly limited.
  • the adjustment of the seed crystal in which the crystal growth surface 80 includes only one of the non-facet region and the facet region 81 can also be realized by taking out the seed crystal from the facet region 81.
  • the seed crystal in which the crystal growth surface 80 includes only one of the non-facet region and the facet region 81 is manufactured by being cut out from the SiC single crystal ingot so as not to include the facet region 81.
  • the entire seed crystal consists of a non-faceted region.
  • Another embodiment of the method for adjusting the seed crystal in which the crystal growth surface 80 includes only one of the facet region and the non-facet region can be achieved by cutting the entire seed crystal from the facet region 81.
  • a known method can be adopted as a method for cutting out the SiC single crystal ingot. For example, a blade saw method and a wire saw method. When the SiC seed crystal 8 is cut out, it is adjusted as appropriate as described above.
  • the density variation Nc is 15% or less.
  • the measurement position C1 is the center position of the crystal growth surface 80.
  • the measurement positions C2 to C9 are first measurement positions that are arranged on a virtual circle having a radius of 1 / 3R with the center position C1 as the center at every central angle of 45 °. It is.
  • Measurement positions C10 to C17 are second measurement positions that are arranged at 45 ° central angles on a virtual circle having a radius of 2 / 3R with the center position C1 as the center.
  • the nitrogen concentration variation Nc at each measurement position C1 to C17 is sufficiently small as 15% or less.
  • the variation Nc in the nitrogen concentration at each measurement position is sufficiently small, and the crystal growth surface 80 of the SiC seed crystal 8 consists of only one of the non-facet region and the facet region 81. As a result, solvent inclusion can be suppressed.
  • the crystal growth surface 80 of the SiC seed crystal 8 includes a boundary 82 between the facet region 81 and the non-facet region. That is, the crystal growth surface 80 of the SiC seed crystal 8 includes both the non-facet region and the facet region 81. In this case, solvent inclusion occurs.
  • Nitrogen concentration variation Nc is preferably 12% or less. In this case, solvent inclusion can be further suppressed.
  • the nitrogen concentration at each measurement position C1 to C17 is obtained by the following method.
  • a sample is taken from a circular region having a diameter (5/100) R to (10/100) R with the respective measurement positions C1 to C17 on the crystal growth surface 80 of the SiC seed crystal 8 as the center.
  • a composition analysis is performed on the collected sample to obtain a nitrogen content.
  • the composition analysis is performed using, for example, a secondary ion mass spectrometer (SIMS).
  • SIMS secondary ion mass spectrometer
  • the nitrogen concentration (atoms / cm 3 ) at each measurement position C1 to C17 is obtained. From the obtained nitrogen concentration, the ratio of the difference value between the maximum value and the minimum value with respect to the minimum value, that is, the nitrogen concentration variation Nc (%) is calculated.
  • Si-C solution The raw material is heated and melted to produce the Si—C solution 7.
  • the raw material of the Si—C solution 7 having the above composition is stored in the crucible 5.
  • the crucible 5 containing the raw material is disposed on the upper surface of the rotating device 20 in the chamber 2.
  • the chamber 2 is filled with an inert gas, for example, helium gas.
  • the raw material of the crucible 5 and the Si—C solution 7 is heated by the induction heating device 3 to the melting point or higher of the raw material of the Si—C solution 7. If the crucible 5 containing carbon is heated, carbon melts from the crucible 5 into the melt. As a result, a Si—C solution 7 is generated.
  • the Si—C solution 7 As another method, there is a method via a gas phase in which carbon is dissolved from a hydrocarbon gas into the Si—C solution 7. As yet another method, there is a method in which a solid-phase carbon source is charged into the Si—C solution 7 and dissolved.
  • the solid-phase carbon source is, for example, one or more selected from the group consisting of graphite, amorphous carbon raw material, SiC, and carbides of additive elements. These are added to the Si-C solution 7 in the form of blocks, rods, granules and powders.
  • the Si—C solution 7 is generated by heating the raw material containing carbon.
  • the heating is performed until the Si-C solution 7 reaches the crystal growth temperature. Heating may be continued up to the crystal growth temperature, or a period for holding at a constant temperature may be provided. When holding at a constant temperature, the holding temperature should just be more than the liquidus temperature of a raw material. In this case, heating is performed until the carbon in the Si—C solution 7 approaches a supersaturated state. When using a solid carbon source, it is preferable to heat until the carbon source is completely dissolved.
  • the heating time is, for example, 0.5 to 10 hours.
  • the crystal growth surface 80 of the SiC seed crystal 8 is brought into contact with the Si—C solution 7 to grow a SiC single crystal on the crystal growth surface 80 of the SiC seed crystal 8.
  • the crystal growth surface 80 of the SiC seed crystal 8 is brought into contact with the Si—C solution 7 (hereinafter also referred to as a landing liquid).
  • the crystal growth surface 80 includes only one of the non-facet region and the facet region 81.
  • a seed crystal composed of only one of the non-facet region and the facet region 81 can be realized by using a crystal from which the facet region 81 is completely removed as a seed crystal. Alternatively, it can be realized by taking out the seed crystal from the facet region 81.
  • the output of the induction heating device 3 is adjusted to maintain the temperature of the Si—C solution 7 at the crystal growth temperature.
  • the crystal growth temperature is, for example, 1850 to 2100 ° C.
  • a SiC single crystal By applying a temperature gradient to the Si-C solution 7, a SiC single crystal can be produced efficiently. Specifically, a temperature gradient is applied so that the vicinity of the SiC seed crystal 8 in the Si—C solution 7 is lower in temperature than other portions. Thereby, the supersaturation degree of SiC in the vicinity of SiC seed crystal 8 can be increased. As a result, the growth rate of the SiC single crystal is increased.
  • the output of the induction heating device 3 is adjusted to give a temperature gradient so that the upper part of the Si—C solution 7 becomes a low temperature. Otherwise, the output of the induction heating device 3 is adjusted so that the temperature of the Si—C solution 7 is maintained by heat transfer from the crucible 5.
  • a temperature gradient is applied so that the center of the Si—C solution 7 has a low temperature.
  • the temperature gradient is preferably in the range of 5 to 50 ° C./cm regardless of the vertical direction or the horizontal direction. If the temperature gradient is 5 ° C./cm or more, the growth rate of the SiC single crystal is increased. If the temperature gradient is 50 ° C./cm or less, spontaneous generation of SiC nuclei in the Si—C solution 7 can be suppressed.
  • the growth step may be performed while maintaining the temperature of the Si—C solution 7 constant or may be performed while the temperature is increased.
  • the degree of supersaturation of the carbon concentration in the Si—C solution 7 can be adjusted to an appropriate range. Therefore, spiral growth proceeds predominantly. As a result, mixing of different crystal polymorphs due to two-dimensional nucleus growth can be further suppressed.
  • the growth step is performed while raising the temperature of the Si—C solution 7, if the rate of temperature rise is within a certain range, the two-dimensional nucleus growth can be stably suppressed without dissolving the SiC single crystal.
  • a meniscus may be formed after the landing.
  • the SiC seed crystal 8 in contact with the Si—C solution 7 is pulled upward from the liquid level of the Si—C solution 7.
  • the meniscus height is, for example, 0.1 to 4.0 mm.
  • FIG. 2 the example of the manufacturing apparatus 1 using the crucible 5 is shown.
  • a levitation method in which the raw material is levitated and melted by electromagnetic force without using the crucible 5 may be employed.
  • a cold crucible method for generating the Si—C solution 7 levitated by magnetic repulsion in a water-cooled metal crucible may be employed.
  • the SiC single crystal of this embodiment can be manufactured through the above steps.
  • Test number 1 The manufacturing apparatus 1 shown in FIG. 2 was used.
  • the crucible 5 was a graphite crucible
  • the induction heating device 3 was a high-frequency coil
  • the seed shaft 6 was graphite
  • the chamber 2 was a water-cooled stainless steel chamber.
  • the inside of the production apparatus was replaced with helium gas.
  • the raw material of the graphite crucible and the Si—C solution was heated by a high frequency coil to prepare an Si—C solution.
  • a temperature gradient was formed so that the upper part of the Si-C solution had a low temperature.
  • the temperature gradient was formed by controlling the positional relationship between the graphite crucible and the high frequency coil. Specifically, the temperature gradient was formed by arranging the Si—C solution so that the center portion is located above the center of the high-frequency coil (heat generation center). The temperature gradient was confirmed by inserting a thermocouple into the Si—C solution in advance and measuring the temperature separately from this example. The temperature gradient in the vicinity of the SiC seed crystal was about 12 ° C./cm. The temperature of the Si-C solution near the SiC seed crystal during crystal growth was measured. The measurement was performed by measuring the temperature of the graphite on the back surface of the SiC seed crystal with an optical thermometer using a seed shaft provided with a temperature measuring hole. The crystal growth temperature was 1940 ° C.
  • the seed shaft was lowered to allow the SiC seed crystal to land on the Si-C solution.
  • the SiC seed crystal was manufactured by a sublimation recrystallization method and had a circular crystal growth surface with a diameter of 50.8 mm.
  • the crystal structure and crystal growth surface of the SiC seed crystal were 4H—SiC (000-1) on axis.
  • test number 1 the facet region was visually confirmed when the seed crystal was produced, and the facet region was completely removed.
  • the nitrogen concentration and the nitrogen concentration variation Nc on the growth surface of the SiC seed crystal were measured by the method described above.
  • the seed shaft After landing, the seed shaft was pulled up to form a meniscus. The meniscus height was 0.5 mm. Crystal growth was performed while keeping the temperature of the Si-C solution constant. The crucible and the seed shaft were rotated at 10 rpm in the opposite direction. The time from the landing to the end of crystal growth was 50 hours. After completion of crystal growth, the seed shaft was raised to separate the SiC single crystal from the Si—C solution. After slowly cooling the graphite crucible to room temperature, the SiC single crystal was separated from the seed shaft and collected.
  • Test number 2 The SiC seed crystal used in Test No. 2 was produced by a sublimation recrystallization method and had a circular crystal growth surface with a diameter of 33.0 mm. The crystal structure and crystal growth surface of the SiC seed crystal were 4H-SiC (000-1) on axis. Test number 2 was the same as test number 1 except that the facet region was visually confirmed at the time of preparation of the seed crystal and the crystal was cut out from the facet region so that the entire crystal growth surface was a SiC seed crystal. Crystal growth was performed.
  • Test number 3 The SiC seed crystal used in Test No. 3 was produced by a sublimation recrystallization method and had a circular crystal growth surface with a diameter of 50.8 mm. The crystal structure and crystal growth surface of the SiC seed crystal were 4H-SiC (000-1) on axis. In Test No. 3, crystal growth was performed in the same manner as in Test No. 1 except that the temperature gradient in the vicinity of the SiC seed crystal was about 15 ° C./cm and the growth time was 15 hours.
  • Test number 4 The SiC seed crystal used in Test No. 4 was produced by a sublimation recrystallization method and had a circular crystal growth surface with a diameter of 50.8 mm.
  • the crystal structure and crystal growth surface of the SiC seed crystal were 4H-SiC (000-1) on axis.
  • test number 4 the facet region was visually confirmed at the time of preparation of the seed crystal, and the test number was 1 except that the crystal was cut out so that the crystal growth surface was a SiC seed crystal including both the facet region and the non-facet region. Crystal growth was performed in the same manner as described above.
  • Test No. 5 The SiC seed crystal used in test number 5 was manufactured by a sublimation recrystallization method and had a circular crystal growth surface with a diameter of 33.0 mm.
  • the crystal structure and crystal growth surface of the SiC seed crystal were 4H-SiC (000-1) on axis.
  • Test No. 5 except that the non-faceted region was visually confirmed at the time of preparation of the seed crystal, and the crystal was cut out so that the crystal growth surface was an SiC seed crystal including the non-faceted region and the facet region. Crystal growth was performed in the same manner as described above.
  • the inclusion free degree was measured in the SiC single crystal of each test number. Specifically, it measured as follows.
  • test number 4 and test number 5 the nitrogen concentration variation Nc exceeded 15%. That is, the crystal growth surfaces of the SiC seed crystals of Test No. 4 and Test No. 5 include both facet regions and non-facet regions. Therefore, the SiC single crystals of test number 4 and test number 5 had an inclusion freeness of 0.3.

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  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)

Abstract

La présente invention concerne un procédé de production d'un monocristal de SiC au moyen d'un procédé de croissance dans un solvant dans lequel il est possible de supprimer l'apparition d'inclusions de solvant, et un germe de SiC destiné à être utilisé dans un procédé de croissance dans un solvant. Le procédé de production d'un monocristal de SiC, conformément au présent mode de réalisation, est un procédé de production impliquant un procédé de croissance dans un solvant dans lequel le plan de croissance (80) du cristal d'un germe (8) de SiC (8) est mis en contact avec la solution (7) de Si-C et un monocristal de SiC est mis en croissance. Le procédé de production comporte une étape de préparation et une étape de mise en croissance. Lors de l'étape de préparation, une matière première est chauffée et fondue pour préparer la solution (7) de Si-C. Lors de l'étape de mise en croissance, le plan de croissance (80) du cristal est mis en contact avec la solution (7) de Si-C, et un monocristal de SiC est mis en croissance sur le plan de croissance (80) du cristal. Le plan de croissance (80) du cristal comprend uniquement une région parmi une région sans facette et une région à facettes (81). Le rapport de la différence de valeurs entre la valeur maximale et la valeur minimale par rapport à la valeur minimale de la concentration en azote à un emplacement de mesure spécifique dans le plan de croissance (80) du cristal du germe (8) de SiC est inférieur ou égal à 15 %.
PCT/JP2017/034852 2016-09-27 2017-09-27 PROCÉDÉ DE PRODUCTION D'UN MONOCRISTAL DE SiC, ET GERME DE SiC WO2018062224A1 (fr)

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JP2020047619A (ja) * 2018-09-14 2020-03-26 株式会社ディスコ ウエーハの生成方法およびレーザー加工装置

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CN114481318A (zh) * 2022-02-14 2022-05-13 北京青禾晶元半导体科技有限责任公司 一种碳化硅晶体生长的控制方法及装置

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JPH06227886A (ja) * 1993-02-05 1994-08-16 Toshiba Corp 半導体単結晶の製造方法
JP2012250897A (ja) * 2011-06-07 2012-12-20 Sumitomo Electric Ind Ltd 単結晶炭化珪素基板およびその製造方法
JP2015054814A (ja) * 2013-09-13 2015-03-23 トヨタ自動車株式会社 ＳｉＣ単結晶及びその製造方法
JP2016056079A (ja) * 2014-09-09 2016-04-21 トヨタ自動車株式会社 ＳｉＣ単結晶及びその製造方法

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JPH06227886A (ja) * 1993-02-05 1994-08-16 Toshiba Corp 半導体単結晶の製造方法
JP2012250897A (ja) * 2011-06-07 2012-12-20 Sumitomo Electric Ind Ltd 単結晶炭化珪素基板およびその製造方法
JP2015054814A (ja) * 2013-09-13 2015-03-23 トヨタ自動車株式会社 ＳｉＣ単結晶及びその製造方法
JP2016056079A (ja) * 2014-09-09 2016-04-21 トヨタ自動車株式会社 ＳｉＣ単結晶及びその製造方法

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2020047619A (ja) * 2018-09-14 2020-03-26 株式会社ディスコ ウエーハの生成方法およびレーザー加工装置
JP7128067B2 (ja) 2018-09-14 2022-08-30 株式会社ディスコ ウエーハの生成方法およびレーザー加工装置

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