WO2015137439A1 - SiC単結晶の製造方法 - Google Patents
SiC単結晶の製造方法 Download PDFInfo
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- 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
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- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/0635—Carbides
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- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
- C23C16/32—Carbides
- C23C16/325—Silicon carbide
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- 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
- C30B19/02—Liquid-phase epitaxial-layer growth using molten solvents, e.g. flux
- C30B19/04—Liquid-phase epitaxial-layer growth using molten solvents, e.g. flux the solvent being a component of the crystal composition
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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
- C30B19/06—Reaction chambers; Boats for supporting the melt; Substrate holders
- C30B19/062—Vertical dipping system
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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
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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
- C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
- C30B23/02—Epitaxial-layer growth
- C30B23/025—Epitaxial-layer growth characterised by the substrate
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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
- C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
- C30B25/02—Epitaxial-layer growth
- C30B25/18—Epitaxial-layer growth characterised by the substrate
- C30B25/20—Epitaxial-layer growth characterised by the substrate the substrate being of the same materials as the epitaxial layer
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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
- C30B9/00—Single-crystal growth from melt solutions using molten solvents
- C30B9/04—Single-crystal growth from melt solutions using molten solvents by cooling of the solution
- C30B9/08—Single-crystal growth from melt solutions using molten solvents by cooling of the solution using other solvents
- C30B9/12—Salt solvents, e.g. flux growth
Definitions
- the present invention relates to a method for producing a SiC single crystal, and more particularly to a method for producing a SiC single crystal by a solution growth method.
- SiC Silicon carbide
- SiC is a thermally and chemically stable compound semiconductor.
- SiC has a superior band gap, breakdown voltage, electron saturation rate and thermal conductivity compared to silicon (Si). Therefore, SiC attracts attention as a next-generation semiconductor material.
- SiC is known as a material exhibiting crystal polymorphism.
- Typical crystal structures of SiC are hexagonal 6H, 4H and cubic 3C.
- a SiC single crystal having a 4H crystal structure (hereinafter referred to as a 4H-SiC single crystal) has a larger band gap than SiC single crystals having other crystal structures. Therefore, 4H—SiC single crystal has attracted attention as a next-generation power device material.
- Sublimation recrystallization is the most widely used method for producing SiC single crystals.
- defects such as micropipes are likely to occur in the SiC single crystal manufactured by the sublimation recrystallization method. Defects adversely affect device characteristics. Therefore, it is required to suppress the occurrence of defects.
- the solution growth method is disclosed in, for example, Japanese Patent Application Laid-Open No. 2009-91222.
- dislocations that adversely affect device characteristics.
- Such dislocations include, for example, threading dislocations.
- threading dislocations include threading screw dislocation (TSD) and threading edge dislocation (TED).
- TSD threading screw dislocation
- TED threading edge dislocation
- the threading screw dislocation propagates in the c-axis direction ( ⁇ 0001> direction) of the SiC single crystal and has a Burgers vector in the c-axis direction.
- the threading edge dislocation propagates in the c-axis direction and has a Burgers vector in a direction perpendicular to the c-axis direction.
- Micropipes are threading screw dislocations with a large Burgers vector.
- the basal plane defect is a defect formed in the basal plane.
- Basal plane defects include flank stacking faults and basal plane dislocations. This method is disclosed in, for example, Journal of Japanese Society for Crystal Growth Vol.40, No.1 (2013) p.25-32 (Non-Patent Document 1).
- threading edge dislocations are converted to basal plane dislocations extending in the step flow direction. Further, it is described that the threading edge dislocations may be converted into basal plane dislocations and may not be converted into basal plane dislocations.
- the conversion rate differs between the conversion rate of threading screw dislocations into flank stacking faults and the conversion rate of threading edge dislocations to basal plane dislocations. That is, the conversion rate to the basal plane defect differs between the threading screw dislocation and the threading edge dislocation. Therefore, threading dislocations in a grown single crystal can be reduced by improving the conversion rate of threading edge dislocations to basal plane dislocations while maintaining the conversion rate of threading screw dislocations to flank stacking faults. .
- the purpose of the present invention is to improve the conversion rate of threading edge dislocations to basal plane dislocations while maintaining the conversion rate of threading screw dislocations to flank stacking faults when producing SiC single crystals by solution growth It is to let you.
- the SiC single crystal manufacturing method is a method of manufacturing an SiC single crystal by a solution growth method.
- This method includes the following steps (a) and (b).
- Step (a) is a generation step in which the raw material in the crucible is heated and melted to produce a SiC solution.
- Step (b) is a growth step in which a SiC single crystal is grown on the crystal growth surface by bringing the crystal growth surface of the SiC seed crystal into contact with the SiC solution.
- the crystal structure of the SiC seed crystal is 4H polymorph.
- the off-angle of the crystal growth surface is 1 ° or more and 4 ° or less.
- the temperature of the SiC solution when growing the SiC single crystal is 1650 ° C. or more and 1850 ° C. or less.
- the temperature gradient immediately below the SiC seed crystal in the SiC solution is greater than 0 ° C./cm and not greater than 19 ° C./cm.
- the SiC single crystal manufacturing method according to the embodiment of the present invention can improve the conversion rate of threading edge dislocations to basal plane dislocations while maintaining the conversion rate of threading screw dislocations to flank stacking faults. .
- the SiC single crystal manufacturing method is a method of manufacturing an SiC single crystal by a solution growth method.
- This method includes a preparation step, a generation step, and a growth step.
- a manufacturing apparatus is prepared.
- an SiC solution is generated.
- the SiC seed crystal is brought into contact with the SiC solution to grow a SiC single crystal.
- FIG. 1 is a schematic diagram of a manufacturing apparatus 10 used in a method for manufacturing a SiC single crystal according to an embodiment of the present invention.
- a manufacturing apparatus 10 shown in FIG. 1 is an example of a manufacturing apparatus used for a solution growth method.
- the manufacturing apparatus used for the solution growth method is not limited to the manufacturing apparatus 10 shown in FIG.
- the manufacturing apparatus 10 includes a chamber 12, a crucible 14, a heat insulating member 16, a heating device 18, a rotating device 20, and a lifting device 22.
- the chamber 12 accommodates the crucible 14. When manufacturing a SiC single crystal, the chamber 12 is cooled.
- the crucible 14 accommodates the raw material of the SiC solution 15.
- the SiC solution 15 refers to a solution in which carbon (C) is dissolved in a melt of Si or Si alloy.
- the crucible 14 contains carbon.
- the crucible 14 becomes a carbon supply source to the SiC solution 15.
- the heat insulating member 16 is made of a heat insulating material and surrounds the crucible 14.
- the heating device 18 is, for example, a high frequency coil.
- the heating device 18 surrounds the side wall of the heat insulating member 16.
- the heating device 18 induction-heats the crucible 14 to generate the SiC solution 15.
- the heating device 18 further maintains the SiC solution 15 at the crystal growth temperature.
- the crystal growth temperature is the temperature of the SiC solution 15 when the SiC single crystal is grown, and is the temperature of the region in contact with the crystal growth surface 24A of the SiC seed crystal 24.
- the crystal growth temperature is 1650 to 1850 ° C., preferably 1700 to 1800 ° C.
- the rotating device 20 includes a rotating shaft 20A and a drive source 20B.
- the rotary shaft 20A extends in the height direction of the chamber 12 (vertical direction in FIG. 1).
- the upper end of the rotating shaft 20 ⁇ / b> A is located in the heat insulating member 16.
- a crucible 14 is disposed at the upper end of the rotating shaft 20A.
- the lower end of the rotation shaft 20 ⁇ / b> A is located outside the chamber 12.
- the drive source 20B is disposed below the chamber 12.
- the drive source 20B is connected to the rotation shaft 20A.
- the drive source 20B rotates the rotary shaft 20A around the central axis of the rotary shaft 20A.
- the elevating device 22 includes a seed shaft 22A and a drive source 22B.
- the seed shaft 22 ⁇ / b> A extends in the height direction of the chamber 12.
- the upper end of the seed shaft 22 ⁇ / b> A is located outside the chamber 12.
- a SiC seed crystal 24 is attached to the lower end surface of the seed shaft 22A.
- the drive source 22B is disposed above the chamber 12.
- the drive source 22B is connected to the seed shaft 22A.
- the drive source 22B moves up and down the seed shaft 22A.
- the drive source 22B rotates the seed shaft 22A around the central axis of the seed shaft 22A.
- an SiC seed crystal 24 is further prepared.
- the SiC seed crystal 24 is made of a SiC single crystal.
- the crystal structure of the SiC seed crystal 24 is a 4H polymorph.
- the crystal growth surface 24A of the SiC seed crystal 24 may be the C plane or the Si plane.
- the off angle of the crystal growth surface 24A is 1 ° to 4 °.
- the off-angle of the crystal growth surface 24A is an angle formed by a straight line extending in a direction perpendicular to the crystal growth surface 24A and a straight line extending in the c-axis direction. That is, the SiC seed crystal 24 is a 4H—SiC single crystal having a slight inclination in the [11-20] direction.
- the SiC seed crystal 24 is attached to the lower end surface of the seed shaft 22A.
- the crucible 14 is placed on the rotating shaft 20 ⁇ / b> A in the chamber 12.
- the crucible 14 contains the raw material of the SiC solution 15.
- the raw material may be, for example, only Si, or a mixture of Si and another metal element.
- the metal element include titanium (Ti), manganese (Mn), chromium (Cr), cobalt (Co), vanadium (V), iron (Fe), and the like.
- Examples of the form of the raw material include a plurality of lumps and powders.
- the SiC solution 15 is generated.
- the chamber 12 is filled with an inert gas.
- the raw material of the SiC solution 15 in the crucible 14 is heated more than melting
- FIG. When the crucible 14 is made of graphite, when the crucible 14 is heated, carbon is dissolved from the crucible 14 into the melt, and an SiC solution 15 is generated.
- the carbon in the crucible 14 dissolves in the SiC solution 15, the carbon concentration in the SiC solution 15 approaches the saturation concentration.
- the raw material of the SiC solution 15 contains C.
- the SiC solution 15 is held at the crystal growth temperature by the heating device 18. Subsequently, the seed shaft 22A is lowered by the drive source 22B, and the crystal growth surface 24A of the SiC seed crystal 24 is brought into contact with the SiC solution 15. At this time, the SiC seed crystal 24 may be immersed in the SiC solution 15.
- the SiC solution 15 is held at the crystal growth temperature by the heating device 18. Furthermore, the vicinity of the SiC seed crystal 24 in the SiC solution 15 is supercooled to bring SiC into a supersaturated state. At this time, the temperature gradient immediately below the SiC seed crystal 24 in the SiC solution is greater than 0 ° C./cm and 19 ° C./cm or less. When the temperature gradient is 0 ° C./cm, crystal growth does not start. When the temperature gradient exceeds 19 ° C./cm, the degree of supersaturation increases, so that three-dimensional growth occurs on the terrace, and step flow growth, which is two-dimensional growth, is hindered.
- the conversion rate to basal plane dislocation decreases.
- the lower limit of the temperature gradient is preferably 5 ° C./cm, more preferably 7 ° C./cm.
- the upper limit of the temperature gradient is preferably 15 ° C./cm, more preferably 11 ° C./cm.
- the method of supercooling the vicinity of the SiC seed crystal 24 in the SiC solution 15 is not particularly limited.
- the heating device 18 is controlled so that the temperature in the vicinity of the SiC seed crystal 24 in the SiC solution 15 is lower than the temperature in other regions.
- the vicinity of the SiC seed crystal 24 in the SiC solution 15 may be cooled by a refrigerant.
- the refrigerant is circulated inside the seed shaft 22A.
- the refrigerant is, for example, an inert gas such as helium (He) or argon (Ar). If the coolant is circulated in the seed shaft 22A, the SiC seed crystal 24 is cooled. When the SiC seed crystal 24 is cooled, the vicinity of the SiC seed crystal 24 in the SiC solution 15 is also cooled.
- the SiC seed crystal 24 and the SiC solution 15 are rotated while SiC in the vicinity of the SiC seed crystal 24 in the SiC solution 15 is in a supersaturated state.
- the SiC seed crystal 24 rotates.
- the crucible 14 rotates by rotating the rotating shaft 20A.
- the rotation direction of the SiC seed crystal 24 may be opposite to the rotation direction of the crucible 14 or the same direction.
- the rotation speed may be constant or may vary.
- the seed shaft 22A gradually rises while rotating. At this time, a SiC single crystal grows on the crystal growth surface of the SiC seed crystal 24 in contact with the SiC solution 15. Note that the seed shaft 22A may rotate without being raised, or may not be raised or rotated.
- FIG. 2 is a conceptual diagram showing threading screw dislocations and threading edge dislocations existing in a SiC single crystal.
- FIG. 3 is a conceptual diagram showing conversion of threading screw dislocations and threading edge dislocations into defects on the basal plane.
- the SiC single crystal 26 grows on the crystal growth surface 24A of the SiC seed crystal 24 by the above method.
- the SiC single crystal 26 has threading screw dislocations TSD and threading edge dislocations TED.
- the threading screw dislocation TSD propagates in the c-axis direction ( ⁇ 0001> direction) of the SiC single crystal 24 and has a Burgers vector b in the c-axis direction.
- the threading edge dislocation TED propagates in the c-axis direction and has a Burgers vector b in a direction perpendicular to the c-axis direction.
- the threading screw dislocation TSD is converted into a flank stacking fault SF as shown in FIG.
- the reason for this is that, for example, in step flow growth, a SiC single crystal is grown macroscopically in the c-axis direction, but microscopically, a lateral growth in which a macro step progresses is considered. It is done.
- the threading edge dislocation TED is converted into the basal plane dislocation BPD as shown in FIG.
- the threading edge dislocation TED is converted into the basal plane dislocation BPD and a case where it is not converted into the basal plane dislocation BPD.
- the SiC seed crystal 24 is a 4H—SiC single crystal with a slight inclination in the [11-20] direction
- the crystal growth surface 24A is an Si surface.
- the SiC single crystal 26 is step-flow grown in the off-angle direction, that is, the [11-20] direction.
- Burgers vector of threading edge dislocation TED is 1/3 ⁇ 11-20>, specifically, 1/3 [11-20], 1/3 [-12-10], 1/3 [ ⁇ There are six types: 2110], 1/3 [-1-120], 1/3 [1-210], and 1/3 [2-1-10].
- threading edge dislocations TED having Burgers vectors (1/3 [11-20], 1/3 [-1-120]) parallel to the step flow direction are almost all basal plane dislocations. Converted to BPD.
- the Burgers vector is not parallel to the step flow direction (1/3 [-12-10], 1/3 [-2110], 1/3 [1-210], 1/3 [2- 1-10])
- the threading edge dislocation TED is not easily converted to the basal plane dislocation BPD.
- FIG. 4A is an optical micrograph of the crystal surface of the SiC single crystal 26.
- FIG. 4B is an explanatory diagram illustrating a relationship between a step flow direction and a step.
- FIG. 5 is an explanatory diagram showing the relationship between the Burgers vector of the threading edge dislocation and the steps.
- the SiC single crystal 26 is formed on the crystal growth surface 24A of the SiC seed crystal 24 by step flow growth. Therefore, SiC single crystal 26 has step ST as shown in FIGS. 4A and 4B.
- step ST refers to the step of the crystal observed on the crystal surface by using an optical microscope, as shown in FIG. 4A.
- the step ST is inclined with respect to a reference line L1 extending in a direction perpendicular to the step flow direction D1 when viewed from a direction perpendicular to the crystal growth surface 24A.
- the inclination angle ⁇ with respect to the reference line L1 in step ST can be set to an appropriate size.
- the conversion rate of the threading edge dislocation TED to the basal plane dislocation BPD is improved. For example, the following reasons are conceivable.
- the Burgers vector of the threading edge dislocation TED is 1/3 ⁇ 11-20>. Specifically, 1/3 [11-20], 1/3 [-12-10], 1/3 [-2110], 1/3 [-1-120], 1/3 [1-210] 1/3 [2-1-10]. These Burgers vectors exist every 60 ° around the c-axis. That is, the angle formed by two Burgers vectors adjacent around the c-axis is 60 °.
- FIG. 5 shows a 1/3 [11-20] Burgers vector and a 1/3 [-2110] Burgers vector.
- FIG. 5 shows [1-100] which bisects the angle formed by the 1/3 [11-20] Burgers vector and the 1/3 [-2110] Burgers vector.
- a step ST inclined with respect to the reference line L1 is formed as shown in FIG.
- step ST intersects with the [1-100] direction perpendicularly, that is, the angle ⁇ 1 at which step ST intersects with the [11-20] direction and the angle ⁇ 2 at which step ST intersects with the [ ⁇ 2110] direction. Shows the same case.
- the angle ⁇ 1 and the angle ⁇ 2 do not have to be the same size.
- the angle formed between ⁇ 11-20> and ⁇ 1-100> is 30 °.
- the inclination angle ⁇ should be larger than 15 ° and smaller than 90 °.
- step ST By forming the step ST, Burgers vectors (1/3 [-12-10], 1/3 [-2110], 1/3 [1-210], 1/3 [non-parallel to the step flow direction are formed. 2-1-10]) is converted into basal plane dislocation BPD. As a result, the conversion rate of the threading edge dislocation TED to the basal plane dislocation BPD can be improved as a whole.
- an SiC single crystal having few threading screw dislocations and threading edge dislocations can be produced. Therefore, when manufacturing a SiC single crystal by the sublimation recrystallization method or the high temperature CVD method using the SiC single crystal as a seed crystal, a high-quality SiC single crystal can be obtained at a high growth rate.
- a seed crystal composed of a SiC single crystal and a SiC crystal powder as a raw material for the SiC single crystal are placed in a crucible and heated in an inert gas atmosphere such as argon gas. At this time, the temperature gradient is set so that the seed crystal is slightly cooler than the raw material powder. After sublimation, the raw material is diffused and transported toward the seed crystal by a concentration gradient formed by a temperature gradient. The growth of the SiC single crystal is realized by recrystallizing the source gas that has arrived at the seed crystal on the seed crystal.
- a seed crystal composed of a SiC single crystal is arranged on a pedestal supported by a rod-shaped member in a vacuum vessel, and an SiC source gas is supplied from below the seed crystal to thereby form a surface of the seed crystal.
- a SiC single crystal is grown.
- SiC single crystals were manufactured under various manufacturing conditions. With respect to the manufactured SiC single crystal, the conversion rate of threading screw dislocations into flank stacking faults and the conversion rate of threading edge dislocations into basal plane dislocations were investigated.
- SiC single crystals were produced under the production conditions shown in Table 1.
- Examples 1 to 6 were within the scope of the present invention.
- the production conditions of Comparative Examples 1 to 8 were outside the scope of the present invention.
- the inclination angle ⁇ was measured by observing the surface of the SiC single crystal with an optical microscope.
- the step height was measured by observing the surface of the SiC single crystal with an atomic force microscope.
- the rate of conversion of threading screw dislocations into flank stacking faults (TSD conversion rate) and the rate of conversion of threading edge dislocations to basal plane dislocations (TED conversion rate) indicate etch thread dislocations and threading edge dislocations, respectively. It was determined by observing the pits. That is, for each of the threading screw dislocation and the threading edge dislocation, the number of etch pits formed on the surface of the SiC single crystal etched with molten KOH and the surface of the SiC seed crystal etched with molten KOH are formed.
- the difference from the number of etch pits was obtained, and the difference was obtained by dividing the difference by the number of etch pits formed on the surface of the SiC seed crystal etched with molten KOH.
- the etching time was 3 to 4 minutes.
- the temperature of the molten KOH was 500 ° C.
- the number of etch pits showing threading screw dislocations and threading edge dislocations was determined by observing the surface of the crystal etched with molten KOH with an optical microscope.
- Dislocation conversion was evaluated according to the following criteria.
- Table 2 “Excellent” indicates a case where the TSD conversion rate is 90% or more and the TED conversion rate is 50% or more.
- ⁇ good indicates a case where the TSD conversion rate is less than 90% and the TED conversion rate is 50% or more.
- X (not acceptable) indicates a case where none of the above is satisfied.
- Comparative Example 3 and Comparative Example 8 observation of etch pits was difficult due to dislocation growth, heterogeneous mixing, etc., and TSD conversion rate and TED conversion rate could not be measured.
- the surface structure was evaluated according to the following criteria.
- “Excellent” indicates a case where the inclination angle ⁇ is 30 ° or more and less than 90 °.
- ⁇ (good) indicates a case where the inclination angle ⁇ is 15 ° or more and less than 30 °.
- X (not acceptable) indicates a case where the inclination angle ⁇ is less than 15 °.
- ⁇ Comprehensive evaluation was evaluated according to the following criteria.
- ⁇ (Excellent) indicates that both are ⁇ in dislocation conversion and surface structure evaluation.
- ⁇ (good) indicates that none is x and one is ⁇ .
- X (not acceptable) indicates that either is x in dislocation conversion and surface structure evaluation.
- FIG. 6 is a graph showing the relationship between the crystal growth temperature and the conversion rate of threading screw dislocations into flank stacking faults for Examples 2 and 3 and Comparative Examples 7 and 8.
- FIG. 7 is a graph showing the relationship between the crystal growth temperature and the conversion rate of threading edge dislocations to basal plane dislocations in Examples 2 and 3 and Comparative Examples 7 and 8.
- FIG. 8 is a graph showing the relationship between the crystal growth temperature and the conversion rate of threading screw dislocations into flank stacking faults for Examples 1 and 6 and Comparative Examples 3 and 4.
- FIG. 9 is a graph showing the relationship between the crystal growth temperature and the conversion rate of threading edge dislocations to basal plane dislocations in Examples 1 and 6 and Comparative Examples 3 and 4.
- FIG. 10 is a graph showing the relationship between the temperature gradient and the conversion rate of threading edge dislocations to basal plane dislocations in Examples 1, 4, 7 and Comparative Example 5. As shown in FIG. 10, when the temperature gradient was larger than 0 ° C./cm and 19 ° C./cm or less, the conversion rate of threading edge dislocations to basal plane dislocations was improved.
Abstract
Description
準備工程では、溶液成長法に用いられる製造装置を準備する。図1は、本発明の実施の形態によるSiC単結晶の製造方法に用いられる製造装置10の模式図である。図1に示す製造装置10は、溶液成長法に用いられる製造装置の一例である。溶液成長法に用いられる製造装置は、図1に示す製造装置10に限定されない。
次に、SiC溶液15を生成する。先ず、チャンバ12内に不活性ガスを充填する。そして、加熱装置18により、坩堝14内のSiC溶液15の原料を融点以上に加熱する。坩堝14が黒鉛からなる場合、坩堝14を加熱すると、坩堝14から炭素が融液に溶け込み、SiC溶液15が生成される。坩堝14の炭素がSiC溶液15に溶け込むと、SiC溶液15内の炭素濃度は飽和濃度に近づく。坩堝14が炭素供給源として利用できない場合、SiC溶液15の原料はCを含有する。
次に、加熱装置18により、SiC溶液15を結晶成長温度に保持する。続いて、駆動源22Bにより、シードシャフト22Aを降下し、SiC種結晶24の結晶成長面24AをSiC溶液15に接触させる。このとき、SiC種結晶24をSiC溶液15に浸漬してもよい。
図2及び図3を参照しながら、上記方法によって製造されるSiC単結晶について説明する。図2は、SiC単結晶に存在する貫通螺旋転位及び貫通刃状転位を示す概念図である。図3は、貫通螺旋転位及び貫通刃状転位の基底面の欠陥への変換を示す概念図である。
Claims (5)
- 溶液成長法によるSiC単結晶の製造方法であって、
坩堝内の原料を加熱して溶融し、SiC溶液を生成する生成工程と、
SiC種結晶の結晶成長面を前記SiC溶液に接触させ、前記結晶成長面上に前記SiC単結晶を成長させる成長工程とを備え、
前記SiC種結晶の結晶構造は、4H多形であり、
前記結晶成長面のオフ角は、1°以上であって、且つ、4°以下であり、
前記成長工程では、
前記SiC単結晶を成長させるときの前記SiC溶液の温度は、1650℃以上であって、且つ、1850℃以下であり、かつ、
前記SiC単結晶を成長させるとき、前記SiC溶液のうち、前記SiC種結晶の直下の温度勾配は、0℃/cmよりも大きく、且つ、19℃/cm以下である、
SiC単結晶の製造方法。 - 請求項1に記載のSiC単結晶の製造方法であって、
前記SiC単結晶を成長させるときの前記SiC溶液の温度は、1700℃以上であって、且つ、1800℃以下である、SiC単結晶の製造方法。 - 請求項1又は2に記載のSiC単結晶の製造方法であって、
前記結晶成長面がC面である、SiC単結晶の製造方法。 - 昇華再結晶法又は高温CVD法によるSiC単結晶の製造方法であって、
SiC種結晶を準備する工程と、
前記SiC種結晶上に前記SiC単結晶を成長させる工程とを備え、
前記SiC種結晶は、請求項1~3の何れか1項に記載の方法によって製造される、SiC単結晶の製造方法。 - SiC種結晶の結晶成長面上において、[11-20]方向にステップフロー成長したSiC単結晶であって、
前記結晶成長面に垂直な方向から見て、ステップと、前記[11-20]方向と垂直な方向に延びる基準線との為す角度は、15°よりも大きく、且つ、90°よりも小さい角度であり、
前記結晶成長面と平行な方向から見て、バンチングしたステップの高さは、2nmよりも大きく、且つ、200nm以下であるSiC単結晶。
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CN106098890A (zh) * | 2016-06-21 | 2016-11-09 | 吉林大学 | 一种基于碳面SiC衬底的垂直结构氮极性GaN基绿光LED芯片及其制备方法 |
WO2018180013A1 (ja) * | 2017-03-28 | 2018-10-04 | 三菱電機株式会社 | 炭化珪素基板、炭化珪素基板の製造方法、および炭化珪素半導体装置の製造方法 |
WO2019043973A1 (ja) * | 2017-09-01 | 2019-03-07 | 住友電気工業株式会社 | 炭化珪素エピタキシャル基板 |
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JP6259740B2 (ja) * | 2014-09-11 | 2018-01-10 | 国立大学法人名古屋大学 | 炭化ケイ素の結晶の製造方法及び結晶製造装置 |
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JP2023039745A (ja) * | 2021-09-09 | 2023-03-22 | 信越化学工業株式会社 | SiC単結晶の製造方法、並びにSiC単結晶の転位を抑制する方法 |
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