WO2016088883A1 - 炭化珪素単結晶の製造方法及び炭化珪素単結晶基板 - Google Patents
炭化珪素単結晶の製造方法及び炭化珪素単結晶基板 Download PDFInfo
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- C—CHEMISTRY; METALLURGY
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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
- 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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- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B32/00—Carbon; Compounds thereof
- C01B32/90—Carbides
- C01B32/914—Carbides of single elements
- C01B32/956—Silicon carbide
- C01B32/963—Preparation from compounds containing silicon
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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
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- 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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- 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
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/24—Vacuum evaporation
- C23C14/243—Crucibles for source material
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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
- 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 silicon carbide single crystal in which a silicon carbide raw material is sublimated to grow a bulk silicon carbide single crystal on a seed crystal, and a silicon carbide single crystal substrate.
- Silicon carbide is a wide bandgap semiconductor with a wide forbidden bandwidth, and has characteristics that far surpass conventional silicon (Si) in terms of voltage resistance and heat resistance. Research and development is ongoing.
- SiC single crystal One technique for growing a silicon carbide single crystal (SiC single crystal) is a sublimation recrystallization method.
- this method also called the modified Rayleigh method, attaches a seed crystal made of SiC to the crucible lid, places the SiC raw material on the crucible container body, and sublimates the SiC raw material, so that the bulk form is formed on the seed crystal.
- the SiC single crystal is grown.
- impurity doping into the growing single crystal is also possible.
- nitrogen (N 2 ) gas can be added to the growing atmospheric gas.
- a SiC single crystal substrate is manufactured and used in the field of power electronics, etc. Then, it is used for the production of SiC devices.
- the crystal growth by the sublimation recrystallization method requires a temperature exceeding 2000 ° C., and the crystal growth is performed by providing a temperature gradient in the crucible in which the seed crystal and the SiC raw material are arranged.
- a crystal always includes crystal defects such as dislocation defects and stacking faults.
- dislocation defects include threading edge dislocations, basal plane dislocations, and screw dislocations.
- screw dislocations are 8 ⁇ 10 2 to 3 ⁇ 10 3 (pieces).
- Non-Patent Documents 2 and 3 In recent years, research and investigation on SiC crystal defects and device performance have progressed, and the effects of various defects are becoming apparent. In particular, it has been reported that screw dislocation causes a leakage current of the device and reduces the lifetime of the gate oxide film (see Non-Patent Documents 2 and 3), and a high-performance SiC device is manufactured. For this, at least a SiC single crystal substrate with reduced screw dislocations is required.
- Patent Document 1 a plane whose offset angle (off angle) is within 60 ° from the ⁇ 0001 ⁇ plane is used as the growth plane, and screw dislocations are generated in the growing SiC single crystal at a higher density than the surroundings.
- a bulk SiC single crystal is grown using a dislocation control seed crystal having a region capable of generating screw dislocations in a region of 50% or less of the growth plane, and the region capable of generating screw dislocations is c-axis during the growth.
- a method for producing a SiC single crystal is disclosed in which a silicon carbide single crystal is grown such that a region projected in the direction overlaps with a c-plane facet.
- Patent Document 1 discloses that an SiC single crystal having a region having a high screw dislocation density and a region having a screw dislocation density lower than this region can be produced by the manufacturing method.
- Patent Document 2 discloses that the thickness is at least 0 at a first growth atmosphere pressure of 3.9 kPa to 39.9 kPa and a first growth temperature of 2100 ° C. to less than 2300 ° C.
- a first growth step of growing a .5 mm silicon carbide single crystal, a second growth atmosphere pressure of 0.13 kPa to 2.6 kPa, and the temperature of the seed crystal is higher than the first growth temperature at 2400 ° C.
- Patent Document 2 discloses a method of obtaining a silicon carbide single crystal substrate that is cut from a bulk silicon carbide single crystal grown by the SiC single crystal manufacturing method and has less screw dislocations in the peripheral portion than in the central portion of the substrate. Disclosure.
- the screw dislocation in the SiC single crystal is converted into a stacking fault in the first growth step.
- a structural transformation is more likely to occur in the peripheral part than in the central part of the growth surface in the process of growing the SiC single crystal, and the screw dislocation density in the peripheral part is higher than in the central part of the substrate. It can be reduced to about 1/10. Therefore, it is extremely effective as a method for reducing screw dislocation.
- the region where the screw dislocation is reduced is a donut-shaped peripheral region excluding the central portion of the substrate, there is room for consideration in terms of further increasing the device yield.
- Patent Document 3 describes that the angle between 0.1 ° and 10 ° in the ⁇ 11-20> direction (or ⁇ 1-100> direction) with respect to the (0001) plane
- the manufacturing method of the SiC single crystal ingot which forms the (0001) facet surface in the edge part of a SiC single crystal ingot is made using the base substrate which has the off-angle of this as a seed crystal.
- Patent Document 3 since nitrogen is easily taken in a portion below the surface where the facet surface is formed, a region having a relatively low nitrogen concentration is formed on the center side of the SiC single crystal ingot, thereby causing variations in the nitrogen concentration. It discloses that a suppressed SiC single crystal substrate can be obtained.
- the obtained ingot is supposed to reduce dislocations in substantially the entire region, but the detailed mechanism for reducing dislocations is not clear, and the etch pit density (1 ⁇ 10 4 ⁇ 5 ⁇ 10 4 cm -2 ), the SiC single crystal substrate obtained can be reduced to 1/2 to 1/20, but how is the dislocation actually in the substrate? It is unknown whether it is distributed in
- Patent Document 4 discloses a silicon carbide single crystal at a first growth atmosphere pressure of 3.9 kPa to 39.9 kPa and a first growth temperature of 2100 ° C. to less than 2300 ° C. A first growth step to be grown, a second growth atmosphere pressure of 0.13 kPa to 2.6 kPa, and a second growth temperature at which the temperature of the seed crystal is higher than the first growth temperature and lower than 2400 ° C. And a second growth step of growing a silicon carbide single crystal thicker than the first growth step.
- Patent Document 4 discloses that a high-quality silicon carbide single crystal is obtained by structurally converting screw dislocations into stacking faults in the first growth step and increasing the temperature of the seed crystal in the second growth step. Discloses that high-speed growth with good productivity can be performed.
- Patent Document 5 discloses that a silicon carbide single crystal is used in a state where an impurity for controlling volume resistivity is added using a seed crystal whose crystal growth surface has an offset angle of 2 ° to 15 ° from the ⁇ 0001 ⁇ plane. A manufacturing method for crystal growth of crystals is disclosed. Patent Document 5 discloses that if a SiC single crystal substrate cut out from such a crystal is used, a high-performance semiconductor element with extremely low power loss can be manufactured with high yield.
- Patent Document 6 a plurality of suppression layers having different nitrogen concentrations and suppressing basal plane dislocation density are formed on the substrate, and then an active layer of a silicon carbide single crystal thin film is formed on the suppression layer.
- the manufacturing method of the epitaxial silicon carbide single crystal substrate characterized by this is disclosed.
- Patent Document 6 by changing the nitrogen concentration in a stepwise manner, an appropriate crystal distortion that does not cause new crystal dislocation is generated at the interface between the suppression layers or the interface between the suppression layer and the active layer. It is disclosed that strain can be concentrated on the interface, and as a result, it effectively acts on suppression of basal plane dislocations.
- Patent Document 7 has grown by sublimation growth of a SiC single crystal boule on a SiC single crystal seed while changing the temperature, changing the temperature gradient, and changing the composition and pressure of the atmospheric gas. Disclosed is a method in which the threading dislocation density of a SiC single crystal boule is converted from threading dislocations to basal plane dislocations during the growth of a SiC single crystal boule to substantially decrease from the first growing portion of the boule to the last growing portion of the boule. is doing.
- U.S. Patent No. 6,099,077 discloses minimizing the propagation of threading dislocations during growth from seeds to grown crystals.
- Patent Documents 1 to 7 it is possible to efficiently reduce screw dislocations and secure a wide range of reduced screw dislocations in spite of using spiral growth centering on screw dislocations.
- a method for producing a silicon carbide single crystal is not disclosed. Further, the nitrogen partial pressure in the growth atmosphere and the supply of the step from the facet have no influence on the reduction of the screw dislocation density, and neither of Patent Documents 1 to 7 discloses nor suggests.
- an object of the present invention is to obtain an SiC single crystal substrate that efficiently reduces the screw dislocations of the SiC single crystal obtained by the sublimation recrystallization method and secures a wide range of reduced screw dislocations.
- An object of the present invention is to provide a method for producing a SiC single crystal that can be used.
- Another object of the present invention is to provide a SiC single crystal substrate in which a region where screw dislocations are reduced is secured in a wide range.
- the present inventors can efficiently reduce the screw dislocation of the SiC single crystal obtained by the sublimation recrystallization method, and further consider the yield of the SiC device, etc.
- the means for obtaining the SiC single crystal substrate that can be secured by the above-mentioned method have been studied earnestly.
- the inventors of the present invention have grown a SiC single crystal so that a facet ⁇ 0001 ⁇ plane is formed at the peripheral edge of the crystal end face on which the bulk SiC single crystal is grown, and a main growth process for performing main crystal growth.
- a bulk SiC single crystal that solves the above problems can be obtained by including a growth sub-process in which crystal growth is performed under a predetermined pressure and temperature under a high nitrogen concentration. Completed the invention.
- the gist of the present invention is as follows. (1) A seed crystal made of silicon carbide is placed in a crucible lid body of a crucible having a crucible container body and a crucible lid body, a silicon carbide raw material is placed in the crucible container body, and the silicon carbide raw material is sublimated to seed.
- a silicon carbide single crystal characterized by including a growth sub-process in which crystal growth is performed at a higher nitrogen concentration, a growth atmosphere pressure of 3.9 kPa to 39.9 kPa, and a seed crystal temperature of 2100 ° C. to less than 2300 ° C.
- the main growth step is that the nitrogen concentration in the crystal is 1 ⁇ 10 18 cm ⁇ 3 or more and 1 ⁇ 10 20 cm ⁇ 3 or less, the growth atmosphere pressure is 0.13 kPa or more and 2.6 kPa or less, and the temperature of the seed crystal is The method for producing a silicon carbide single crystal according to any one of (1) to (3), wherein the temperature is higher than that of the growth substep and less than 2400 ° C. (5) The bulk shape so that the growth surface in the process of growing the bulk silicon carbide single crystal has a curved surface at the growth peripheral portion and is flat compared to the growth peripheral portion at the growth central portion.
- a method for producing a silicon carbide single crystal is forming the silicon carbide single crystal of claim 1 on the main surface of the seed crystal.
- a silicon carbide single crystal substrate having an off angle from the ⁇ 0001 ⁇ plane to the off orientation, and having a facet ⁇ 0001 ⁇ plane at the substrate peripheral portion of the substrate surface on the end point side of the vector indicating the off orientation, In the distribution of the screw dislocation density along the substrate diameter from the facet ⁇ 0001 ⁇ plane toward the starting point of the vector indicating the off orientation, there exists a distribution boundary of the screw dislocation density where the decrease rate of the screw dislocation density increases rapidly.
- a silicon carbide single crystal substrate characterized by the above.
- a complex helix is transmitted from a basal plane dislocation propagating in the basal plane with a Burgers vector of 1/3 ⁇ 11-20> (0001). It is known that dislocations are generated (D. Nakamura et al. Journal of Crystal Growth 304 (2007) 57-3), and in the present invention, these complex screw dislocations are referred to as helical dislocations.
- the method for producing a SiC single crystal of the present invention it is possible to efficiently reduce the screw dislocations of the SiC single crystal, and to obtain a SiC single crystal substrate in which a region where the screw dislocations are reduced is secured in a wide range. Can do.
- the SiC single crystal substrate of the present invention since a region where screw dislocations are reduced is secured in a wide range, a high-quality SiC device can be obtained with a high yield.
- FIG. 1 It is a schematic block diagram of the single crystal growth apparatus used in order to manufacture the SiC single crystal of this invention. It is a schematic longitudinal cross-sectional view which shows the process in which a facet ⁇ 0001 ⁇ plane is formed in the crystal peripheral part in the crystal
- (A) is a longitudinal section schematically showing a structure in which a heat removal hole having a sufficiently small diameter ⁇ compared to the diameter ⁇ of the SiC seed crystal is provided in the heat insulating material covering the lid of the crucible to which the SiC seed crystal is attached.
- (b) is a longitudinal cross-sectional view which shows typically the positional relationship of the heat removal hole of the heat insulating material of the single crystal growth apparatus shown by (a) figure, the surface shape of a SiC single crystal, and a facet.
- (A) is the longitudinal block diagram which shows typically the structure where the diameter of the heat removal hole of the heat insulating material which covers the cover body of the crucible which attaches a SiC seed crystal was expanded
- (b) is a figure (a). It is a longitudinal cross-sectional view which shows typically the heat removal hole of the heat insulating material of the shown single crystal growth apparatus, the surface shape of a SiC single crystal, and the positional relationship of a facet.
- 3 is a schematic plan view showing dislocation distribution measurement points and a screw dislocation density distribution boundary in the SiC single crystal substrate according to Example 1; 3 is a schematic cross-sectional view schematically showing the state of dislocation defects and stacking faults in the (1-100) longitudinal section of the SiC single crystal according to Example 1.
- a seed crystal (SiC seed crystal) made of silicon carbide is disposed in a crucible lid body of a crucible having a crucible container body and a crucible lid body, and an SiC raw material is disposed in the crucible container body.
- a SiC single crystal is grown by sublimating a SiC raw material to grow a bulk SiC single crystal on a SiC seed crystal.
- the ⁇ 0001 ⁇ plane and the main surface form a predetermined off angle such that the normal line of the ⁇ 0001 ⁇ plane is directed to a predetermined off orientation on the main surface (or surface). It has been cut out.
- the manufacturing method of the present invention is characterized in that the facet ⁇ 0001 ⁇ plane is formed at the crystal peripheral portion of the crystal end face on which the bulk SiC single crystal has grown, and the growth main process is performed prior to the main growth process for performing the main crystal growth.
- a growth sub-process adopting a growth condition different from the process is included.
- the facet ⁇ 0001 ⁇ plane is a smooth surface generated only in a region having an angle perpendicular to the ⁇ 0001> direction that is the c-axis of the crystal when a SiC single crystal is grown. Therefore, a SiC seed crystal sliced so that the normal of the ⁇ 0001 ⁇ plane has a predetermined off orientation and forms a predetermined off angle with respect to the main surface is used to facet the crystal peripheral portion of the crystal end face.
- the growth surface in the process of growing the bulk SiC single crystal 12 has a curved surface at the growth peripheral portion.
- the center portion may be crystal grown while being flatter than the growth peripheral portion.
- the obtained SiC single crystal 12 has a flat crystal central portion of the crystal end face 12a and a curved crystal peripheral portion, and has a gentle convex shape.
- the off orientation of the SiC seed crystal 1 A facet ⁇ 0001 ⁇ plane is formed at the end of the vector indicating dW and at the crystal peripheral portion of the crystal end face 12a of the SiC single crystal 12.
- the off direction dW and the off angle ⁇ W are not particularly limited. However, in view of the current situation of device fabrication, the off direction dW is preferably in the ⁇ 11-20> direction or ⁇ 1-100. > Either direction. Further, the off angle ⁇ W should be more than 0 ° and not more than 16 °, and more preferably not less than 2 ° and not more than 8 °, because most of the substrates used for device fabrication are 4 ° off substrates. There should be.
- the off angle ⁇ W is an angle formed between the normal line n of the main surface (or surface) of the SiC seed crystal 1 and the ⁇ 0001> direction (c-axis direction).
- the off orientation dW is the direction of the n ′′ vector obtained by projecting the normal vector n ′ of the ⁇ 0001 ⁇ plane of the SiC seed crystal 1 onto the main surface (or surface) of the SiC seed crystal 1.
- the growth surface at the growth peripheral portion has a curved surface in the process of growing the SiC single crystal 12.
- the means for making the growth surface at the growth center portion flatter than the growth peripheral portion is a method of controlling the shape of the growth surface of the SiC single crystal by adjusting the diameter of the heat removal hole of the heat insulating material covering the lid of the crucible to which the SiC seed crystal is attached.
- the ingot surface shape of the SiC single crystal is a convex shape, and the facet ⁇ 0001 ⁇ plane is formed substantially at the center of the crystal end surface of the SiC single crystal.
- the diameter ⁇ of the heat removal hole of the heat insulating material is preferably 40% or more of the diameter ⁇ of the SiC seed crystal. % Or less, more preferably 60% or more and 80% or less.
- the growth surface at the growth peripheral portion have a curved surface and the growth surface at the growth central portion flatter than the growth peripheral portion
- a heat insulating material covering the crucible lid Compared with the part corresponding to the growth peripheral part, the thermal conductivity of the crucible lid made of a graphite member or the like corresponding to the thin part of the heat insulating material corresponding to the growth central part corresponds to the growth peripheral part.
- a method for controlling the surface shape of the ingot can be exemplified by adjusting the temperature distribution during crystal growth by increasing the height of the portion corresponding to the center of growth compared to the portion.
- the facet ⁇ 0001 ⁇ plane is formed at the crystal peripheral portion of the crystal end face where the bulk SiC single crystal has grown as described above, and the growth is performed prior to the main growth process for performing the main crystal growth.
- a growth sub-process that uses different growth conditions from the main process. That is, a growth sub-process with a growth atmosphere pressure of 3.9 kPa to 39.9 kPa and a seed crystal temperature of 2100 ° C. to less than 2300 ° C. is included after the nitrogen concentration is higher than that of the main growth step.
- the reason for including such a growth sub-process is to reduce the screw dislocation by structurally converting a part of the screw dislocation in the SiC single crystal into a stacking fault. Details are as described below.
- SiC crystal growth in the sublimation recrystallization method generally includes “step flow growth centering on facets” and “spiral growth centering on threading screw dislocations”. That is, as shown in FIG. 5, the main crystal growth is step flow growth, but in order to increase the growth rate in the growth direction indicated by the arrow in FIG. 5 (that is, the macro growth direction). In addition to step flow growth at facets, spiral growth centering on threading screw dislocations is required.
- the screw dislocations are reduced because, as shown in FIG. 6A, the screw dislocations are covered with high steps, so that the extension direction of the dislocations is deflected by 90 degrees and converted into stacking faults. It is thought to do.
- the step overlap occurs by inhibiting the lateral extension of the step (step bunching), and the high step. Is formed.
- the method of inhibiting the horizontal extension of a step was used by increasing the amount of nitrogen (N) on a terrace. That is, in order to increase the amount of N on the terrace, in addition to increasing the nitrogen partial pressure in the growth atmosphere, the growth rate should be suppressed so that step flow growth due to the progress of the terrace becomes the dominant condition. To do.
- N nitrogen
- FIG. 7B not only a high step is formed by overlapping of steps, but also a wide terrace is formed, and the amount of N increases on the wide terrace.
- the extension of is further inhibited. Therefore, it is considered that as the distance from the facet increases, that is, the distance from the facet increases, a higher step is easily formed, and the reduction of the screw dislocation is remarkably exhibited.
- the nitrogen concentration in the growth sub-process is 3.9 kPa to 39.9 kPa (30 Torr to 300 Torr), preferably 13.3 kPa or more.
- the temperature is 39.9 kPa or less (100 Torr or more and 300 Torr or less), and the temperature of the seed crystal is 2100 ° C. or more and less than 2300 ° C., preferably 2200 ° C. or more and less than 2300 ° C.
- the growth atmospheric pressure of the growth sub-process is less than 3.9 kPa, the growth rate becomes faster and spiral growth becomes dominant, and the reduction of screw dislocation does not appear effectively. On the contrary, if it exceeds 39.9 kPa, growth occurs. There is a problem with productivity because the speed is significantly reduced.
- the temperature of the seed crystal is lower than 2100 ° C., the growth rate is lowered, which causes a problem in productivity. On the other hand, if the temperature is 2300 ° C. or higher, the growth rate is increased. Not expressed.
- the nitrogen concentration in the growth sub-process is preferably 2 ⁇ 10 19 cm ⁇ from the viewpoint of suppressing the formation of two-dimensional nuclei on a large terrace while more reliably inhibiting the lateral extension of the step. 3 to 1 ⁇ 10 20 cm ⁇ 3 , more preferably 4 ⁇ 10 19 cm ⁇ 3 to 1 ⁇ 10 20 cm ⁇ 3 and higher than the nitrogen concentration in the main growth step. To adjust.
- the crystal growth rate in the growth sub-process is preferably grown so that the crystal growth rate is 0.1 mm / h or less, more preferably 0.05 mm / h or less. It is good.
- the nitrogen concentration in the crystal obtained in the growth subprocess is higher than that in the main growth process, it is not suitable as a product when considered for general device applications.
- the shorter time is desirable from the viewpoint of productivity, and the crystal growth rate in the growth sub-process is preferably 0.01 mm / h or more.
- the thickness of the crystal grown in the growth sub-process is preferably 1 mm or more, more preferably 3 mm in order to more reliably obtain the effect of reducing the screw dislocation by the structural transformation as described above. That's it.
- the thickness of the crystal grown in this growth sub-process By increasing the thickness of the crystal grown in this growth sub-process, the structural transformation from screw dislocations to stacking faults can be made more reliably, so the thickness is not limited, but the effect is saturated and productivity etc.
- the upper limit of the thickness of the crystal grown in the growth sub-process can be 10 mm.
- the crystal growth is performed by the main growth process in which the main crystal growth is performed.
- the main growth step for performing the main crystal growth is a step for performing main crystal growth in the method of the present invention, and specifically, a step for obtaining a thickness of more than 50% of the obtained SiC single crystal. Or a process that occupies more than 50% of the crystal growth time in the growth time of the SiC single crystal, or a process in which the crystal growth rate is the fastest among the processes of growing the SiC single crystal, Any one or more of the above are satisfied.
- the SiC single crystal is mainly grown by lowering the growth atmosphere pressure and increasing the temperature of the seed crystal by increasing the crystal growth rate as compared with the growth sub-process.
- Specific growth conditions can be the same as the growth conditions of a SiC single crystal by a general sublimation recrystallization method.
- the growth atmosphere pressure is preferably 0.13 kPa to 2.6 kPa (1 Torr to 20 Torr), more preferably 0.65 kPa to 1.95 kPa (5 Torr to 15 Torr).
- the temperature of the seed crystal in the main growth step is higher than the temperature of the seed crystal in the growth sub-step, but it is lower than 2400 ° C., more preferably 2200 ° C. or higher and 2400 ° C. or lower.
- the nitrogen concentration in the growth main process can be appropriately set except that it is lower than the nitrogen concentration in the growth sub-process.
- the nitrogen concentration in the crystal is 2 ⁇ 10 18 cm ⁇ 3 or more. It is preferable to set it to 1 ⁇ 10 20 cm ⁇ 3 or less.
- the semi-insulating SiC single crystal may be obtained by cutting off the nitrogen supply.
- the crystal growth rate in this main growth step is preferably 0.1 mm or more per hour, and more preferably 0.3 mm / hr or more.
- the thickness of the SiC single crystal grown in the main growth process is preferably at least 10 mm in consideration of producing a SiC single crystal ingot according to the present invention and taking out the SiC single crystal substrate from this. Preferably it is 30 mm or more.
- the upper limit of the crystal growth rate in the main growth process is about 1.0 mm / hr, and the upper limit of the thickness of the SiC single crystal grown in the main growth process is about 100 mm. It is.
- the pressure when switching from the growth sub-process to the growth main process, the pressure is preferably reduced at a pressure change rate of 12 kPa or less per hour, and more preferably 1 kPa or less per hour. Good.
- the larger the change width per unit time the larger the amount of change in the growth rate over time, and it is possible that the crystal growth during that time becomes unstable. It can be reliably excluded.
- the temperature when switching the growth temperature, the temperature is preferably increased at a temperature change rate of 40 ° C. or less per hour, and more preferably 10 ° C. or less per hour.
- the screw dislocation is reduced by using the structural transformation of dislocations, there is no limitation on the polytype of the obtained SiC single crystal, and typical polytypes of 4H type, 6H type, and 3C type are available. It can be applied as a method for obtaining a silicon carbide single crystal. In particular, it is advantageous in that it can be applied to the 4H type, which is considered to be promising as a power device application.
- the screw dislocations in the present invention can be reduced by controlling the growth conditions by the sublimation recrystallization method, there is no limitation on the crystal diameter of the obtained SiC single crystal. Therefore, the present invention can be applied to a crystal growth process having a diameter of 50 mm or more and 300 mm or less, which is considered most promising at the present time.
- part of the screw dislocations in the SiC single crystal is converted into stacking faults in the growth sub-process, so that the crystal end face of the SiC single crystal obtained in the main growth process
- a facet ⁇ 0001 ⁇ plane is formed at the peripheral edge of the crystal, and the screw dislocation density is reduced in a region having a predetermined distance from the facet ⁇ 0001 ⁇ plane.
- the SiC single crystal substrate has a facet ⁇ 0001 ⁇ plane at the substrate peripheral portion of the substrate surface on the end point side of the vector indicating the off orientation.
- the SiC single crystal substrate has a steep dislocation density when the distribution of the screw dislocation density is determined along the substrate diameter away from the facet ⁇ 0001 ⁇ plane toward the start point of the off-direction vector. Has a decreasing distribution boundary. That is, at the distribution boundary, the reduction rate of the screw dislocation density increases rapidly.
- the SiC single crystal substrate of the present invention has a dislocation distribution boundary where the screw dislocation density suddenly decreases, as shown in the examples described later. More specifically, the SiC single crystal substrate according to an embodiment of the present invention has a screw dislocation density distribution when the distribution of screw dislocation density is determined along the substrate diameter starting from the center of the facet ⁇ 0001 ⁇ plane. It has a dislocation distribution boundary whose value is 75% or less with respect to the value of the screw dislocation density in the facet ⁇ 0001 ⁇ plane of the SiC single crystal substrate.
- a more preferred embodiment of the SiC single crystal substrate of the present invention has a screw dislocation density distribution determined along a straight line having an angle of + 45 ° to the substrate diameter in a direction away from the center of the facet ⁇ 0001 ⁇ plane.
- Any distribution of the screw dislocation density obtained along a straight line having an angle of ⁇ 45 ° with respect to the substrate diameter in the direction away from the center of the facet ⁇ 0001 ⁇ plane has a distribution boundary at which the screw dislocation density drops sharply.
- the screw dislocation is reduced in the region opposite to the facet ⁇ 0001 ⁇ plane across the distribution boundary of the screw dislocation density, and the screw dislocation density is preferably about 1 to 300 / cm 2 . Can be reduced. If such a SiC single crystal substrate is used, a high-quality SiC device can be obtained with a high yield.
- FIG. 1 is an apparatus for producing a bulk SiC single crystal used to obtain the SiC single crystal of the present invention, and shows an example of an apparatus for growing a single crystal by an improved Rayleigh method (sublimation recrystallization method). Crystal growth is performed by sublimating the SiC raw material 2 by induction heating and recrystallizing it on the SiC seed crystal 1.
- the SiC seed crystal 1 is attached to the inner surface of a crucible lid 4 that forms a graphite crucible, and the SiC raw material 2 is filled in a crucible container body 3 that also forms a graphite crucible.
- This graphite crucible is installed on a graphite support rod 6 inside a double quartz tube 5 by covering both the crucible container body 3 and the crucible lid 4 with a graphite felt (heat insulating material) 7 for heat shielding. Then, after the inside of the double quartz tube 5 is evacuated by the evacuation device 11, high purity Ar gas and nitrogen gas are introduced into the quartz tube via the pipe 9 while being controlled by the mass flow controller 10, and the pressure inside the quartz tube (growth atmosphere) is increased. While adjusting the pressure) with the vacuum evacuation device 11, a high-frequency current was passed through the work coil 8 to heat the graphite crucible, and crystal growth was performed.
- an optical path having a diameter of 2 to 4 mm is provided at the center of the crucible lid 4 so that the radiation light can be extracted, and the temperature of the SiC seed crystal 1 is measured using a two-color thermometer (not shown). It was set as the growth temperature.
- Example 1 First, from a previously obtained SiC single crystal having a 100 mm diameter (0001) plane as a main surface, the off-direction of the (0001) plane is the ⁇ 11-20> direction, and the off-angle of the (0001) plane is 4H SiC single crystal substrate was cut out so as to be 4 degrees, and the cut surface was mirror-polished to prepare a seed crystal.
- the SiC seed crystal 1 was attached to the inner surface of the crucible lid 4 of the single crystal growth apparatus described above, set in the crucible container body 3 of the graphite crucible filled with the SiC raw material 2, and covered with the graphite felt 7.
- the graphite felt 7 covering the crucible lid 4 is provided with a heat removal hole (not shown) having a diameter of 50 mm so as to be concentric with the SiC single crystal attached to the inner surface of the crucible lid 4.
- the growth surface in the process of growing the SiC single crystal 12 has a curved surface at the growth peripheral portion, and is flatter than the growth peripheral portion at the growth central portion. I did it.
- the graphite crucible (the crucible container body 3 and the crucible lid body 4) covered with the graphite felt 7 was placed on the graphite support rod 6 and installed inside the double quartz tube 5.
- the pressure is reduced at a pressure change rate of 1.2 kPa / hr, and the temperature is increased at a temperature change rate of 10 ° C./hr, the growth atmosphere pressure is 1.3 kPa, the temperature of the SiC seed crystal 1 is 2300 ° C.
- Crystal growth was performed for 100 hours while maintaining the nitrogen concentration of about 1 ⁇ 10 19 cm ⁇ 3 (growth main process).
- the nitrogen concentration (nitrogen atom number density) in the crystal was determined by secondary ion mass spectrometry (SIMS) described in Jpn. J. Appl. Phys. Vol. 35 (1996) pp. 2240-2243.
- the bulk SiC single crystal (ingot) obtained by the growth sub-process and the growth main process has a flat crystal center part at the crystal end face, a curved surface at the crystal peripheral part, and a smooth ingot outer shape. A convex shape was shown, the diameter was about 100 mm, and the highest crystal height was about 33 mm.
- the thickness (height) of the single crystal grown in the growth sub-process is 3 mm when estimated from the results of other production examples grown under the same conditions for each process, and the single crystal grown in the growth main process The thickness (height) is considered to be 30 mm.
- this dark brown region is a facet ⁇ 0001 ⁇ plane, has a major axis of approximately 15 mm and a minor axis of approximately 10 mm, and the center of the facet at which the major axis and minor axis intersect is It was located at a distance of about 5 mm from the outer periphery of the crystal end face of the SiC single crystal to the center side along the crystal end face.
- SiC single crystal having a thickness of 400 ⁇ m, a diameter of 100 mm, a main surface formed such that the off orientation of the (0001) plane is the ⁇ 11-20> direction and the off angle of the (0001) plane is 4 degrees A substrate was obtained.
- This SiC single crystal substrate is immersed in molten KOH at 520 ° C.
- the dislocation density at the measurement point on the direction (ii) from the center of the facet 13a toward the opposite circumferential portion at an angle of 45 ° clockwise from the direction (i) which is the diameter direction of the substrate i)
- the dislocation density at the measurement point on the (iii) direction from the center of the facet 13a toward the opposite circumferential portion at an angle of 45 ° in the counterclockwise direction from the direction is the same as that in the (i) direction.
- the dislocation density was obtained and the dislocation distribution was examined. Note that the measurement points are shown as black circles in the figure.
- the dislocation density at each measurement point was determined from the number of etch pits in a 4 mm ⁇ 3 mm region from the center.
- the screw dislocation density is measured at the measurement point whose distance from the facet 13a is 50 mm. It decreases to about 1/2 to 2/3 of the screw dislocation density at the boundary. Since the screw dislocation density decreases steeply in this way, it is considered that the region between the measurement point having a distance of 40 mm and the measurement point having a distance of 50 mm from the facet 13a corresponds to the distribution boundary of the screw dislocation density. Further, as shown in FIG. 8, it can be said that the region 13b opposite to the facet 13a across the distribution boundary 14 of the screw dislocation density is a region in which screw dislocations are extremely reduced.
- the (1-100) plane substrate 15 is cut out using the SiC single crystal 12 cut out from the SiC single crystal substrate 13 so as to include the approximate center of the facet 13a at the crystal end face 12a of the SiC single crystal 12.
- dislocation defects and stacking faults were observed by X-ray topography. That is, the longitudinal section of the SiC single crystal 12 obtained in Example 1 was observed with an X-ray topograph.
- Example 2 The nitrogen concentration in the crystal in the growth sub-process was set to about 1 ⁇ 10 20 cm ⁇ 3, and the nitrogen concentration in the crystal in the main growth step was set to about 1 ⁇ 10 19 cm ⁇ 3 .
- a bulk SiC single crystal (ingot) according to Example 2 was obtained in the same manner as Example 1 except for the above.
- the bulk SiC single crystal (ingot) obtained by the growth sub-process and the growth main process has a flat crystal center part at the crystal end face, a curved surface at the crystal peripheral part, and a smooth ingot outer shape. A convex shape was shown, the diameter was about 100 mm, and the highest crystal height was about 33 mm.
- the thickness (height) of the single crystal grown in the growth sub-process is 3 mm when estimated from the results of other production examples grown under the same conditions for each process, and the single crystal grown in the growth main process The thickness (height) is considered to be 30 mm.
- this dark brown region is a facet ⁇ 0001 ⁇ plane, has a major axis of approximately 15 mm and a minor axis of approximately 10 mm, and the center of the facet at which the major axis and minor axis intersect is It was located at a distance of about 5 mm from the outer periphery of the crystal end face of the SiC single crystal to the center side along the crystal end face.
- SiC single crystal having a thickness of 400 ⁇ m, a diameter of 100 mm, a main surface formed such that the off orientation of the (0001) plane is the ⁇ 11-20> direction and the off angle of the (0001) plane is 4 degrees A substrate was obtained.
- the screw dislocation density was measured by the same method as in Example 1.
- Comparative Example 1 The nitrogen concentration in the crystal in the growth sub-process was set to about 5 ⁇ 10 18 cm ⁇ 3, and the nitrogen concentration in the crystal in the main growth step was set to about 1 ⁇ 10 19 cm ⁇ 3 .
- a bulk SiC single crystal (ingot) according to Comparative Example 1 was obtained in the same manner as Example 1 except for the above.
- the shape and height of the obtained bulk SiC single crystal are almost the same as those in Examples 1 and 2, and the thickness (height) of each single crystal grown in the growth sub-process and the growth main process. ) Is considered the same. Further, the facet ⁇ 0001 ⁇ plane at the crystal end face of the obtained SiC single crystal was also the same as in Examples 1 and 2 in terms of size and position.
- a SiC single crystal substrate having a thickness of 400 ⁇ m, a diameter of 100 mm, an off orientation of the (0001) plane being the ⁇ 11-20> direction, and an off angle of the (0001) plane of 4 degrees was obtained.
- the screw dislocation density was measured by the same method as in Example 1.
- the SiC single crystal 12 left after cutting out the SiC single crystal substrate 13 is used so as to include the approximate center of the facet 13a on the crystal end face 12a of the SiC single crystal 12 (1- 100)
- the surface substrate 15 was cut out and mirror-polished, and then dislocation defects and stacking faults were observed by X-ray topography, and an X-ray topography photograph was taken with the diffraction surface of the X-ray topograph as the (0004) plane. From the X-ray topographic photograph, it was observed that threading screw dislocations extended parallel to the growth direction, and almost no conversion into stacking faults was observed.
- Example 2 A heat removal hole having a diameter of 20 mm is provided so as to be concentric with the SiC single crystal attached to the inner surface of the crucible lid 4, and the nitrogen concentration in the crystal in the growth sub-process is about 1 ⁇ 10 20 cm ⁇ 3.
- the bulk SiC according to Comparative Example 2 is used. A single crystal (ingot) was obtained.
- the bulk SiC single crystal (ingot) obtained by the growth sub-process and the growth main process had a curved surface from the center of the crystal to the periphery of the crystal, and the ingot had a gentle convex shape.
- the shape and height of the obtained bulk SiC single crystal (ingot) are almost the same as those in Example 1, and the thickness (height) of each single crystal grown in the growth sub-process and the growth main process is also the same. The same is considered. Further, when the end face (crystal end face) in the crystal growth direction of the obtained SiC single crystal was observed, an area having a strong dark brown contrast was confirmed at the crystal peripheral portion of the crystal end face.
- this dark brown region is a facet ⁇ 0001 ⁇ plane, has a major axis of approximately 15 mm and a minor axis of approximately 10 mm, and the center of the facet at which the major axis and minor axis intersect is
- the SiC single crystal was located approximately at the center of the crystal end face at a distance of about 45 mm from the outer periphery of the crystal end face to the center side along the crystal end face.
- SiC single crystal having a thickness of 400 ⁇ m, a diameter of 100 mm, a main surface formed such that the off orientation of the (0001) plane is the ⁇ 11-20> direction and the off angle of the (0001) plane is 4 degrees A substrate was obtained.
- the screw dislocation density was measured by the same method as in Example 1.
Abstract
Description
(1)坩堝容器本体と坩堝蓋体とを有した坩堝の坩堝蓋体に炭化珪素からなる種結晶を配置し、坩堝容器本体に炭化珪素原料を配置して、炭化珪素原料を昇華させて種結晶上にバルク状の炭化珪素単結晶を成長させる炭化珪素単結晶の製造方法であって、前記種結晶が{0001}面からオフ方位にオフ角を有しており、前記バルク状の炭化珪素単結晶が成長した結晶端面の結晶周縁部にファセット{0001}面を形成すると共に、得られるSiC単結晶の50%超の厚みを得る結晶成長を行う成長主工程に先駆けて、前記成長主工程よりも窒素濃度を高めて、成長雰囲気圧力が3.9kPa以上39.9kPa以下、種結晶の温度が2100℃以上2300℃未満で結晶成長させる成長副工程を含めることを特徴とする炭化珪素単結晶の製造方法。
(2)成長副工程での結晶成長速度が0.1mm/h以下であることを特徴とする(1)に記載の炭化珪素単結晶の製造方法。
(3)成長副工程での結晶中の窒素濃度が2×1019cm-3以上1×1020cm-3以下であることを特徴とする(1)又は(2)に記載の炭化珪素単結晶の製造方法。
(4)成長主工程は、結晶中での窒素濃度が1×1018cm-3以上1×1020cm-3以下、成長雰囲気圧力が0.13kPa以上2.6kPa以下、種結晶の温度が成長副工程よりも高くて2400℃未満であることを特徴とする(1)~(3)のいずれかに記載の炭化珪素単結晶の製造方法。
(5)バルク状の炭化珪素単結晶が成長していく過程での成長表面が、成長周縁部では曲面を有し、成長中央部では成長周縁部に比べて平坦となるように、前記バルク状の炭化珪素単結晶を前記種結晶の主面上に形成することによって、前記ファセット{0001}面を形成することを特徴とする(1)~(4)のいずれかに記載の炭化珪素単結晶の製造方法。
(6)前記成長副工程において、前記バルク状の炭化珪素単結晶の厚みが1mm以上増加するまで前記バルク状の炭化珪素単結晶を成長させることによって、成長副工程において炭化珪素単結晶中のらせん転位の一部が積層欠陥に構造変換し、炭化珪素単結晶の結晶端面におけるファセット{0001}面から離隔した領域でのらせん転位密度が減少する(1)~(5)のいずれかに記載の炭化珪素単結晶の製造方法。
(7){0001}面からオフ方位へオフ角を有する炭化珪素単結晶基板であって、オフ方位を示すベクトルの終点側において基板表面の基板周縁部にファセット{0001}面を有し、前記ファセット{0001}面から前記オフ方位を示すベクトルの始点方向への基板直径に沿ったらせん転位密度の分布において、らせん転位密度の減少率が急激に大きくなるらせん転位密度の分布境界が存在することを特徴とする炭化珪素単結晶基板。
(8)前記基板直径に対して+45°の角度を有する直線に沿ったらせん転位密度の分布と、前記基板直径に対して-45°の角度を有する直線に沿ったらせん転位密度の分布には、いずれもらせん転位密度が急峻に落ち込むらせん転位密度の分布境界が存在することを特徴とする(7)に記載の炭化珪素単結晶基板。
本発明の製造方法は、坩堝容器本体と坩堝蓋体とを有した坩堝の坩堝蓋体に炭化珪素からなる種結晶(SiC種結晶)を配置し、坩堝容器本体内にSiC原料を配置して、SiC原料を昇華させてSiC種結晶上にバルク状のSiC単結晶を成長させるSiC単結晶の製造方法である。また、前記SiC種結晶は、{0001}面の法線が主面(或いは表面)上において所定のオフ方位へ向くように前記{0001}面と前記主面とが所定のオフ角を形成するように切り出されている。また、本発明の製造方法は、前記バルク状のSiC単結晶が成長した結晶端面の結晶周縁部にファセット{0001}面を形成すると共に、主たる結晶成長を行う成長主工程に先駆けて、成長主工程とは異なる成長条件を採用した成長副工程を含めるようにする。
先ず、予め得られた口径100mmの(0001)面を主面としたSiC単結晶から、前記(0001)面のオフ方位が<11-20>方向であって、前記(0001)面のオフ角が4度になるように、4H型のSiC単結晶基板を切り出し、切り出された面を鏡面研磨して種結晶を準備した。このSiC種結晶1を上記で説明した単結晶成長装置の坩堝蓋体4の内面に取り付け、SiC原料2を充填した黒鉛製坩堝の坩堝容器本体3にセットし、黒鉛製フェルト7で被覆した。その際、坩堝蓋体4を覆う黒鉛製フェルト7には、坩堝蓋体4の内面に取り付けたSiC単結晶と同心円状になるように、口径50mmの抜熱孔(図示外)を設けることで、図4(b)に示したように、SiC単結晶12が成長していく過程での成長表面が、成長周縁部では曲面を有し、成長中央部では成長周縁部に比べて平坦となるようにした。そして、黒鉛製フェルト7で被覆した黒鉛製坩堝(坩堝容器本体3及び坩堝蓋体4)を黒鉛支持棒6の上に載せて、二重石英管5の内部に設置した。
成長副工程での結晶中の窒素濃度が約1×1020cm-3となるようにすると共に、成長主工程での結晶中の窒素濃度が約1×1019cm-3となるようにした以外は実施例1と同様にして、実施例2に係るバルク状のSiC単結晶(インゴット)を得た。
成長副工程での結晶中の窒素濃度が約5×1018cm-3となるようにすると共に、成長主工程での結晶中の窒素濃度が約1×1019cm-3となるようにした以外は実施例1と同様にして、比較例1に係るバルク状のSiC単結晶(インゴット)を得た。
坩堝蓋体4の内面に取り付けたSiC単結晶と同心円状になるように、口径20mmの抜熱孔を設け、また、成長副工程での結晶中の窒素濃度が約1×1020cm-3となるようにすると共に、成長主工程での結晶中の窒素濃度が約1×1019cm-3となるようにした以外は実施例1と同様にして、比較例2に係るバルク状のSiC単結晶(インゴット)を得た。
Claims (8)
- 坩堝容器本体と坩堝蓋体とを有した坩堝の坩堝蓋体に炭化珪素からなる種結晶を配置し、坩堝容器本体に炭化珪素原料を配置して、炭化珪素原料を昇華させて種結晶上にバルク状の炭化珪素単結晶を成長させる炭化珪素単結晶の製造方法であって、
前記種結晶が{0001}面からオフ方位にオフ角を有しており、
前記バルク状の炭化珪素単結晶が成長した結晶端面の結晶周縁部にファセット{0001}面を形成すると共に、得られるSiC単結晶の50%超の厚みを得る結晶成長を行う成長主工程に先駆けて、前記成長主工程よりも窒素濃度を高めて、成長雰囲気圧力が3.9kPa以上39.9kPa以下、種結晶の温度が2100℃以上2300℃未満で結晶成長させる成長副工程を含めることを特徴とする炭化珪素単結晶の製造方法。 - 成長副工程での結晶成長速度が0.1mm/h以下であることを特徴とする請求項1に記載の炭化珪素単結晶の製造方法。
- 成長副工程での結晶中の窒素濃度が2×1019cm-3以上1×1020cm-3以下であることを特徴とする請求項1又は2に記載の炭化珪素単結晶の製造方法。
- 成長主工程は、結晶中での窒素濃度が1×1018cm-3以上1×1020cm-3以下、成長雰囲気圧力が0.13kPa以上2.6kPa以下、種結晶の温度が成長副工程よりも高くて2400℃未満であることを特徴とする請求項1~3のいずれか1項に記載の炭化珪素単結晶の製造方法。
- バルク状の炭化珪素単結晶が成長していく過程での成長表面が、成長周縁部では曲面を有し、成長中央部では成長周縁部に比べて平坦となるように、前記バルク状の炭化珪素単結晶を前記種結晶の主面上に形成することによって、前記ファセット{0001}面を形成することを特徴とする請求項1~4のいずれか1項に記載の炭化珪素単結晶の製造方法。
- 前記成長副工程において、前記バルク状の炭化珪素単結晶の厚みが1mm以上増加するまで前記バルク状の炭化珪素単結晶を成長させることによって、成長副工程において炭化珪素単結晶中のらせん転位の一部が積層欠陥に構造変換し、炭化珪素単結晶の結晶端面におけるファセット{0001}面から離隔した領域でのらせん転位密度が減少する請求項1~5のいずれか1項に記載の炭化珪素単結晶の製造方法。
- {0001}面からオフ方位へオフ角を有する炭化珪素単結晶基板であって、
オフ方位を示すベクトルの終点側において基板表面の基板周縁部にファセット{0001}面を有し、
前記ファセット{0001}面から前記オフ方位を示すベクトルの始点方向への基板直径に沿ったらせん転位密度の分布において、らせん転位密度の減少率が急激に大きくなるらせん転位密度の分布境界が存在することを特徴とする炭化珪素単結晶基板。 - 前記基板直径に対して+45°の角度を有する直線に沿ったらせん転位密度の分布と、前記基板直径に対して-45°の角度を有する直線に沿ったらせん転位密度の分布には、いずれもらせん転位密度が急峻に落ち込むらせん転位密度の分布境界が存在することを特徴とする請求項7に記載の炭化珪素単結晶基板。
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CN107002281B (zh) | 2019-06-04 |
JPWO2016088883A1 (ja) | 2017-09-14 |
US10711369B2 (en) | 2020-07-14 |
EP3228733A1 (en) | 2017-10-11 |
KR101936007B1 (ko) | 2019-01-07 |
EP3228733B1 (en) | 2021-09-29 |
US20170342593A1 (en) | 2017-11-30 |
EP3228733A4 (en) | 2017-11-22 |
CN107002281A (zh) | 2017-08-01 |
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JP6584428B2 (ja) | 2019-10-02 |
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