JP7415810B2 - SiC ingot manufacturing method and SiC ingot - Google Patents

Description

The present invention relates to a method for manufacturing a SiC ingot and a SiC ingot.

Silicon carbide (SiC) has a dielectric breakdown field one order of magnitude larger and a band gap three times larger than silicon (Si). Furthermore, silicon carbide (SiC) has characteristics such as a thermal conductivity that is approximately three times higher than that of silicon (Si). Silicon carbide (SiC) is expected to be applied to power devices, high-frequency devices, high-temperature operation devices, and the like.

BACKGROUND ART SiC epitaxial wafers, in which an epitaxial film is formed on a SiC wafer, are used for devices such as semiconductors. An epitaxial film formed on a SiC wafer by chemical vapor deposition (CVD) becomes an active region of a SiC semiconductor device. SiC wafers are obtained by processing SiC ingots.

The SiC ingot can be produced by a method such as a sublimation recrystallization method (hereinafter referred to as a sublimation method). The sublimation method is a method of obtaining a large single crystal by recrystallizing a raw material gas sublimated from a raw material on a seed crystal. In order to obtain a high-quality SiC ingot, a method for suppressing defects and heterogeneous polymorphism (the coexistence of crystals with different polytypes) is required.

For example, Patent Document 1 describes that the generation of different polymorphisms can be suppressed by matching the c-plane facet and the screw dislocation generation region. The c-plane facet is a portion where the c-plane is exposed on the crystal growth surface. Crystal growth in the c-plane facet behaves differently from step-flow growth in a portion having an offset angle with respect to the c-plane. In the c-plane facet, heterogeneous polymorphism is likely to occur. By introducing screw dislocations into the c-plane facets where heterogeneous polymorphism is likely to occur, generation of heterogeneous polymorphism is suppressed.

Patent No. 4924290

However, as the diameter of SiC ingots increases, the position of c-plane facets on the crystal growth plane changes. The c-plane facets migrate toward the outer periphery of the SiC ingot as the crystal grows, and may deviate from the region where screw dislocations occur due to artificial defects. In addition, if the convexity of the SiC ingot is increased to prevent the c-plane facets from migrating toward the outer circumference of the SiC ingot as the crystal grows, the stress generated within the SiC ingot will increase, causing cracks and basal plane dislocations (c-plane There is a problem in that the frequency of occurrence of slips increases.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing an SiC ingot that can suppress the occurrence of heterogeneous polymorphism and crystal defects, and an SiC ingot obtained by the method.

The present inventor has discovered that by increasing the curvature of the SiC ingot only on the upstream side of the offset where c-plane facets occur, it is possible to control the position where c-plane facets are formed and suppress the increase in stress generated within the SiC ingot. I found out.
That is, the present invention provides the following means to solve the above problems.

(1) The method for manufacturing a SiC ingot according to the first aspect provides an SiC ingot having an offset angle of 2° or more and 6° or less in the first direction and having an artificial defect on the first end side in the first direction and a diameter of 6 inches or more. and a growth step of growing a single crystal on a first surface of the seed crystal, and in the growth step, the diameter of the single crystal changes as the crystal grows. The growth step is divided into a first half of growth in which the amount of growth at the center of the seed crystal in the first direction is less than 8 mm, and a second half of growth after the first half of growth. In this step, the amount of growth at the first end in the first direction is smaller than the amount of growth at the second end opposite to the first end in the first direction.

(2) In the method for manufacturing a SiC ingot according to the above aspect, in the growth step, the center of a heating device surrounding the seed crystal may be shifted toward the second end from the center of the seed crystal.

(3) In the method for manufacturing a SiC ingot according to the above aspect, the growth step includes a step of installing the seed crystal on an installation surface of a crucible, and opening an opening in a surface opposite to the installation surface through a wall of the crucible. installing a heat insulating material having a section, the center of the opening of the heat insulating material may be shifted toward the second end with respect to the center of the seed crystal.

(4) The SiC ingot according to the second aspect is a seed crystal having a diameter of 6 inches or more and having an offset angle of 2° or more and 6° or less in the first direction and having an artificial defect on the first end side in the first direction. and a single crystal laminated on a first surface of the seed crystal, the single crystal increasing in diameter from the first surface of the seed crystal in the stacking direction, and The height of the first end relative to the first surface is 1 mm or more lower than the height of the second end opposite to the first end relative to the first surface.

(5) In the SiC ingot according to the above aspect, the height of the center of the single crystal in the first direction with respect to the first surface is higher than the height of the first end and the second end with respect to the first surface. Good too.

(6) In the SiC ingot according to the above aspect, the curvature of the curve connecting the center of the single crystal in the first direction and the first end is the same as the curvature of the curve connecting the center of the single crystal in the first direction and the second end. may be larger than the curvature of the curve connecting them.

(7) In the SiC ingot according to the above aspect, the artificial defect may be located within 25% of the diameter of the seed crystal from the first end of the seed crystal.

The method for manufacturing a SiC ingot according to the above embodiment can suppress the occurrence of different polymorphisms and crystal defects. The SiC ingot according to the above embodiment has few heterogeneous polymorphisms and crystal defects, and can efficiently obtain a high-quality SiC wafer.

FIG. 2 is a cross-sectional view of a SiC ingot in the growing process. FIG. 2 is a plan view of a SiC ingot in the growing process. FIG. 3 is a diagram schematically showing a first method. FIG. 3 is a diagram schematically showing a first method. FIG. 3 is a diagram schematically showing a second method. FIG. 3 is an enlarged view of the main part of the SiC ingot on the first end side in the x direction. FIG. 3 is a diagram showing the difference in crystal growth between c-plane facets and other parts. FIG. 3 is a diagram showing crystal growth when a screw dislocation exists in a c-plane facet. 3 is a cross-sectional view of a SiC ingot in the growth process according to Comparative Example 1. FIG. It is a sectional view of the SiC ingot concerning this embodiment.

Hereinafter, this embodiment will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may show characteristic parts enlarged for convenience, and the dimensional ratio of each component may differ from the actual one. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited thereto, and can be practiced with appropriate changes within the scope of the invention.

First, let's define direction. The direction from the seed crystal 10 to the single crystal 20, which will be described later, is the z direction, and one direction perpendicular to the z direction is the x direction. The x direction is a direction in which the crystal plane of the seed crystal 10 is inclined at a predetermined offset angle with respect to the first surface 10A. The x direction is an example of a first direction, and is sometimes referred to as an offset direction. The y direction is a direction perpendicular to the x direction and the z direction.

“SiC ingot manufacturing method”
The method for manufacturing a SiC ingot according to the first embodiment includes a preparation step and a growth step. FIG. 1 is a cross-sectional view of a SiC ingot 100 in the growing process. FIG. 2 is a plan view of the SiC ingot in the growing process. FIG. 1 is a cross section taken along the AA plane in FIG. In the SiC ingot 100, a single crystal 20 is grown on the first surface 10A of the seed crystal 10.

The preparation process is a process of preparing the seed crystal 10. The seed crystal 10 is a SiC single crystal of 6 inches or more. The crystal plane of the seed crystal 10 is inclined at a predetermined offset angle in the x direction with respect to the first surface 10A of the seed crystal 10. The predetermined offset angle is, for example, 2° or more and 6° or less. The seed crystal 10 has an artificial defect 11 on the first end 10a side in the x direction. The artificial defect 11 is located within 25% of the diameter of the seed crystal 10 from the first end 10a of the seed crystal 10, for example. Artificial defect 11 is formed on first surface 10A of seed crystal 10.

The artificial defect 11 is a part where the crystal structure is disordered compared to other parts. The artificial defect 11 is formed on the surface (first surface 10A) of the seed crystal 10 by, for example, machining, ion implantation, or the like. The artificial defect 11 serves as a starting point for generating screw dislocations during the crystal growth process. When crystal growth is performed on a portion where the crystal structure is disordered, crystal growth occurs while the disorder of the crystal structure is resolved. For example, disturbances in the <0001> direction parallel to the growth direction are converted into screw dislocations, micropipes, Frank-type stacking faults, etc. having Burgers vectors parallel to <0001> and are eliminated. Disturbances in the <11-20> and <1-100> directions perpendicular to the growth direction are converted into threading edge dislocations, basal plane dislocations, Shockley-type stacking faults, etc. that have Burgers vectors in those directions. and resolve it.

The growth step is a step of growing the single crystal 20 on the first surface 10A of the seed crystal 10. In the growth process, the diameter of the single crystal 20 is increased from the diameter of the seed crystal 10 as the crystal grows. The crystal diameter can be increased, for example, by controlling the flow of sublimation gas to the single crystal 20 using a tapered member or the like in a sublimation method. The diameter of the single crystal 20 after crystal growth is, for example, 2 mm or more larger than the diameter of the seed crystal 10.

The growth process is divided into the first half of growth and the second half of growth. The first half of growth refers to growth until the growth amount h3 at the center 10c of the seed crystal 10 in the x direction is less than 8 mm. The second half of growth refers to growth in which the growth amount h3 at the center 10c of the seed crystal 10 in the x direction is 8 mm or more. The center 10c is the intersection of the center line c1 in the x direction and the first surface 10A, and is the center of the first surface 10A of the seed crystal 10 in the x direction. The growth amount h3 is the height of a perpendicular line drawn from the center 20c of the single crystal 20 in the x direction to the first surface 10A of the seed crystal 10 in the growth process. Here, the center 20c is the intersection of the center line c1 in the x direction and the crystal growth surface 20A. The first half of growth is the initial stage of crystal growth, and crystal growth is not stabilized. In the latter half of growth, crystal growth becomes stable and can be controlled by adjusting the conditions of the growth space.

In the method for manufacturing a SiC ingot according to this embodiment, in the second half of growth, the growth amount h1 at the first end 20a of the single crystal 20 is made smaller than the growth amount h2 at the second end 20b. The first end 20a is the end in the x direction of the single crystal 20 on the side where the artificial defect 11 is provided. The second end 20b is the end of the single crystal 20 opposite to the first end 20a in the x direction. If the crystal growth surface 20A and the side surface 20B of the single crystal 20 are continuously connected and the first end 20a and the second end 20b cannot be clearly defined, from the outermost position in plan view from the z direction. The positions that are 1 mm inside are defined as the first end 20a and the second end 20b.

The difference Δh between the growth amount h1 at the first end 20a and the growth amount h2 at the second end 20b is preferably 1.0 mm or more, more preferably 1.5 mm or more, and still more preferably 2.0 mm or more. be.

Although there are no particular limitations on how to make the growth amount h1 at the first end 20a smaller than the growth amount h2 at the second end 20b, there are various methods. Some methods will be exemplified below.

First, the first method will be explained. 3 and 4 are diagrams schematically showing the first method. SiC ingots are manufactured, for example, by a sublimation method. The manufacturing apparatus shown in FIGS. 3 and 4 includes a crucible 30, a rotating table 40, and a heating device 50.

The crucible 30 can have a seed crystal 10 and a raw material 31 installed therein. Seed crystal 10 is placed at a position facing raw material 31 . The single crystal 20 is obtained by sublimating the raw material 31 and recrystallizing it on the first surface 10A of the seed crystal 10. The crucible 30 is supported by a rotating table 40 and rotates as the rotating table 40 rotates. A heating device 50 surrounds the crucible 30 .

In the first method, the center of the heating device 50 surrounding the seed crystal 10 is shifted from the center of the seed crystal 10 toward the second end 20b. That is, the center line c2 of the heating device 50 is shifted from the center line c1 of the seed crystal 10 toward the second end 20b. The center line c2 of the heating device 50 is the central axis of the area surrounded by the heating device 50 when viewed from the z direction. The single crystal 20 grows along an isothermal surface. The isothermal surface is approximately symmetrical in the x and y directions with respect to the center line c2 of the heating device 50. When the centerline c2 of the heating device 50 and the centerline c1 of the seed crystal 10 are shifted, the isothermal surface in the vicinity of the crystal growth surface 20A becomes asymmetrical with respect to the centerline c1. As a result, the crystal growth on the second end 20b side near the center line c2 of the heating device 50 is promoted more than the crystal growth on the first end 20a, and the amount of growth h1 on the first end 20a is changed from the amount of growth on the second end 20b. It becomes smaller than h2.

FIG. 3 shows an example of the first method, in which a seed crystal 10 is placed at the center of a crucible 30, and the center line c1 of the seed crystal 10, together with the crucible 30, is shifted with respect to the center line c2 of the heating device 50. FIG. 4 is another example of the first method, in which the center line c1 of the seed crystal 10 is moved relative to the center line c2 of the heating device 50 by shifting the position where the seed crystal 10 is installed from the center of the crucible 30. It's shifted.

Next, the second method will be explained. FIG. 5 is a diagram schematically showing the second method. FIG. 5(a) is a perspective view of a manufacturing apparatus in the second method, and FIG. 5(b) is a sectional view of the manufacturing apparatus in the second method.

The manufacturing apparatus shown in FIG. 5 includes a crucible 30 and a heat insulating material 60. The crucible 30 is surrounded by a heating device as in FIGS. 3 and 4. First, similar to the first method, the seed crystal 10 is placed inside the crucible 30. The seed crystal 10 is placed at the center of the crucible 30 (at a position overlapping the center line of the heating device). Next, a heat insulating material 60 is installed in the crucible 30. The heat insulating material 60 is installed inside the crucible 30 at a position opposite to the installation surface 30A on which the seed crystal 10 is installed via the wall of the crucible 30. The heat insulating material 60 has an opening 60A. The center of the opening 60A is shifted toward the second end 20b with respect to the center of the seed crystal 10. That is, the center line c3 of the opening 60A is shifted toward the second end 20b with respect to the center line c1 of the seed crystal 10.

As described in the first method, the single crystal 20 grows along an isothermal surface. When the heat insulating material 60 having the opening 60A asymmetrical with respect to the centerline c1 of the seed crystal 10 is installed in the crucible 30, the isothermal surface within the crucible 30 becomes asymmetrical with respect to the centerline c1. As a result, the crystal growth on the second end 20b side near the center line c3 of the opening 60A is promoted more than the crystal growth on the first end 20a, and the growth amount h1 at the first end 20a is changed from the growth amount h1 at the second end 20b. It becomes smaller than h2.

In addition, the shape of the tapered member that controls the flow of gas to the single crystal 20 may be made asymmetrical with respect to the center line c1, or a part of the pedestal on which the seed crystal 10 is installed may be processed to form the seed crystal. The distance between the first surface 10A of the crystal 10 and the raw material 31 may be changed depending on the position in the x direction.

Further, it is preferable that the growth amount h3 of the single crystal 20 at the center 20c in the x direction of the single crystal 20 is larger than the growth amounts h1 and h2 at the first end 20a and the second end 20b. The crystal growth surface 20A becomes convex, and the generation of defects can be suppressed.

The growth amount h3 at the center 20c of the single crystal 20 is preferably 2% or more larger than the growth amount h1 at the first end 20a, and more preferably 5% or more and 12% or less larger than the growth amount h1 at the first end 20a. do. The growth amount h3 at the center 20c of the single crystal 20 is preferably 1% or more larger than the growth amount h2 at the second end 20b, and more preferably 4% or more and 11% or less larger than the growth amount h2 at the second end 20b. . By controlling the growth amounts h1, h2, and h3 of the first end 20a, second end 20b, and center 20c, the shape of the crystal growth surface 20A can be controlled. The growth amounts h1, h2, and h3 at each point of the single crystal 20 can be adjusted by controlling the isothermal surface near the crystal growth surface 20A.

Further, the curvature of the crystal growth surface 20A connecting the center 20c and the first end 20a of the single crystal 20 is preferably larger than the curvature of the crystal growth surface 20A connecting the center 20c of the single crystal 20 and the second end 20b. When the difference angle between the tangent at the first end 20a and the center 20c is Δα, the difference angle between the tangent at the second end 20b and the center 20c is Δβ, and the offset angle is θ, Δα is θ<Δα It is preferable that <2θ is satisfied, and Δβ preferably satisfies 0≦Δβ<Δα. Here, the tangent at each point is the tangent at each point of a circular arc when the height difference between the first end 20a or second end 20b and the center 20c is approximated to a perfect circular arc.

The curvature of the crystal growth surface 20A connecting the center 20c and the first end 20a of the single crystal 20 influences the position of the c-plane facet during the crystal growth process. When the curvature of the crystal growth surface 20A connecting the center 20c and the first end 20a is within a predetermined range, movement of the c-plane facet into the interior of the single crystal 20 can be suppressed during the crystal growth process. The curvature of the crystal growth surface 20A connecting the center 20c and the second end 20b of the single crystal 20 affects the magnitude of stress generated inside the single crystal 20 near the second end 20b. If the curvature of the crystal growth plane 20A connecting the center 20c and the second end 20b of the single crystal 20 is large, stress generated inside the single crystal 20 becomes large, and basal plane dislocations are likely to occur due to c-plane slip or the like. Basal plane dislocations are more likely to occur near the second end 20b than near the first end 20a.

According to the method for manufacturing a SiC ingot according to the present embodiment, c-plane facets are generated inside the screw dislocation occurrence locations 22 due to the artificial defects 11 during the crystal growth process, and generation of heterogeneous polymorphism can be suppressed. Further, according to the method for manufacturing a SiC ingot according to the present embodiment, the crystal growth surface 20A is not excessively curved, and the occurrence of cracks and basal plane dislocations (c-plane slips) can be suppressed.

First, the c-plane facet will be explained. FIG. 6 is an enlarged view of the main part of the SiC ingot 100 on the first end 10a side in the x direction. A single crystal 20 is grown on the seed crystal 10. The crystal plane CS of the seed crystal 10 and the single crystal 20 is inclined in the x direction with respect to the first surface 10A at an offset angle θ. A crystal growth surface 20A of the single crystal 20 is formed in a convex shape in the z direction. When the crystal growth surface 20A is convex in the z direction, a portion of the crystal growth surface 20A is parallel to the crystal plane CS. In the crystal growth plane 20A, a plane parallel to the crystal plane CS is a c-plane facet F. The c-plane facet F is parallel to the crystal plane CS, and it can be said that the c-plane ((0001) plane) is exposed. In the single crystal 20, the position where the c-plane facet is formed can be confirmed as a locus 21.

The crystal growth behavior of the c-plane facet F is different from that of the portion of the crystal growth surface 20A other than the c-plane facet F. FIG. 7 is a diagram showing the difference in crystal growth between the c-plane facet F and other parts. FIG. 7(a) is a diagram showing crystal growth in a step-flow growing portion, and FIG. 7(b) is a diagram showing crystal growth in a c-plane facet F.

As shown in FIG. 7(a), step flow growth occurs on the crystal growth plane 20A other than the c-plane facet F. In step flow growth, crystals grow in the a-plane direction (<11-20> direction). The single crystal 20 grows in the z direction as a whole by growing the crystal in the a-plane direction. In step flow growth, crystal growth takes over the information of the a-plane.

SiC has polymorphisms such as 3C-SiC, 4H-SiC, and 6H-SiC. The polymorphs have the same outermost surface structure when viewed from the c-plane direction (<0001> direction), but have different structures when viewed from the a-plane direction (<11-20> direction). In step flow growth, crystals grow in the a-plane direction, so polymorphism is less likely to occur.

On the other hand, as shown in FIG. 7(b), in the c-plane facet F, the c-plane is exposed. In the c-plane facet F, crystals grow in an island shape in the c-plane direction. As described above, polymorphisms of SiC cannot be distinguished in the c-plane direction, and it is not determined which crystal structure will form when a crystal grows in the c-plane direction. Therefore, polymorphism is likely to occur in the c-plane facet F.

Next, the reason why heteromorphism is suppressed when the c-plane facet F and the screw dislocation occurrence location 22 associated with the artificial defect 11 overlap will be explained. FIG. 8 is a diagram showing crystal growth when a screw dislocation SD exists in the c-plane facet F.

A screw dislocation SD is a spiral defect. When one goes around a screw dislocation, the lattice plane moves up or down by one lattice plane like a spiral staircase. A step is seen on the surface near the screw dislocation SD exposed on the crystal surface. The crystal grows spirally in the vicinity of the screw dislocation SD. In spiral growth, crystals grow in the a-plane direction, so polymorphism is less likely to occur.

The screw dislocation occurrence location 22 is a portion where screw dislocation SD is likely to occur. At the screw dislocation generation location 22, screw dislocation SD occurs because the disorder of the crystal structure caused by the artificial defect 11 is tried to be eliminated. When the positions of the screw dislocation occurrence site 22 and the c-plane facet F overlap, there is a high possibility that the screw dislocation SD exists in the c-plane facet F, and the occurrence of different polymorphisms can be suppressed.

Furthermore, the reason why c-plane facets F are generated inside the screw dislocation generation site 22 in the crystal growth process according to the method for manufacturing a SiC ingot according to the present embodiment will be explained.

FIG. 9 is a cross-sectional view of the SiC ingot in the growth process according to Comparative Example 1. In the SiC ingot 101 shown in FIG. 9, the shape of the single crystal 25 is different from that in FIG. In the single crystal 25, the first end 25a and the second end 25b have the same height in the z direction, and the growth amount h1 at the first end 25a and the growth amount h2 at the second end 25b are equal.

When the diameter of the SiC ingot increases and the height positions of the first end 25a and the second end 25b in the z direction are equal, the amount of curvature of the crystal growth surface 25A becomes smaller. When the amount of curvature of the crystal growth surface 25A is small, the position where the c-plane facet is formed approaches the first end 25a. When the single crystal 25 has an enlarged diameter relative to the seed crystal 10, the single crystal (enlarged diameter portion) is formed outside the artificial defect 11 when viewed in plan from the z direction. The enlarged diameter portion is located outside the location 22 where the screw dislocation occurs. Since screw dislocation is less likely to occur in the enlarged diameter portion, if c-plane facets are formed in the enlarged diameter portion, dissimilar polymorphism is likely to occur.

In contrast, in the SiC ingot manufacturing method according to the present embodiment, the growth amount h1 at the first end 20a of the single crystal 20 is made smaller than the growth amount h2 at the second end 20b. As a result, the curvature of the crystal growth surface 20A connecting the center 20c and the first end 20a of the single crystal 20 becomes larger than the curvature of the crystal growth surface 20A connecting the center 20c and the second end 20b of the single crystal 20, and c It is possible to suppress the surface facet from reaching the enlarged diameter portion. Furthermore, by making the curvature of the crystal growth surface 20A connecting the center 20c and the second end 20b of the single crystal 20 smaller than the curvature of the crystal growth surface 20A connecting the center 20c and the first end 20a of the single crystal 20, It is possible to suppress excessive curvature of the growth surface 20A and generation of large stress within the single crystal 20, and it is possible to suppress the occurrence of cracks and basal plane dislocations (c-plane slips).

"SiC ingot"
FIG. 10 is a cross-sectional view of the SiC ingot according to this embodiment. SiC ingot 102 shown in FIG. 10 has seed crystal 10 and single crystal 90. SiC ingot 102 shown in FIG. The SiC ingot 102 shown in FIG. 10 is obtained by crystal-growing the SiC ingot 100 shown in FIG. 1 to the end.

The height H1 of the first end 90a of the single crystal 90 is lower than the height H2 of the second end 90b. The height H1 of the first end 90a is lower than the height H2 of the second end 90b by 1.0 mm or more, preferably by 1.5 mm or more, and more preferably by 2.0 mm or more.

Moreover, it is preferable that the height H3 at the center 90c of the single crystal 90 in the x direction is higher than the heights H1 and H2 at the first end 90a and the second end 90b.

The height H3 of the center 90c is preferably 2% or more higher than the height H1 of the first end 90a, and more preferably 5% or more and 12% or less higher than the height H1 of the first end 90a. The height H3 of the center 20c is preferably 1% or more higher than the height H2 of the second end 90b, and more preferably 4% or more and 11% or less higher than the height H2 of the second end 90b.

Further, it is preferable that the curvature of the first surface 90A connecting the center 90c and the first end 90a is larger than the curvature of the first surface 90A connecting the center 90c and the second end 90b. When the difference angle between the tangent at the first end 90a and the center 90c is Δα, the difference angle between the tangent at the second end 90b and the center 90c is Δβ, and the offset angle is θ, Δα is θ<Δα It is preferable that <2θ is satisfied, and Δβ preferably satisfies 0≦Δβ<Δα. Here, the tangent at each point is the tangent at each point of a circular arc when the height difference between the first end 90a or second end 90b and the center 90c is approximated to a perfect circular arc.

In the SiC ingot 102 according to this embodiment, the locus 91 where the c-plane facet is formed overlaps with the location 92 where the screw dislocation occurs. Therefore, there is no polymorph in the single crystal 20, and defects that connect in the +x direction starting from the polymorph are suppressed. Therefore, the SiC ingot 102 according to this embodiment has few heterogeneous polymorphisms and crystal defects, and a high-quality SiC wafer can be efficiently obtained.

As mentioned above, one example of the preferred embodiment of the present invention has been described in detail, but the present invention is not limited to this embodiment, and within the scope of the gist of the present invention described within the scope of the claims. Various modifications and changes are possible.

10 Seed crystal 10a, 20a, 25a, 90a First end 10c, 20c, 25c, 90c Center 10A, 90A First surface 11 Artificial defect 20, 25, 90 Single crystal 20A, 25A, 90A Crystal growth surface 20b, 25b, 90b Second end 20B Side surfaces 21, 91 Trajectories 22, 92 Screw dislocation occurrence point 30 Crucible 30A Installation surface 31 Raw material 40 Turntable 50 Heating device 60 Insulating material 60A Openings 100, 101, 102 SiC ingot c1, c2, c3 Center line CS Crystal plane F c-plane facets h1, h2, h3 Growth amount SD Screw dislocation

Claims (7)

A preparation step of preparing a seed crystal having a diameter of 6 inches or more and having an offset angle of 2° or more and 6° or less in the first direction and having an artificial defect on the first end side in the first direction;
a growth step of growing a single crystal on the first surface of the seed crystal,
the first end has an end on the upstream side of the offset;
In the growth step, the diameter of the single crystal increases from the diameter of the seed crystal as the crystal grows;
The growth step is divided into a first half of growth in which the amount of growth at the center of the seed crystal in the first direction is less than 8 mm, and a second half of growth after the first half of growth,
In the latter half of the growth, the amount of growth at a first end in the first direction is made smaller than the amount of growth at a second end opposite to the first end in the first direction. The method for manufacturing a SiC ingot according to claim 1, wherein in the growth step, the center of a heating device surrounding the seed crystal is shifted from the center of the seed crystal toward the second end. The growth step includes:
installing the seed crystal on an installation surface of a crucible;
installing a heat insulating material having an opening on a surface opposite to the installation surface via the wall of the crucible;
The method for manufacturing a SiC ingot according to claim 1 or 2, wherein the center of the opening of the heat insulating material is shifted toward the second end with respect to the center of the seed crystal. A seed crystal having a diameter of 6 inches or more and having an offset angle of 2° or more and 6° or less in the first direction and having an artificial defect on the first end side in the first direction;
a single crystal laminated on the first surface of the seed crystal,
The single crystal has a diameter expanding in the stacking direction from the first surface of the seed crystal,
The height of the first end of the single crystal in the first direction relative to the first surface is 1 mm or more lower than the height of a second end opposite to the first end relative to the first surface,
The first end is an end on the upstream side of the offset. The SiC ingot. The SiC ingot according to claim 4, wherein the height of the center of the single crystal in the first direction relative to the first surface is higher than the height of the first end and the second end relative to the first surface. 4 . The curvature of the curve connecting the center of the single crystal in the first direction and the first end is greater than the curvature of the curve connecting the center of the single crystal in the first direction and the second end. Or the SiC ingot according to 5. The SiC ingot according to any one of claims 4 to 6, wherein the artificial defect is located within 25% of the diameter of the seed crystal from the first end of the seed crystal.

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