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US-12628396-B2 - Silicon carbide substrate and method of manufacturing silicon carbide substrate

US12628396B2US 12628396 B2US12628396 B2US 12628396B2US-12628396-B2

Abstract

A silicon carbide substrate includes a first main surface, a second main surface, a threading screw dislocation, and a blind scratch. The second main surface is located opposite to the first main surface. The threading screw dislocation extends to each of the first main surface and the second main surface. The blind scratch is exposed at the first main surface and extends linearly as viewed in a direction perpendicular to the first main surface. A value obtained by dividing an area density of the blind scratch by an area density of threading screw dislocation is smaller than 0.13.

Inventors

  • Kyoko Okita
  • Tsubasa Honke
  • Shunsaku UETA

Assignees

  • SUMITOMO ELECTRIC INDUSTRIES, LTD.

Dates

Publication Date
20260512
Application Date
20211124
Priority Date
20210312

Claims (7)

  1. 1 . A silicon carbide substrate comprising: a first main surface; a second main surface located opposite to the first main surface; a threading screw dislocation extending to each of the first main surface and the second main surface; and a blind scratch exposed at the first main surface and extending linearly as viewed in a direction perpendicular to the first main surface, wherein a value obtained by dividing an area density of the blind scratch by an area density of the threading screw dislocation is smaller than 0.13.
  2. 2 . The silicon carbide substrate according to claim 1 , wherein the area density of the blind scratch is determined using a mirror electron microscope while the first main surface is irradiated with an ultraviolet ray, and the area density of the threading screw dislocation is determined using molten potassium hydroxide, and the area density of the blind scratch is determined under a condition that an interval between measurement regions in the first main surface measured with the mirror electron microscope is 614 μm, and the measurement regions each have a square shape with each side of 80 μm.
  3. 3 . The silicon carbide substrate according to claim 1 , wherein the area density of the threading screw dislocation is 1,000/cm 2 or less.
  4. 4 . The silicon carbide substrate according to claim 3 , wherein the area density of the threading screw dislocation is 500/cm 2 or less.
  5. 5 . The silicon carbide substrate according to claim 1 , wherein the area density of the blind scratch is 60/cm 2 or less.
  6. 6 . A method of manufacturing a silicon carbide substrate, the method comprising: preparing a silicon carbide single-crystal substrate; and performing chemical mechanical polishing on the silicon carbide single-crystal substrate using colloidal silica as abrasive grains, wherein when a grain size at which a cumulative value of a grain size distribution of the colloidal silica corresponds to 10% is a first grain size, a grain size at which the cumulative value of the grain size distribution of the colloidal silica corresponds to 50% is a second grain size, and a grain size at which the cumulative value of the grain size distribution of the colloidal silica corresponds to 90% is a third grain size, the first grain size is 20 nm to 40 nm, the second grain size is 1.2 times or more the first grain size, and the third grain size is 0.85 times to 1.15 times a sum of the first grain size and the second grain size.
  7. 7 . The method of manufacturing a silicon carbide substrate according to claim 6 , wherein, in the performing chemical mechanical polishing on the silicon carbide single-crystal substrate using colloidal silica as abrasive grains, the silicon carbide single-crystal substrate is vacuum-suctioned to a polishing head with a cushioning member between the silicon carbide single-crystal substrate and the polishing head, and a value obtained by multiplying a Shore A hardness of the cushioning member by a compression ratio of the cushioning member is 1,000 degree % or more.

Description

TECHNICAL FIELD The present disclosure relates to a silicon carbide substrate and a method of manufacturing the silicon carbide substrate. This application claims priority based on Japanese Patent Application No. 2021-039845 filed on Mar. 12, 2021. The entire contents of the Japanese patent application are incorporated herein by reference. BACKGROUND ART Japanese Unexamined Patent Application Publication No. 2016-139685 (PTL 1) describes a single-crystal silicon carbide substrate having a roughness Ra of 1 nm or less and having blind scratches. CITATION LIST Patent Literature PTL 1: Japanese Unexamined Patent Application Publication No. 2016-139685 SUMMARY OF INVENTION A silicon carbide substrate according to an embodiment of the present disclosure includes a first main surface, a second main surface, a threading screw dislocation, and a blind scratch. The second main surface is located opposite to the first main surface. The threading screw dislocation extends to each of the first main surface and the second main surface. The blind scratch is exposed at the first main surface and extends linearly as viewed in a direction perpendicular to the first main surface, A value obtained by dividing an area density of the blind scratch by an area density of the threading screw dislocation is smaller than 0.13. A method of manufacturing a silicon carbide substrate according to an embodiment of the present disclosure includes the following steps. A silicon carbide single-crystal substrate is prepared. Chemical mechanical polishing is performed on the silicon carbide single-crystal substrate using colloidal silica as abrasive grains. When a grain size at which a cumulative value of a grain size distribution of the colloidal silica corresponds to 10% is a first grain size, a grain size at which the cumulative value of the grain size distribution of the colloidal silica corresponds to 50% is a second grain size, and a grain size at which the cumulative value of the grain size distribution of the colloidal silica corresponds to 90% is a third grain size, the first grain size is 20 nm to 40 nm, the second grain size is 1.2 times or more the first grain size, and the third grain size is 0.85 times to 1.15 times a sum of the first grain size and the second grain size. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic plan view showing the configuration of a silicon carbide substrate according to an embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view taken along line II-II of FIG. 1. FIG. 3 is an enlarged plan view of region III of FIG. 1. FIG. 4 is a schematic cross-sectional view taken along line IV-IV of FIG. 3. FIG. 5 is an enlarged plan view of region V of FIG. 1. FIG. 6 is a schematic cross-sectional view taken along line VI-VI of FIG. 5. FIG. 7 is an enlarged plan view of region VII of FIG. 1. FIG. 8 is a schematic cross-sectional view taken along line VIII-VIII of FIG. 7. FIG. 9 is a schematic diagram showing a configuration of a mirror electron microscope. FIG. 10 is a schematic view showing a portion where a mirror electron image is captured. FIG. 11 is a schematic view showing a mirror electron image of a blind scratch. FIG. 12 is a flow diagram schematically showing a method of manufacturing a silicon carbide substrate according to an embodiment of the present disclosure. FIG. 13 is a schematic cross-sectional view showing preparing a silicon carbide single-crystal substrate. FIG. 14 is a schematic view showing performing chemical mechanical polishing on a silicon carbide single-crystal substrate. DETAILED DESCRIPTION Problem to be Solved by the Present Disclosure It is an object of the present disclosure to provide a silicon carbide substrate and a method of manufacturing a silicon carbide substrate that can inhibit the generation of carrot defects in a silicon carbide epitaxial layer. Advantageous Effects of the Present Disclosure According to the present disclosure, it is possible to provide a silicon carbide substrate and a method of manufacturing a silicon carbide substrate that can inhibit the generation of carrot defects in a silicon carbide epitaxial layer. DESCRIPTION OF EMBODIMENTS (1) A silicon carbide substrate 100 according to an embodiment of the present disclosure includes a first main surface 1, a second main surface 2, a threading screw dislocation 21, and a blind scratch 30. Second main surface 2 is located opposite to first main surface 1. Threading screw dislocation 21 extends to each of first main surface 1 and second main surface 2. Blind scratch 30 is exposed at first main surface 1 and extends linearly as viewed in a direction perpendicular to first main surface 1. A value obtained by dividing an area density of blind scratch 30 by an area density of threading screw dislocation 21 is smaller than 0.13.(2) In silicon carbide substrate 100 according to (1), the area density of blind scratch 30 may be determined using a mirror electron microscope while first main