C-plane GaN substrate

Patent metadata

Field	Value
Publication number	US-10177217-B2
Application number	US-201715681971-A
Country	US
Kind code	B2
Filing date	Aug 21, 2017
Priority date	Feb 23, 2015
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

A C-plane GaN substrate only mildly restricts the shape and dimension of a nitride semiconductor device formed on the substrate. The variation of an off-angle on the main surface of the substrate is suppressed. In the C-plane GaN substrate: the substrate comprises a plurality of facet growth areas each having a closed ring outline-shape on the main surface; the number density of the facet growth area accompanied by a core among the plurality of facet growth areas is less than 5 cm −2 on the main surface; and, when any circular area of 4 cm diameter is selected from an area which is on the main surface and is distant by 5 mm or more from the outer peripheral edge of the substrate, the variation widths of an a-axis direction component and an m-axis direction component of an off-angle within the circular area is each 0.25 degrees or less.

First claim

The invention claimed is:

1. A C-plane GaN substrate comprising:
a main surface; and
a plurality of facet growth areas each having a closed ring outline-shape on the main surface, wherein
a number density of the facet growth area accompanied by a core among the plurality of facet growth areas is less than 5 cm −2 on the main surface,
the number density is the number of the facet growth areas accompanied by cores that are observed on the main surface in a unit area,
in any circular area of 4 cm diameter formed on the main surface inside a circle disposed at 5 mm from the outer peripheral edge of the substrate, a variation range of an off-angle with respect to an a-axis direction component and with respect to an m-axis direction component within the circular area is 0.25 degrees or less for each component, said off-angle being a tilt angle of a normal vector to the main surface with respect to a c-axis as a reference, and
the substrate includes either or both of silicon and germanium.

2. The C-plane GaN substrate according to claim 1 , wherein the substrate has a C-plane growth area lying outside the plurality of facet growth areas on the main surface.

3. The C-plane GaN substrate according to claim 1 , wherein the number density of the facet growth area accompanied by an inversion domain among the plurality of facet growth areas is 0 cm −2 on the main surface.

4. The C-plane GaN substrate according to claim 1 , wherein the sum of the areas of all the facet growth areas present on the main surface is 70% or more of the area of the main surface.

5. The C-plane GaN substrate according to claim 1 , wherein the plurality of facet growth areas are at least partially regularly arranged.

6. The C-plane GaN substrate according to claim 5 , wherein the arrangement of the facet growth areas regularly arranged among the plurality of facet growth areas is a square lattice arrangement or a triangle lattice arrangement.

7. The C-plane GaN substrate according to claim 1 , wherein the substrate has an electrical resistivity of 0.1 Ω·cm or less.

8. A method for producing a nitride semiconductor device, comprising a step of preparing the C-plane GaN substrate according to claim 1 , and a step of epitaxially growing at least one nitride semiconductor layer on the prepared C-plane GaN substrate.

9. A method for producing an epitaxial wafer, comprising a step of preparing the C-plane GaN substrate according to claim 1 , and a step of epitaxially growing at least one nitride semiconductor layer on the prepared C-plane GaN substrate.

10. The C-plane GaN substrate according to claim 1 , wherein the number density of the facet growth area corresponds to the number of dot-shaped depressions observed on the main surface in the unit area.

11. A C-plane GaN substrate having a diameter of 95 to 105 mm comprising:
a main surface; and
a plurality of facet growth areas each having a closed ring outline-shape on the main surface, wherein
a number density of the facet growth area accompanied by a core among the plurality of facet growth areas is less than 5 cm −2 on the main surface,
the number density is the number of the facet growth areas accompanied by cores that are observed on the main surface in a unit area, and
in an area on the main surface inside a circle disposed at 5 mm from the outer peripheral edge of the substrate, a variation range of an off-angle with respect to an a-axis direction component and with respect to an m-axis direction component is 0.5 degrees or less for each component, said off-angle being a tilt angle of a normal vector to the main surface with respect to a c-axis as a reference.

12. The C-plane GaN substrate according to claim 11 , wherein the substrate has a C-plane growth area lying outside the plurality of facet growth areas on the main surface.

13. The C-plane GaN substrate according to claim 11 , wherein the number density of the facet growth area accompanied by an inversion domain among the plurality of facet growth areas is 0 cm −2 on the main surface.

14. The C-plane GaN substrate according to claim 11 , wherein the sum of the areas of all the facet growth areas present on the main surface is 70% or more of the area of the main surface.

15. The C-plane GaN substrate according to claim 11 , wherein the plurality of facet growth areas are at least partially regularly arranged.

16. The C-plane GaN substrate according to claim 15 , wherein the arrangement of the facet growth areas regularly arranged among the plurality of facet growth areas is a square lattice arrangement or a triangle lattice arrangement.

17. The C-plane GaN substrate according to claim 11 , wherein the substrate is added with either or both of silicon and germanium.

18. The C-plane GaN substrate according to claim 11 , wherein the substrate has an electrical resistivity of 0.1 Ω·cm or less.

19. A method for producing a nitride semiconductor device, comprising a step of preparing the C-plane GaN substrate according to claim 11 , and a step of epitaxially growing at least one nitride semiconductor layer on the prepared C-plane GaN substrate.

20. A method for producing an epitaxial wafer, comprising a step of preparing the C-plane GaN substrate according to claim 11 , and a step of epitaxially growing at least one nitride semiconductor layer on the prepared C-plane GaN substrate.

21. A C-plane GaN substrate comprising:
a main surface; and
a plurality of facet growth areas each having a closed ring outline-shape on the main surface, wherein
a number density of the facet growth area accompanied by a core among the plurality of facet growth areas is less than 5 cm −2 on the main surface,
the number density is the number of the facet growth areas accompanied by cores that are observed on the main surface in a unit area,
in any circular area of 4 cm diameter formed on the main surface inside a circle disposed at 5 mm from the outer peripheral edge of the substrate, a variation range of an off-angle with respect to an a-axis direction component and with respect to an m-axis direction component within the circular area is 0.25 degrees or less for each component, said off-angle being a tilt angle of a normal vector to the main surface with respect to a c-axis as a reference, and
the number density of the facet growth area accompanied by an inversion domain among the plurality of facet growth areas is 0 cm −2 on the main surface.

22. A C-plane GaN substrate comprising:
a main surface; and
a plurality of facet growth areas each having a closed ring outline-shape on the main surface, wherein
a number density of the facet growth area accompanied by a core among the plurality of facet growth areas is less than 5 cm −2 on the main surface,
the number density is the number of the facet growth areas accompanied by cores that are observed on the main surface in a unit area,
in any circular area of 4 cm diameter formed on the main surface inside a circle disposed at 5 mm from the outer peripheral edge of the substrate, a variation range of an off-angle with respect to an a-axis direction component and with respect to an m-axis direction component within the circular area is 0.25 degrees or less for each component, said off-angle being a tilt angle of a normal vector to the main surface with respect to a c-axis as a reference, and
the sum of the areas of all the facet growth areas present on the main surface is 70% or more of the area of the main surface.

Assignees

• Mitsubishi Chem Corp

Inventors

• Iso Kenji
• Kimura Hiromitsu
• Saito Yuya
• Enatsu Yuuki

Classifications

• H10P14/3442

  N-type · CPC title

• H10P14/3416

  Nitrides · CPC title

• H10P14/3258

  Crystal orientation · CPC title

• H10P14/3216

  Nitrides · CPC title

• H10P14/2926

  Crystal orientations · CPC title