SAPPHIRE SUBSTRATE AND SEMICONDUCTOR

• US 20120074431A1
• Filed: 08/05/2011
• Published: 03/29/2012
• Est. Priority Date: 08/06/2010
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: NARITA, Junya, Wakai, Yohei, Inoue, Yoshiki, Kadan, Katsuyoshi, Okada, Takuya, Sako, Naoya
• Granted Patent: US 9,012,936 B2
• Time in Patent Office: Days
• US Class Current: 257/79
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/0243 Surface structure
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: Y10T 428/24 Structurally defined web or sheet [e.g., overall dimension, etc.]
• CPC Class Codes: Y10T 428/24479 including variation in thickness

Abstract

The sapphire substrate has a principal surface for growing a nitride semiconductor to form a nitride semiconductor light emitting device and comprising a plurality of projections of the principal surface, wherein an outer periphery of a bottom surface of each of the projections has at least one depression. This depression is in the horizontal direction. The plurality of projections are arranged so that a straight line passes through the inside of at least any one of projections when the straight line is drawn at any position in any direction in a plane including the bottom surfaces of the plurality of projections.

Claims

1. A sapphire substrate having a principal surface for growing a nitride semiconductor to form a nitride semiconductor light emitting device, the sapphire substrate comprising a plurality of projections on the principal surface,

wherein an outer periphery of a bottom surface of each of the projections has at least one depression.

2. The sapphire substrate according to claim 1,

wherein the plurality of projections are arranged so that a straight line passes through the inside of at least any one of projections when the straight line is drawn at any position in any direction in a plane including the bottom surfaces of the plurality of projections.

3. The sapphire substrate according to claim 1,

wherein each of the projections has a substantially polygonal cone shape or substantially polygonal truncated pyramidal shape whose bottom surface has a substantially polygonal shape, and each side of the bottom surface includes a depression in the center.

4. The sapphire substrate according to claim 1,

wherein the plurality of projections are arranged so that one of vertexes of the bottom surface of one projection of neighboring projections is located in a region defined by connecting points of two vertexes of the bottom surface of the other projection and the deepest point of the depression.

5. The sapphire substrate according to claim 4,

wherein said one projection of the neighboring projections is arranged so that the deepest portion of a depression of the other projection is located on an extended line of a line that bisect an angle of a vertex of said one projection.

6. The sapphire substrate according to claim 1, wherein each of projections has a shape with linear symmetry to a straight line that connects a depression to a vertex opposite to the side including the depression.

7. The sapphire substrate according to claim 1, wherein each of the projections has a top surface that has a shape substantially similar to that of the bottom surface.

8. The sapphire substrate according to claim 1, wherein each of the projections has a bottom surface in a shape of substantially triangle.

9. The sapphire substrate according to claim 8, wherein the plurality of projections are arranged so as to form a plurality of rows, and wherein the plurality of projections are arranged so that a bisector that bisects an angle of one of vertexes of projections arranged in the same line is located on a straight line, and the projection direction defined by the direction, in which the bisector faces outside from the inside of projections, becomes the same.

10. The sapphire substrate according to claim 9, wherein a direction of the projections forming one row of neighboring rows is opposite to a direction of the projections forming the other of the neighboring rows.

11. The sapphire substrate according to claim 1, wherein a group composed of (n+1) number of projections arranged at vertexes and a center of a substantially regular n-sided polygon, is repeatedly arranged.

12. The sapphire substrate according to claim 11, wherein the neighboring groups of the groups share a part of the projection.

13. The sapphire substrate according to claim 8, wherein sides of each of the bottom surfaces of projections respectively have the depression in the center and wherein the directions toward outside from the inside of the bottom surfaces of the projections are respectively adjusted within a range of ±

10 degrees of the direction in which the axis “

a”

is rotated clockwise by 30 degrees.

14. The sapphire substrate according to claim 8, wherein sides of each of the bottom surfaces of projections respectively have the depression in the center and wherein the directions toward outside from the inside of the bottom surfaces of the projections are respectively adjusted within a range of ±

10 degrees of the direction in which the axis “

a”

is rotated counter clockwise by 30 degrees.

15. The sapphire substrate according to claim 8, wherein sides of each of the bottom surfaces of projections respectively have the depression in the center and wherein the directions toward outside from the inside of the bottom surfaces of the projections are adjusted within a range of ±

10 degrees of the axis “

a”

.

16. The sapphire substrate according to claim 8, wherein each of the projections is separated in a center of the projection so as to be composed of three sub-projections each elongating in one direction of three directions from the center.

17. The sapphire substrate according to claim 16, wherein the three directions are respectively positioned within a range of ±

10 degrees of the direction in which the axis “

a”

is rotated clockwise by 30 degrees.

18. The sapphire substrate according to claim 16, wherein the three directions are respectively positioned within a range of ±

10 degrees of the direction in which the axis “

a”

is rotated counter clockwise by 30 degrees.

24. A semiconductor light emitting device which is a nitride semiconductor layer light emitting device is formed by growing a nitride semiconductor on one principal surface of the sapphire substrate according to claim 1.

19. A sapphire substrate having a principal surface for growing a nitride semiconductor to form a nitride semiconductor light emitting device, the sapphire substrate comprising a plurality of projections on the principal surface,

wherein a bottom surface of each of the projections has a substantially triangle shape, and each side of the bottom surface has a depression in the center, and

wherein the directions toward outside from the inside of the bottom surfaces of the projections are respectively adjusted within a range of ±

10 degrees of the direction in which the axis “

a”

is rotated clockwise by 30 degrees.

20. A sapphire substrate having a principal surface for growing a nitride semiconductor to form a nitride semiconductor light emitting device, the sapphire substrate comprising a plurality of projections on the principal surface,

wherein a bottom surface of each of the projections has a substantially triangle shape, and each side of the bottom surface has a depression in the center, and

wherein the directions toward outside from the inside of the bottom surfaces of the projections are respectively adjusted within a range of ±

10 degrees of the axis “

a”

.

21. A sapphire substrate having a principal surface for growing a nitride semiconductor to form a nitride semiconductor light emitting device, the sapphire substrate comprising a plurality of projections on the principal surface, wherein each of the projections is separated in a center of the projection so as to be composed of three sub-projections elongating in one direction of three directions from the center.

22. The sapphire substrate according to claim 21, wherein the three directions are respectively positioned within a range of ±

10 degrees of the direction in which the axis “

a”

is rotated clockwise by 30 degrees.

23. The sapphire substrate according to claim 21, wherein the three directions are respectively positioned within a range of ±

10 degrees of the direction in which the axis “

a”

is rotated counter clockwise by 30 degrees.