Sapphire substrate and method for manufacturing the same and nitride semiconductor light emitting element

• US 8,957,433 B2
• Filed: 03/14/2013
• Issued: 02/17/2015
• Est. Priority Date: 03/28/2012
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Sako, Naoya, Inoue, Yoshiki, Ohara, Takashi, Shibutani, Yuki, Kawauchi, Yoshihito, Takeichi, Kazuyuki, Nagahama, Yasunori
• Primary Examiner(s): HA, NATHAN W
• Application Number:
  US13/804,453
• Publication Number:
  US 20140061661A1
• Time in Patent Office: 705 Days
• Field of Search: 257 76- 80
• US Class Current: 257/95
• CPC Class Codes: C30B 25/183 being provided with a buffer layer, e.g. a lattice matching layer
• CPC Class Codes: C30B 25/186 being specially pre-treated by, e.g. chemical or physical means
• CPC Class Codes: C30B 29/20 Aluminium oxides
• CPC Class Codes: C30B 29/403 AIII-nitrides
• CPC Class Codes: C30B 29/406 Gallium nitride
• CPC Class Codes: C30B 33/08 Etching
• CPC Class Codes: C30B 33/10 in solutions or melts
• CPC Class Codes: C30B 33/12 in gas atmosphere or plasma
• CPC Class Codes: H01L 21/02002 Preparing wafers
• CPC Class Codes: H01L 21/308 using masks H01L21/3063, H01L21/3065 take precedence
• CPC Class Codes: H01L 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/24 of the light emitting region, e.g. non-planar junction
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

A sapphire substrate provided with a plurality of projections on a principal surface on which a nitride semiconductor is grown to form a nitride semiconductor light emitting element. The projections have a substantially triangular pyramidal-shape the projections having a plurality of side surfaces and a pointed top. The side surfaces have an inclination angle of between 53° and 59° from a bottom of the projections. The side surfaces are crystal-growth suppressed surfaces on which a growth of the nitride semiconductor is suppressed relative to a portion of the principal surface located between adjacent projections. A bottom of the projections has a substantially triangular shape having three outwardly curved arc-shaped sides, and each of the side surfaces has a substantially triangular shape having vertexes located at the top of the projection and at both ends of a respective side of the bottom of the projection.

Claims

1. A sapphire substrate provided with a plurality of projections on a principal surface on which a nitride semiconductor is grown to form a nitride semiconductor light emitting element,

wherein the projections have a substantially triangular pyramidal-shape the projections having a plurality of side surfaces and a pointed top,

wherein the side surfaces have an inclination angle of between 53°

and 59°

from a bottom of the projections, and

wherein the side surfaces are crystal-growth-suppressed surfaces on which a growth of the nitride semiconductor is suppressed relative to a portion of the principal surface located between adjacent projections,

wherein a bottom of the projections has a substantially triangular shape having three outwardly curved arc-shaped sides, and each of the side surfaces has a substantially triangular shape having vertexes located at the top of the projection and at both ends of a respective side of the bottom of the projection, and

wherein the projections are arranged on vertexes of a triangular lattice, and an orientation of the bottom of said projections conforms with an orientation that is rotated by about 30 degrees from an orientation of a triangle of the triangular lattice.

2. The sapphire substrate according to claim 1, wherein the projections have a height of between 1.0 and 1.7 μ

m.

3. The sapphire substrate according to claim 1, wherein the projections are separated from each other on the principal surface of the sapphire substrate.

4. The sapphire substrate according to claim 1, wherein the projections are arranged periodically on the principal surface of the sapphire substrate.

5. The sapphire substrate according to claim 1, wherein a distance between tops of the adjacent projections is between 2.2 μ

m and 3.1 μ

m.

6. The sapphire substrate according to claim 5, wherein the distance between tops of the adjacent projections is between 2.8 μ

m and 3.1 μ

m.

7. The sapphire substrate according to claim 1, wherein the portion of the principal surface located between the adjacent projections is a crystal growth surface, and wherein a ratio of an area of the crystal growth surface to an area of the principal surface is between 25% and 60%.

8. The sapphire substrate according to claim 7, wherein the ratio of the area of the crystal growth surface to that of the principal surface is between 30% and 45%.