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

• US 9,337,390 B2
• Filed: 01/09/2015
• Issued: 05/10/2016
• Est. Priority Date: 03/28/2012
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Sako, Naoya, Ohara, Takashi, Inoue, Yoshiki, Shibutani, Yuki, Kawauchi, Yoshihito, Takeichi, Kazuyuki, Nagahama, Yasunori
• Primary Examiner(s): Ha, Nathan
• Application Number:
  US14/593,728
• Publication Number:
  US 20150115307A1
• Time in Patent Office: 487 Days
• Field of Search: 257/76, 438/44
• US Class Current: 1/1
• 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 method for manufacturing a sapphire substrate in which a plurality of projections are formed on a C-plane of the sapphire substrate by etching, includes: forming a patterned etching mask on the C-plane of the sapphire substrate; etching the sapphire substrate until the projections are formed, wherein each of the projections formed by the etching has a substantially triangular pyramidal-shape and has a plurality of side surfaces, a pointed top and a bottom, wherein the bottom of each of the projections has a substantially triangular shape having three outwardly curved arc-shaped sides. The projections are arranged on vertexes of a triangular lattice, and an orientation of the bottom of the projections conforms with an orientation that is rotated by about 30 degrees from an orientation of a triangle of the triangular lattice; and removing the etching mask from the sapphire substrate.

Claims

1. A method for manufacturing a sapphire substrate in which a plurality of projections are formed on a C-plane of the sapphire substrate by etching, comprising:

forming a patterned etching mask on the C-plane of the sapphire substrate;

etching the sapphire substrate until the projections are formed, wherein each of the projections formed by the etching has a substantially triangular pyramidal-shape and has a plurality of side surfaces, a pointed top and a bottom, wherein the bottom of each of the projections has a substantially triangular shape having three outwardly curved arc-shaped sides, and each of the plurality of side surfaces has a substantially triangular shape having vertexes located at the top of the projections and at both ends of a respective side of the bottom of the projections, and wherein the projections are arranged on vertexes of a triangular lattice, and an orientation of the bottom of the projections conforms with an orientation that is rotated by about 30 degrees from an orientation of a triangle of the triangular lattice; and

removing the etching mask from the sapphire substrate.

2. The method according to claim 1, wherein the etching is dry etching.

3. The method according to claim 2, wherein a mask material used for the patterned etching mask comprises oxide layers.

4. The method according to claim 2, wherein a mask material used for the patterned etching mask comprises metal layers.

5. The method according to claim 1, wherein the etching is wet etching.

6. The method according to claim 5, wherein a mask material used for the patterned etching mask comprises an oxide of at least one element selected from a group consisting of Si, V, Zr, Nb, Hf, Ti, Ta and Al.

7. The method according to claim 5, wherein a mask material used for the patterned etching mask comprises a nitride of at least one element selected from a group consisting of Si, B and Al.

8. The method according to claim 5, wherein a mask material used for the patterned etching mask comprises SiO₂.

9. The method according to claim 5, wherein the patterned etching mask has a circular shape.

10. The method according to claim 5, wherein an etching liquid used in the wet etching comprises phosphoric acid, pyrophosphoric acid, mixed acid of phosphoric acid and/or pyrophosphoric acid with sulfuric acid, or potassium hydroxide.

11. The method according to claim 5, wherein an etching liquid used in the wet etching comprises a mixed acid comprising sulfuric acid and phosphoric acid.

12. The method according to claim 11, wherein a mixing ratio of sulfuric acid to phosphoric acid is 3 to 2.

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

wherein each of the projections has a substantially triangular pyramidal-shape and has a plurality of side surfaces, a pointed top and a bottom, and

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

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

14. The nitride semiconductor light emitting element according to claim 13, wherein the principal surface is a C-plane of the sapphire substrate.