Nitride semiconductor element and method for manufacturing the same

• US 9,525,105 B2
• Filed: 04/23/2015
• Issued: 12/20/2016
• Est. Priority Date: 04/25/2014
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Shimooka, Tomohiro
• Primary Examiner(s): TAYLOR, EARL N
• Application Number:
  US14/694,792
• Publication Number:
  US 20150311388A1
• Time in Patent Office: 607 Days
• US Class Current: 1/1
• 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 21/02658 Pretreatments cleaning in general H01L21/02041
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/12 with a stress relaxation structure, e.g. buffer layer
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

A method of manufacturing a nitride semiconductor element includes dry etching a main surface of a sapphire substrate at a c-plane side thereof, using a mask provided on the main surface, to form a plurality of projections, each having a circular bottom surface; wet etching the sapphire substrate to form an upper part of each projection into a triangular pyramid shape while maintaining the circular bottom surface of the projection; and growing a semiconductor layer made of a nitride semiconductor on a dry etched surface and a wet etched surface of the sapphire substrate.

Claims

1. A method of manufacturing a nitride semiconductor element, the method comprising:

dry etching a main surface of a sapphire substrate at a c-plane side thereof, with a mask provided on the main surface, thus forming a plurality of projections, each projection having a circular bottom surface;

wet etching the sapphire substrate, thus forming an upper part of each projection into a triangular pyramid shape while maintaining the circular bottom surface of each projection; and

growing a semiconductor layer made of a nitride semiconductor on the sapphire substrate after said dry etching and wet etching.

2. The method according to claim 1, wherein a height of the upper part of the projection is 10% or more of an overall height of the projection.

3. The method according to claim 1, wherein a side surface of a lower part of the projection is a curved surface formed in a conical or dome shape.

4. The method according to claim 1, further comprising:

forming a buffer layer on the sapphire substrate after said wet etching the sapphire substrate and before growing the semiconductor layer.

5. A method of manufacturing a nitride semiconductor element, the method comprising:

preparing a sapphire substrate with a plurality of projections formed on a surface of the sapphire substrate at a c-plane side thereof, each of the projections having a circular bottom surface and an upper part in a triangular pyramid shape, a ridge line of the triangular pyramid shape extending in a direction of an m-axis in a top view; and

growing a semiconductor layer made of a nitride semiconductor on the surface of the sapphire substrate.

6. The method according to claim 5, further comprising:

forming a buffer layer on the surface of the sapphire substrate before growing the semiconductor layer.

7. The method according to claim 5, wherein a height of the upper part of the projection is 10% or more of an overall height of the projection.

8. The method according to claim 5, wherein a side surface of a lower part of the projection is a curved surface formed in a conical or dome shape.

9. A nitride semiconductor element comprising:

a sapphire substrate with a plurality of projections disposed on a surface thereof at a c-plane side; and

a semiconductor layer made of a nitride semiconductor and disposed on the surface of the sapphire substrate, wherein

each projection has a circular bottom surface, and an upper part in a triangular pyramid shape, and

each ridge line of the triangular pyramid shape extends in a direction of an m-axis in a top view.

10. The nitride semiconductor element according to claim 9, wherein

a height of the upper part of the projection is 10% or more of an overall height of the projection.