Nitride semiconductor crystal with surface texture

• US 8,658,440 B2
• Filed: 12/06/2011
• Issued: 02/25/2014
• Est. Priority Date: 08/28/2006
• Status: Active Grant

• Current Assignee: Stanley Electric Company Limited
• Original Assignee: Stanley Electric Company Limited
• Inventors: Liang, Ji-Hao, Tsuchiya, Masahiko, Chinone, Takako, Kajikawa, Masataka
• Primary Examiner(s): Nguyen, Cuong Q
• Assistant Examiner(s): YUSHINA, GALINA G
• Application Number:
  US13/311,644
• Publication Number:
  US 20120077298A1
• Time in Patent Office: 812 Days
• Field of Search: 257/79, 257/89, 257/95, 257/103, 257/E33.001, 257/E33.005, 257/E33.008, 257/E33.025, 257/E33.028, 257/E21.023, 257/E21.024, 257/E21.025, 257/E21.027, 257/E21.028, 438/22, 438/758, 438/759, 438/942, 438/948
• US Class Current: 438/22
• CPC Class Codes: H01L 33/0075 comprising nitride compounds
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• 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 nitride semiconductor light emitting device is formed by: forming a resist pattern on a first nitride semiconductor layer formed on a substrate, the resist pattern having a region whose inclination angle relative to a substrate surface changes smoothly as viewed in a cross section perpendicular to the substrate surface; etching the substrate by using the resist pattern as a mask to transfer the resist pattern to the first nitride semiconductor layer; and forming an light emitting layer on the patterned first nitride semiconductor layer. The nitride semiconductor light emitting device can emit near-white light or have a wavelength range generally equivalent to or near visible light range.

Claims

1. A method for manufacturing a nitride semiconductor light emitting device, the method comprising:

forming a resist pattern on a first nitride semiconductor layer formed above a substrate, wherein said resist pattern has a plurality of projections, wherein adjacent ones of said projections are continuous with each other, and wherein an inclination angle of an upper surface of said resist pattern relative to a substrate surface changes smoothly between said adjacent projections;

etching said first nitride semiconductor layer by using said resist pattern as a mask to transfer said resist pattern to said first nitride semiconductor layer; and

forming an active layer on said patterned first nitride semiconductor layer;

wherein said active layer includes a multiple quantum well structure including a plurality of well layers, and wherein a maximum inclination angle of an upper surface of a lower well layer is steeper than a maximum inclination angle of an upper well layer.

2. The method according to claim 1, wherein said projections are disposed in a hexagonal close-packed configuration.

3. The method according to claim 1, wherein said projections are rib-like stripes.

4. The method according to claim 1, wherein an inclination angle of an upper surface of said first nitride semiconductor layer changes in a range of 0°

to 30°

after said etching of said first nitride semiconductor layer,

wherein said active layer contains GaN, and includes a first region and a second region, and

wherein an inclination angle along an a-axis direction of an upper surface of said first region changes in a range of 0°

to 3°

, and inclination angle along an m-axis direction of an upper surface of said second region changes in a range of 0°

to 30°

.

5. The method according to claim 1, wherein forming the resist pattern comprises:

coating a resist layer on said first nitride semiconductor layer; and

radiating light on said resist layer by using proximity exposure and developing said resist layer to form said resist pattern.

6. The method for manufacturing a nitride semiconductor light emitting device according to claim 5, wherein said active layer includes an n-type nitride semiconductor layer, a p-type nitride semiconductor layer, and a plurality of light emitting regions having different light emission wavelength ranges.

7. The method according to claim 6, wherein said inclination angle is from 0°

to 90°

.

8. A method for manufacturing a nitride semiconductor crystal, the method comprising:

forming a resist pattern on a first nitride semiconductor layer formed above a substrate, wherein said resist pattern has a plurality of projections, wherein adjacent ones of said projections are continuous with each other, and wherein an inclination angle of an upper surface of said resist pattern relative to a substrate surface changes smoothly between said adjacent projections;

etching said first nitride semiconductor layer by using said resist pattern as a mask to transfer said resist pattern to said first nitride semiconductor layer; and

forming an active layer on said patterned first nitride semiconductor layer;

wherein said active layer includes a multiple quantum well structure including a plurality of well layers, and wherein a maximum inclination angle of an upper surface of a lower well layer is steeper than a maximum inclination angle of an upper well layer.

9. The method according to claim 8, wherein forming the resist pattern comprises:

coating a resist layer on said first nitride semiconductor layer; and

radiating light on said resist layer by using proximity exposure and developing said resist layer to form said resist pattern.

10. The method according to claim 9, wherein said active layer includes an n-type nitride semiconductor layer, a p-type nitride semiconductor layer, and a plurality of light emitting regions having different light emission wavelength ranges.