Semiconductor light-emitting element and method of manufacturing the same

• US 20030178626A1
• Filed: 01/17/2003
• Published: 09/25/2003
• Est. Priority Date: 01/18/2002
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Asakawa, Koji, Fujimoto, Akira, Yamashita, Atsuko, Akaike, Yasuhiko, Sugiyama, Hitoshi, Ohashi, Kenichi, Yoshitake, Shunji, Washizuka, Shoichi, Egashira, Katsumi
• Granted Patent: US 7,037,738 B2
• Time in Patent Office: Days
• US Class Current: 257/79
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers

Abstract

There is disclosed a semiconductor light-emitting element comprising a substrate having a first surface and a second surface, a semiconductor laminate formed on the first surface of the substrate and containing a light-emitting layer and a current diffusion layer having a light-extracting surface. The light-emitting element is provided with a light-extracting surface which is constituted by a finely recessed/projected surface, 90% of which is constructed such that the height of the projected portion thereof having a cone-like configuration is 100 nm or more, and the width of the base of the projected portion is within the range of 10-500 nm.

Claims

1. A semiconductor light-emitting element comprising:

a substrate having a first surface and a second surface; and

a semiconductor laminate formed on said first surface of said substrate and containing a light-emitting layer and a current diffusion layer;

wherein said light-emitting element is provided with a light-extracting surface which is constituted by a finely recessed/projected surface, 90% of which is constructed such that the height of the projected portion thereof having a cone-like configuration is 100 nm or more, and the width of the base of the projected portion is within the range of 10-500 nm.

2. The semiconductor light-emitting element according to claim 1, wherein said light-extracting surface is constituted by said second surface of substrate.

3. The semiconductor light-emitting element according to claim 2, wherein said substrate is formed of a transparent substrate

4. The semiconductor light-emitting element according to claim 1, wherein said light-extracting surface is constituted by an outermost surface of said semiconductor laminate.

5. The semiconductor light-emitting element according to claim 1, wherein at least one of said projected portions is formed of a cone-shaped configuration having an apex angle ranging from 20 to 80 degrees.

6. The semiconductor light-emitting element according to claim 1, wherein at least one of said projected portions is provided, at the apex thereof, with a very small transparent portion constituted by a material which differs in kind from the material of said light-extracting surface.

7. The semiconductor light-emitting element according to claim 1, wherein at least one of said projected portions is provided with a flat apex.

8. The semiconductor light-emitting element according to claim 1, wherein at least one of said projected portions is provided with a flat apex, on which a very small transparent portion is disposed, said very small transparent portion being formed of a material differing in kind from the material of said light-extracting surface.

9. The semiconductor light-emitting element according to claim 2, wherein said substrate is provided, on said second surface, with a transparent oxide film or a transparent nitride film, and said finely recessed/projected portions are constituted by a surface of said transparent oxide film or of said transparent nitride film.

10. The semiconductor light-emitting element according to claim 4, wherein said current diffusion layer is disposed at the uppermost layer of said semiconductor laminate, and said finely recessed/projected portions exists on the exposed surface of said current diffusion layer.

11. The semiconductor light-emitting element according to claim 10, wherein said current diffusion layer is provided, on the exposed surface thereof, with a transparent oxide film or a transparent nitride film, and said finely recessed/projected portions are formed on a surface of said transparent oxide film or of said transparent nitride film.

12. A method of manufacturing a semiconductor light-emitting element, comprising:

forming a semiconductor laminate on a first surface of a substrate having a first surface and a second surface, said semiconductor laminate containing a light-emitting layer and a current diffusion layer;

determining a light-extracting surface for extracting light from said light-emitting layer;

forming a polymer film comprising a diblock copolymer on said light-extracting surface;

subjecting said polymer film to an annealing treatment, thereby phase-separating said diblock copolymer into two phases;

eliminating one of the phases of the diblock copolymer that has been phase-separated to form a mask material layer having a pattern constituted by the other phase; and

transferring said pattern of the mask material layer to said light-extracting surface to form finely recessed/projected portions on said light-extracting surface.

13. The method according to claim 12, wherein said polymer film is formed on the outermost surface of said semiconductor laminate.

14. The method according to claim 12, wherein said polymer film is formed on said second surface of said substrate.

15. The method according to claim 14, wherein said substrate is formed of a transparent substrate.

16. The method according to claim 12 further comprising:

forming a transparent film on said light-extracting surface prior to the formation of said polymer film on said light-extracting surface, said transparent film being made of an oxide or a nitride;

wherein said light-extracting surface is constituted by the surface of said transparent film.

17. The method according to claim 12, wherein said diblock copolymer contains an aromatic ring-containing polymer chain and an acrylic polymer chain.

18. The method according to claim 17, wherein said aromatic ring-containing polymer chain includes polystyrene, and said acrylic polymer chain includes poly(methyl methacrylate), wherein said diblock copolymer is phase-separated into polystyrene and poly(methyl methacrylate) by said annealing treatment, and said mask material layer is formed by eliminating said poly(methyl methacrylate), thereby leaving behind a pattern of said polystyrene.

19. The method according to claim 18, wherein said elimination of said poly(methyl methacrylate) is performed by etching said polymer layer containing said diblock copolymer which has undergone said phase separation.

20. The method according to claim 18, wherein said elimination of said poly(methyl methacrylate) is performed by applying irradiation of an electron beam, a development treatment and a rinsing treatment to said polymer layer containing said diblock copolymer which has undergone said phase separation.

21. The method according to claim 12, wherein said diblock copolymer includes an aromatic ring-containing polymer chain and an aliphatic double-bond polymer chain.

22. The method according to claim 20, wherein said aromatic ring-containing polymer chain includes polystyrene, and said aliphatic double-bond polymer chain includes polyisoprene, wherein said diblock copolymer is phase-separated into polystyrene and polyisoprene by said annealing treatment, and said mask material layer is formed by eliminating said polyisoprene to leave behind a pattern of said polystyrene by an ozone treatment.

23. The method according to claim 12, wherein said transferring of said pattern of the mask material layer to said light-extracting surface is performed by dry etching employing an RIE or by wet etching.