Semiconductor light emitting device and method for manufacturing the same

• US 7,741,649 B2
• Filed: 10/06/2008
• Issued: 06/22/2010
• Est. Priority Date: 09/10/2004
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Asakawa, Koji, Fujimoto, Akira, Ohashi, Kenichi
• Primary Examiner(s): Smith; Zandra
• Assistant Examiner(s): Patton; Paul E
• Application Number:
  US12/246,099
• Publication Number:
  US 20090042325A1
• Time in Patent Office: 624 Days
• Field of Search: 438/29, 438/32, 438/42, 438943-952, 257/12, 257/13, 257/79, 257/94, 257/95, 257/98, 257/E33.006, 372/43.01
• US Class Current: 257/95
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers

Abstract

In a semiconductor light emitting device, a semiconductor light emitting element has a light extracted surface on which a plurality of convex structures is formed. The convex structures each have a conical mesa portion constituting a refractive index gradient structure, a cylindrical portion constituting a diffraction grating structure, and a conical portion constituting a refractive index gradient structure. The mesa portion, cylindrical portion, and conical portion are arranged in this order from the light extracted surface. The period between the convex structures is longer than 1/(the refractive index of an external medium+the refractive index of the convex structures) of an emission wavelength and equal to or shorter than the emission wavelength. The circle-equivalent average diameter of the cylindrical portion is ⅓ to 9/10 of that of the bottom of the mesa portion.

Claims

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

forming a mask on which circular patterns are periodically arranged, on a light extracted surface of a semiconductor light emitting element,

selectively etching the light extracted surface of the semiconductor light emitting element by a reactive ion etching technique using the mask to form convex structures each including a conical mesa portion, a cylindrical portion, and a conical portion, the mesa portion, the cylindrical portion, and the conical portion being arranged in this order from the light extracted surface, a period between the convex structures being longer than 1/(a refractive index of an external medium+a refractive index of the convex structures) of an emission wavelength and equal to or shorter than the emission wavelength, and a circle-equivalent average diameter of the cylindrical portion being substantially constant from the mesa portion to the conical portion and being within a range of ⅓

to 9/10 of a circle-equivalent average diameter of a bottom of the mesa portion.

2. The method according to claim 1, wherein the light extracted surface is formed of a light radiation side outermost layer or an inorganic light transmission layer of the semiconductor light emitting element.

3. The method according to claim 1, wherein in order to form the mask, a resist is formed on the light extracted surface and the circular patterns are drawn on the resist by a lithography technique using electron light or light.

4. The method according to claim 1, wherein in order to form the mask, a thin film formed of a resin composition which contains a block copolymer or graft copolymer and which forms a micro phase separation structure in a self-organizing manner is formed on the light extracted surface and at least one of phases of the micro phase separation structure of the thin film is selectively removed.

5. The method according to claim 1, wherein in order to form the mask, polymer beads or silica beads configured in a monolayer are formed on the light extracted surface.

6. A method for manufacturing a semiconductor light emitting device comprising a semiconductor light emitting element, the method comprising:

forming a mask on which circular patterns are periodically configured, on a light extracted surface of a semiconductor light emitting element;

selectively etching the light extracted surface by a reactive ion etching technique using the mask to form a cylindrical portion of each of convex structures configuring a diffraction grating structure and setting a period between the convex structures longer than 1/(a refractive index of an external medium+a refractive index of the convex structures) of an emission wavelength and equal to or shorter than the emission wavelength; and

etching the light extracted surface by a physical etching technique using an inert gas to form a conical mesa portion at a bottom of each of the cylindrical portions, forming a conical portion at a top of the cylindrical portion, and setting a circle-equivalent average diameter of the cylindrical portion to be substantially constant from the mesa portion to the conical portion and to be within a range of ⅓

to 9/10 of a circle-equivalent average diameter of a bottom of the mesa portion.

7. The method according to claim 6, wherein the light extracted surface is formed of a light radiation side outermost layer or an inorganic light transmission layer of the semiconductor light emitting element.

8. The method according to claim 6, wherein in order to form the mask, a resist is formed on the light extracted surface and the circular patterns are drawn on the resist by a lithography technique using electron light or light.

9. The method according to claim 6, wherein in order to form the mask, a thin film formed of a resin composition which contains a block copolymer or graft copolymer and which forms a micro phase separation structure in a self-organizing manner is formed on the light extracted surface and at least one of phases of the micro phase separation structure of the thin film is selectively removed.

10. The method according to claim 6, wherein in order to form the mask, polymer beads or silica beads configured in a monolayer are formed on the light extracted surface.