Semiconductor light emitting device with protrusions to improve external efficiency and crystal growth

• US 8,119,534 B2
• Filed: 03/03/2010
• Issued: 02/21/2012
• Est. Priority Date: 08/19/2003
• Status: Active Grant

• Current Assignee: Nichia Corporation
• Original Assignee: Nichia Corporation
• Inventors: Tanaka, Hisanori, Hosokawa, Yasunobu, Shibutani, Yuuki
• Primary Examiner(s): Fahmy, Wael
• Assistant Examiner(s): Ingham, John C
• Application Number:
  US12/716,506
• Publication Number:
  US 20100197055A1
• Time in Patent Office: 720 Days
• Field of Search: 438/713, 438/734, 438/737, 438/29, 257/95, 257/E21.119
• US Class Current: 438/734
• CPC Class Codes: H01L 21/0237 Materials
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/0243 Surface structure
• CPC Class Codes: H01L 21/02433 Crystal orientation
• CPC Class Codes: H01L 21/0254 Nitrides
• CPC Class Codes: H01L 21/02647 Lateral overgrowth
• CPC Class Codes: H01L 21/02658 Pretreatments cleaning in general H01L21/02041
• CPC Class Codes: H01L 2224/48095 Kinked
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: H01L 2933/0083 Periodic patterns for optical field-shaping in or on the semiconductor body or semiconductor body package, e.g. photonic bandgap structures
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/22 : Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/38 : with a particular shape

Abstract

A substrate has at least one recess and/or protrusion formed in and/or on a surface thereof so as to scatter or diffract light generated in an active layer. The recess and/or protrusion is formed in such a shape that can reduce crystalline defects in semiconductor layers.

Claims

1. A method of manufacturing a substrate for a light emitting device that has a plurality of protrusions on a surface of the substrate where semiconductor layers of the light emitting device are formed, the method comprising:

a first step of preparing a substrate that is configured so that light from the light emitting device passes through the substrate and etching a part of the substrate with a protective film provided on the substrate and forming protrusions having side faces;

a second step of exposing and etching the side faces and at least a part of top faces of the protrusions so as to make an inclination angle of side faces on a lower side of the protrusions larger than an inclination angle of side faces on an upper side of the protrusions; and

a third step following the second step of exposing and etching the side faces and at least a part of the top faces of the protrusions so as to form the side faces into curved surfaces.

2. The method of manufacturing a substrate for the light emitting device according to claim 1, wherein the top faces of the protrusions are circular.

3. The method of manufacturing a substrate for the light emitting device according to claim 1, wherein the protective film is removed by the etching in the first step.

4. The method of manufacturing a substrate for the light emitting device according to claim 1, wherein a plurality of notches are formed on the side faces of the protrusions in the first step, and widths of notches in the side faces are larger on a lower side of the protrusions than widths of notches on an upper side of the protrusions or a number of notches is larger on a lower side of the protrusions than a number of notches on an upper side of the protrusions.

5. A method of manufacturing a substrate for a light emitting device that has a plurality of protrusions on a surface of the substrate where semiconductor layers of the light emitting device are formed, the method comprising:

a first step of preparing a substrate that is configured so that light from the light emitting device passes through the substrate and etching a part of the substrate with a protective film provided on the substrate and forming protrusions having side faces; and

a second step of exposing and etching the side faces and at least a part of top faces of the protrusions so as to make an inclination angle of side faces on a lower side of the protrusions larger than an inclination angle of side faces on an upper side of the protrusions and to make an inclination angle of side faces as a whole smaller than an inclination angle of side faces as a whole formed in the first step,

wherein the protective film is removed by the etching in the first step or the second step.

6. The method of manufacturing a substrate for the light emitting device according to claim 5, wherein, in the second step, an inclination angle θ

_m2 of the side faces as a whole is smaller than an inclination angle θ

_m1of the side faces as a whole formed in the first step.

7. The method of manufacturing a substrate for the light emitting device according to claim 5, wherein the protrusions have circular, triangular, parallelogram or hexagonal profiles.

8. The method of manufacturing a substrate for the light emitting device according to claim 5, further comprising:

a third step following the second step of exposing and etching the side faces and at least a part of the top faces of the protrusions so as to form the side faces into curved surfaces.

9. A method of manufacturing a substrate for a light emitting device that has a plurality of protrusions on a surface of the substrate where semiconductor layers of the light emitting device are formed, the method comprising:

a first step of preparing a substrate that is configured so that light from the light emitting device passes through the substrate and etching a part of the substrate with a protective film provided on the substrate and forming protrusions having side faces that have an inclination angle θ

_m1 as a whole; and

a second step of exposing and etching the side faces and at least a part of top faces of the protrusions so as to make an inclination angle θ

_m2 of the side faces as a whole smaller than the inclination angle θ

_m1,

wherein the protective film is removed by the etching in the first step or the second step and exposed protrusions are etched in the second step.

10. The method of manufacturing a substrate for the light emitting device according to claim 9, further comprising:

a third step following the second step of exposing and etching the side faces and at least a part of the top faces of the protrusions so as to make an inclination angle θ

_m3 of the side faces as a whole smaller than the inclination angle θ

_m2.

11. The method of manufacturing a substrate for the light emitting device according to claim 10, wherein, in the third step, the side faces are formed into curved surfaces.

12. The method of manufacturing a substrate for the light emitting device according to claims 9, wherein the protrusions have circular, triangular, parallelogram or hexagonal profiles.

13. The method of manufacturing a substrate for the light emitting device according to claim 12, wherein the substrate is a sapphire substrate having C plane (0001).

14. A method for manufacturing a light emitting device, wherein a nitride semiconductor structure of a light emitting device is formed on a protrusions-formed surface of a substrate manufactured by the method according to claim 13.