Nitride semiconductor light emitting device and method of manufacturing the same

• US 20050221521A1
• Filed: 11/09/2004
• Published: 10/06/2005
• Est. Priority Date: 03/30/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electro-Mechanics Co., Ltd. (Samsung Group)
• Inventors: Lee, Jeong Wook, Lee, Jae Hoon, Kim, Hyun Kyung, Kim, Yong Chun
• Granted Patent: US 7,470,938 B2
• Time in Patent Office: Days
• US Class Current: 438/29
• CPC Class Codes: H01L 33/007 comprising nitride compounds
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: Y10S 257/918 Light emitting regenerative switching device, e.g. light emitting scr arrays, circuitry

Abstract

Disclosed herein is a nitride semiconductor light emitting device having patterns formed on the upper and lower surfaces of a substrate from which light is emitted in a flip chip bonding structure wherein the patterns are capable of changing light inclination at the upper and lower surfaces of the substrate to decrease total reflection at the interfaces, thereby improving light emitting efficiency. The nitride semiconductor light emitting device comprises a substrate having upper and lower surfaces on which predetermined patterns are formed such that light can be incident within a critical angle, the substrate allowing a gallium nitride-based semiconductor material to be grown thereon, an n-type nitride semiconductor layer formed on the upper surface of the substrate, an active layer formed on the upper surface of the n-type nitride semiconductor layer such that the n-type nitride semiconductor layer is partially exposed, a p-type nitride semiconductor layer formed on the upper surface of the active layer, a p-electrode formed on the upper surface of the p-type nitride semiconductor layer, and an n-side electrode formed on the partially exposed n-type nitride semiconductor layer.

Claims

1. A nitride semiconductor light emitting device comprising:

a substrate having upper and lower surfaces on which predetermined patterns are formed such that light can be incident within a critical angle, the substrate allowing a gallium nitride-based semiconductor material to be grown thereon;

an n-type nitride semiconductor layer formed on the upper surface of the substrate;

an active layer formed on the upper surface of the n-type nitride semiconductor layer such that the n-type nitride semiconductor layer is partially exposed;

a p-type nitride semiconductor layer formed on the upper surface of the active layer;

a p-electrode formed on the upper surface of the p-type nitride semiconductor layer; and

an n-side electrode formed on the partially exposed n-type nitride semiconductor layer.

2. The device as set forth in claim 1, wherein the nitride semiconductor light emitting device is a flip chip-type nitride semiconductor light emitting device constructed such that the p-bonding electrode and the n-side electrode are directly bonded to a circuit board and light is emitted through the substrate.

3. The device as set forth in claim 1, wherein the substrate is made of sapphire, SiC, or GaN.

4. The device as set forth in claim 1, wherein the substrate has a hemispherical convex pattern formed on a first surface thereof where the n-type nitride semiconductor layer is formed and a hemispherical concave pattern formed on a second surface thereof, the second surface of the substrate being opposite to the first surface of the substrate.

5. The device as set forth in claim 1, wherein the substrate has a first surface where the n-type nitride semiconductor layer is formed and a hemispherical convex pattern formed on a second surface thereof, the second surface of the substrate being opposite to the first surface of the substrate.

6. The device as set forth in claim 1, wherein the substrate has a hemispherical convex pattern formed on a first surface thereof where the n-type nitride semiconductor layer is formed and a prism-shaped convex pattern having triangle sections formed on a second surface thereof, the second surface of the substrate being opposite to the first surface of the substrate.

7. A method of manufacturing a nitride semiconductor light emitting device, the method comprising the steps of:

forming a predetermined pattern on a first surface of a substrate, the substrate also having a second surface;

forming a light emitting structure comprising an n-type nitride semiconductor layer, an active layer, and a p-type nitride semiconductor layer on the first surface of the substrate, the n-type nitride semiconductor layer, the active layer, and the p-type nitride semiconductor layer being disposed in sequence on the first surface of the substrate;

forming an N-electrode and a P-electrode on the n-type nitride semiconductor layer and the p-type nitride semiconductor layer of the light emitting structure, respectively;

grinding the second surface of the substrate;

attaching the N-electrode and the P-electrode to a jig substrate to make the substrate level;

forming another predetermined pattern on the second surface of the ground substrate; and

removing the jig substrate.

8. The method as set forth in claim 7, wherein the patterns formed on the first and second surfaces of the substrate are hemispherical concave and/or convex patterns.

9. The method as set forth in claim 7, wherein the pattern formed on the first surface of the substrate is a hemispherical concave and/or convex pattern, and the pattern formed on the second surface of the substrate is a prism-shaped convex pattern.

10. The method as set forth in claim 7 wherein, when the patterns are hemispherical convex patterns, the step of forming the patterns on the first and second surfaces of the substrate comprises the sub-steps of:

applying a photoresist having a predetermined thickness to the corresponding surface of the substrate;

removing the photoresist from the substrate, excluding the photoresist disposed at the positions where a plurality of convex parts of the hemispherical convex pattern are to be formed, to form a photoresist pattern;

re-flowing the substrate at a temperature of 100 to 150°

C. for approximately 1 to 5 minutes to form the photoresist pattern into hemispherical shapes; and

etching the corresponding surface of the substrate by means of inductively coupled plasma reactive ion etching (ICP-RIE) using the hemispherical photoresist as a mask to form a hemispherical convex pattern.

11. The method as set forth in claim 7, wherein, when the patterns are hemispherical concave patterns, the step of forming the patterns on the first and second surfaces of the substrate comprises the sub-steps of:

etching the substrate to form a first circular concave pattern having a plurality of concave parts arranged at regular intervals;

secondly etching the corresponding surface of the substrate to form a second circular concave pattern having a plurality of concave parts overlapping with the concave parts of the first circular concave pattern, respectively, each of the concave parts of the second circular concave pattern having a second diameter greater than the first diameter of each of concave parts of the first circular concave pattern; and

over-etching the first and second concave patterns to form a hemispherical concave pattern.

12. The method as set forth in claim 7, wherein the step of leveling the substrate comprises the sub-step of:

attaching the P-electrode and the N-electrode of the substrate to a jig substrate having a photoresist or polymer applied thereto;

performing hard baking on the substrate; and

leveling the substrate by means of the jig substrate.

13. The method as set forth in claim 12, wherein the jig substrate is a sapphire substrate or an Si substrate having a thickness different from that of the substrate.