Fabrication method of light emitting diode incorporating substrate surface treatment by laser and light emitting diode fabricated thereby

• US 20060038190A1
• Filed: 09/30/2004
• Published: 02/23/2006
• Est. Priority Date: 08/17/2004
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electro-Mechanics Co., Ltd. (Samsung Group)
• Inventors: Hahm, Hun Joo, Park, Young Ho, Ko, Kun Yoo, Cho, Hyo Kyoung
• Granted Patent: US 7,160,744 B2
• Time in Patent Office: Days
• US Class Current: 257/95
• CPC Class Codes: H01L 21/02378 Silicon carbide
• CPC Class Codes: H01L 21/02403 Oxides
• CPC Class Codes: H01L 21/0242 Crystalline insulating materials
• CPC Class Codes: H01L 21/0243 Surface structure
• CPC Class Codes: H01L 21/02458 Nitrides
• CPC Class Codes: H01L 21/0254 Nitrides
• 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: Y10S 438/964 Roughened surface

Abstract

The present invention relates to a fabrication method of LEDs incorporating a step of surface-treating a substrate by a laser and an LED fabricated by such a fabrication method. The present invention can use a laser in order to implement finer surface treatment to an LED substrate over the prior art. As a result, the invention can improve the light extraction efficiency of an LED while protecting the substrate from chronic problems of the prior art such as stress or defects induced from chemical etching and/or physical polishing.

Claims

1. A fabrication method of Light Emitting Diodes (LEDs) comprising the following steps of:

(a) preparing a sapphire substrate;

(b) emitting a laser beam onto a first side of the sapphire substrate to form a fine roughened structure;

(c) forming an n-doped semiconductor layer, an active layer and a p-semiconductor layer in their order on the roughened side of the sapphire substrate;

(d) etching a resultant structure obtained in the step (c) into a mesa structure to expose a partial area of the n-doped semiconductor layer; and

(e) forming a p-electrode on the p-doped semiconductor layer and an n-electrode on the exposed area of the n-doped semiconductor layer.

2. The fabrication method of LEDs according to claim 1, further comprising the steps of:

(f) polishing a second side of the substrate to reduce the thickness of the substrate after the step (e); and

(g) emitting a laser beam onto the second side of the substrate to form a fine roughened structure therein.

3. The fabrication method of LEDs according to claim 1, the step (b) of forming a fine roughened structure comprises loading the substrate on a movable pedestal with the first side thereof facing upward, moving the movable pedestal at a predetermined rate, emitting the laser beam from a laser source, and opening a shutter on the path of the laser beam between the laser source and the substrate to form a groove at the movement of the pedestal to a predetermined pitch.

4. The fabrication method of LEDs according to claim 1, wherein the step (b) of forming a fine roughened structure comprises loading the substrate on a movable pedestal with the first side thereof facing upward, placing a mask having a number of holes matching the roughened structure above the substrate, and emitting the laser beam from a laser source above the mask onto the substrate so that the laser beam illuminates the first side of the substrate through the holes of the mask.

5. The fabrication method of LEDs according to claim 1, wherein the step (b) of forming a fine roughened structure comprises loading the substrate on a movable pedestal with the first side thereof facing upward, and moving the pedestal while emitting the laser beam onto the first side of the substrate, the laser beam having a diameter less than a groove in the roughened structure.

6. The fabrication method of LEDs according to claim 1, wherein the step (b) of forming a fine roughened structure comprises loading the substrate on a pedestal with the first side thereof facing upward and emitting the laser beam onto the first side of the substrate while moving a laser source, the laser beam having a diameter less than a groove formed in the roughened structure.

7. The fabrication method of LEDs according to claim 1, wherein the sapphire substrate is replaced by one selected from the group consisting of a SiC substrate, an oxide substrate and a carbide substrate.

8. A fabrication method of Light Emitting Diodes (LEDs) comprising the following steps of:

(a) preparing a sapphire substrate;

(b) forming a fine roughened structure in a first side of the sapphire substrate;

(c) forming an n-doped semiconductor layer, an active layer and a p-doped semiconductor layer in their order on the roughened sapphire substrate;

(d) etching a resultant structure obtained in the step (c) into a mesa structure to expose a partial area of the n-doped semiconductor layer;

(e) forming a p-electrode on the p-doped semiconductor layer and an n-electrode on the exposed area of the n-doped semiconductor layer;

(f) polishing a second side of the substrate to reduce the thickness of the substrate; and

(g) illuminating a laser beam onto the second side of the substrate to form a fine roughened structure therein.

9. The fabrication method of LEDs according to claim 8, wherein the step (b) comprises illuminating a laser beam onto the first side of the substrate to form the fine roughened structure therein.

10. The fabrication method of LEDs according to claim 8, the step (b) of forming a fine roughened structure comprises loading the substrate on a movable pedestal with the first side thereof facing upward, moving the movable pedestal at a predetermined rate, emitting the laser beam from a laser source, and opening a shutter on the path of the laser beam between the laser source and the substrate to form a groove at the movement of the pedestal to a predetermined pitch.

11. The fabrication method of LEDs according to claim 8, wherein the step (b) of forming a fine roughened structure comprises loading the substrate on a movable pedestal with the first side thereof facing upward, placing a mask having a number of holes matching the roughened structure above the substrate, and emitting the laser beam from a laser source above the mask onto the substrate so that the laser beam illuminates the first side of the substrate through the holes of the mask.

12. The fabrication method of LEDs according to claim 8, wherein the step (b) of forming a fine roughened structure comprises loading the substrate on a movable pedestal with the first side thereof facing upward, and moving the pedestal while emitting the laser beam onto the first side of the substrate, the laser beam having a diameter less than a groove in the roughened structure.

13. The fabrication method of LEDs according to claim 8, wherein the step (b) of forming a fine roughened structure comprises loading the substrate on a pedestal with the first side thereof facing upward and emitting the laser beam onto the first side of the substrate while moving a laser source, the laser beam having a diameter less than a groove formed in the roughened structure.

14. The fabrication method of LEDs according to claim 8, wherein the sapphire substrate is replaced by one selected from the group consisting of a SiC substrate, an oxide substrate and a carbide substrate.

15. A Light Emitting Diode (LED) comprising:

a sapphire substrate having a fine roughened structure formed in a first side thereof, the fine roughened structure being formed via laser illumination;

an n-doped semiconductor layer formed on the roughened first side of the substrate;

an active layer and a p-doped semiconductor layer formed in their order on the n-doped semiconductor layer to expose a partial area of the n-doped semiconductor layer;

a p-electrode formed on the p-doped semiconductor layer; and

an n-electrode formed on the exposed area of the n-doped semiconductor layer.

16. The LED diode according to claim 15, wherein the sapphire substrate has a second side polished to reduce the thickness of the sapphire substrate and a fine roughened structure formed in a second side via laser illumination.

17. The LED diode according to claim 15, wherein the sapphire substrate is replaced by one selected from the group consisting of a SiC substrate, an oxide substrate and a carbide substrate.

18. A Light Emitting Diode (LED) comprising:

a sapphire substrate having a first side having a fine roughened structure formed therein and a second side having a fine roughened structure formed therein via laser illumination;

an n-doped semiconductor layer formed on the roughened first side of the sapphire substrate;

an active layer and a p-doped semiconductor layer formed in their order on the n-doped semiconductor layer to expose a partial area of the n-doped semiconductor layer;

a p-electrode formed on the p-electrode layer; and

an n-electrode formed on the exposed area of the n-doped semiconductor layer.

19. The LED diode according to claim 18, wherein the fine roughened structure in the first side of the substrate is formed via laser illumination.

20. The LED diode according to claim 18, wherein the sapphire substrate is replaced by one selected from the group consisting of a SiC substrate, an oxide substrate and a carbide substrate.