LED UNITS FABRICATION METHOD

• US 20110159615A1
• Filed: 05/11/2010
• Published: 06/30/2011
• Est. Priority Date: 12/28/2009
• Status: Active Grant

• Current Assignee: Hon Hai Precision Industry Co., Ltd.
• Original Assignee: Hon Hai Precision Industry Co., Ltd.
• Inventors: LAI, CHIH-CHEN
• Granted Patent: US 8,030,102 B2
• Time in Patent Office: Days
• US Class Current: 438/29
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate

Abstract

A method for fabricating a plurality of individual light emitting diode units includes forming a GaN epitaxial layer on a sapphire substrate, forming a plurality of exhaust trenches on the GaN epitaxial layer, wherein the exhaust trenches define a plurality of individual light emitting diode units, forming a reflective layer on the GaN epitaxial layer, attaching the reflective layer to a conductive substrate, removing the sapphire substrate from the GaN epitaxial layer via a laser lift-off process, wherein a gas produced during the laser lift-off process is exhausted via the exhaust trenches, and dicing the conductive substrate along the exhaust trenches to form the plurality of individual light emitting diode units.

Claims

1. A method for fabricating a plurality of individual light emitting diode units, comprising:

providing a sapphire substrate;

forming a GaN epitaxial layer on the sapphire substrate;

forming a plurality of exhaust trenches on the GaN epitaxial layer, wherein the exhaust trenches define a plurality of individual light emitting diode units;

forming a reflective layer on the GaN epitaxial layer;

attaching the reflective layer to a conductive substrate;

removing the sapphire substrate from the GaN epitaxial layer via a laser lift-off process, wherein a gas produced during the laser lift-off process is exhausted via the exhaust trenches; and

dicing the conductive substrate along the exhaust trenches to form the plurality of individual light emitting diode units.

2. The method of claim 1, wherein formation of the GaN epitaxial layer comprises forming an n-GaN layer, an active layer, and a p-GaN layer on the sapphire substrate in that order via metal oxide chemical vapor deposition.

3. The method of claim 1, wherein formation of the reflective layer comprises depositing a reflective layer on the GaN epitaxial layer using plasma-enhanced chemical vapor deposition.

4. The method of claim 1, wherein formation of the exhaust trenches uses inductive couple plasma reactive ion etching.

5. The method of claim 1, wherein the exhaust trenches define a preserve region in a middle portion of the GaN epitaxial layer, and a sacrifice region in a marginal portion of the GaN epitaxial layer;

wherein the plurality of individual light emitting diode units is formed in the preserve region.

6. The method of claim 5, wherein the plurality of individual light emitting diode units has the same shape, and is arranged in rows along the exhaust trenches.

7. The method of claim 6, wherein a light spot projected on the GaN epitaxial layer by a laser beam has the same shape and size as an individual light emitting diode unit during the laser lift-off process.

8. The method of claim 7, wherein the laser lift-off process further comprises:

projecting an initial light spot on the sacrifice region adjacent to a first row of the individual light emitting diode units;

moving the initial light spot along the exhaust trench into the preserve region, and scanning each individual light emitting diode units of the row one by one;

stopping laser beam emission when the initial light spot passes through the preserve region;

projecting a new light spot on the sacrifice region adjacent to a second row of the individual light emitting diode units, the second row being adjacent to the first row; and

repeating movement of the initial light spot along the exhaust trench until each row of the individual light emitting diode units is scanned.

9. The method of claim 8, wherein the initial light spot entirely covers at least one individual light emitting diode unit during movement of the initial light spot.

10. The method of claim 8, wherein the initial light spot intercrosses a rim of the GaN epitaxial layer.