LIGHT EMITTING DIODE WITH HIGH ASPECT RATIO SUBMICRON ROUGHNESS FOR LIGHT EXTRACTION AND METHODS OF FORMING

• US 20110169030A1
• Filed: 03/10/2011
• Published: 07/14/2011
• Est. Priority Date: 07/02/2004
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Li, Ting
• Granted Patent: US 8,507,924 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/13 of an individual bump connector
• CPC Class Codes: H01L 2924/00011 Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/10155 being other than a cuboid
• CPC Class Codes: H01L 2924/10158 at the passive surface
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers

Abstract

The surface morphology of an LED light emitting surface is changed by applying a reactive ion etch (RIE) process to the light emitting surface. High aspect ratio, submicron roughness is formed on the light emitting surface by transferring a thin film metal hard-mask having submicron patterns to the surface prior to applying a reactive ion etch process. The submicron patterns in the metal hard-mask can be formed using a low cost, commercially available nano-patterned template which is transferred to the surface with the mask. After subsequently binding the mask to the surface, the template is removed and the RIE process is applied for time duration sufficient to change the morphology of the surface. The modified surface contains non-symmetric, submicron structures having high aspect ratio which increase the efficiency of the device.

Claims

1. A method of fabricating a metal hard-mask comprising submicron patterns, the method comprising:

providing a nano-patterned template comprising at least one porous material, wherein the nano-pattern is an inherent property of the at least one material; and

depositing a thin layer of metal on the template.

2. The method of claim 1, wherein the thickness of the metal layer is less than about 200 nm.

3. The method of claim 1, wherein the template comprises at least one of an inorganic polymer and an organic polymer.

4. The method of claim 1, wherein the template comprises anodic aluminum oxide.

5. The method of claim 1, wherein the template further comprises at least one of a sacrificial layer and a mold release layer.

6. A light emitting diode, comprising:

a plurality of semiconductor layers at least one of which has a light emitting surface;

at least a portion of said light emitting surface having a high aspect ratio submicron roughness to enhance light extraction.

7. A semiconductor device, comprising:

a plurality of semiconductor layers at least one of which has an exposed surface;

at least a portion of said exposed surface having a high aspect ratio submicron roughness.