Laser patterning of light emitting devices

• US 7,419,912 B2
• Filed: 04/01/2004
• Issued: 09/02/2008
• Est. Priority Date: 04/01/2004
• Status: Active Grant

• Current Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Donofrio, Matthew
• Primary Examiner(s): Chambliss; Alonzo
• Application Number:
  US10/815,293
• Publication Number:
  US 20050227379A1
• Time in Patent Office: 1,615 Days
• Field of Search: None
• US Class Current: 438/694
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 2103/50 Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
• CPC Class Codes: B23K 2103/52 Ceramics
• CPC Class Codes: B23K 26/066 by using masks
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: Y10S 438/94 Laser ablative material removal

Abstract

Light extraction features are provided for a light emitting device having a substrate and a semiconductor light emitting element on the substrate by shaping a surface of a layer of semiconductor material utilizing a laser to define three dimensional patterns in the layer of semiconductor material. The layer of semiconductor material may be the substrate. In particular embodiments of the present invention, the surface of the layer of semiconductor material is shaped by applying laser light to the layer of semiconductor material at an energy sufficient to remove material from the layer of semiconductor material. The laser light may also by applied in a blanket manner at a level below the ablation threshold. The application of laser light to the layer of semiconductor material may be followed by etching the substrate. The layer of semiconductor material may be anisotropically etched. A mask could also be patterned utilizing laser light and the layer of semiconductor material etched using the mask. Light emitting devices have three dimensional patterns in a layer of semiconductor material of the device are also provided.

Claims

1. A method of shaping a surface of a silicon carbide substrate, comprising:

patterning a mask layer on the silicon carbide substrate using a laser to remove material from the mask layer, wherein patterning the mask layer comprises applying laser light to the mask layer at an energy sufficient to remove material from the mask layer while scanning a pattern into the mask layer to form three dimensional geometric patterns in the mask layer; and

etching the silicon carbide substrate using the patterned mask layer to define the three dimensional geometric patterns, wherein the three dimensional geometric patterns comprise a plurality of different geometric patterns.

2. The method of claim 1, wherein the mask is a polymer mask.

3. The method of claim 1, further comprising forming a light emitting element on the substrate.

4. The method of claim 1, wherein a shape of the three dimensional geometric patterns of the mask layer is based on a difference between an etch rate of the silicon carbide substrate and an etch rate of the mask layer.

5. The method of claim 1, further comprising forming a micro-mask between the mask layer and the silicon carbide substrate, the micro-mask being configured to roughen a surface of the substrate during the etching.

6. The method of claim 5, wherein the micro-mask comprises an aluminum layer between the mask layer and the substrate.

7. The method of claim 1, wherein the plurality of different geometric patterns are provided in a single etch and in a single patterning of the mask layer.

8. The method of claim 7, wherein the plurality of different geometric patterns comprise surfaces that are angled with respect to the surface of the silicon carbide substrate.

9. A method of shaping a surface of a silicon carbide substrate, comprising:

forming a mask layer on the surface of the silicon carbide substrate;

patterning the mask layer using a laser to remove material from the mask layer, wherein patterning the mask layer comprises scanning laser light onto the mask layer at an energy sufficient to remove material from the mask layer to form three-dimensional geometric features in the mask layer having sidewalls that are angled relative to the surface of the substrate; and

anisotropically etching the silicon carbide substrate using the patterned mask layer to define the three dimensional geometric patterns having sidewalls that are angled relative to the surface of the substrate.