Bonding of light emitting diodes having shaped substrates

• US 7,341,175 B2
• Filed: 04/27/2004
• Issued: 03/11/2008
• Est. Priority Date: 07/23/2001
• Status: Expired due to Term

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Andrews, Peter S., Negley, Gerald H., Slater, David B. Jr., Edmond, John, Raffetto, Mark, Bharathan, Jayesh, Mohammed, Anwar
• Primary Examiner(s): Stoner; Kiley
• Application Number:
  US10/832,971
• Publication Number:
  US 20040200882A1
• Time in Patent Office: 1,414 Days
• Field of Search: 228/110.1, 228/1.1, 257/79, 257/81, 257/86, 257/87, 257/99
• US Class Current: 228/110.1
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48463 the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 24/32 of an individual layer connector
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/12032 Schottky diode
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/40 Materials therefor
• CPC Class Codes: H01L 33/62 Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls

Abstract

Bonding of flip-chip mounted light emitting devices having an irregular configuration is provided. Light emitting diodes having a shaped substrate are bonded to a submount by applying forces to the substrate an a manner such that shear forces within the substrate do not exceed a failure threshold of the substrate. Bonding a light emitting diode to a submount may be provided by applying force to a surface of a substrate of the light emitting diode that is oblique to a direction of motion of the light emitting diode to thermosonically bond the light emitting diode to the submount. Collets for use in bonding shaped substrates to a submount and systems for bonding shaped substrates to a submount are also provided.

Claims

1. A method of thermosonically bonding a light emitting diode to a submount, the light emitting diode having a substrate, an active region on the substrate, and a metal pad on the active region opposite the substrate, the method comprising:

placing the metal pad of the light emitting diode in contact with the submount; and

applying force to a planar surface of a substrate of the light emitting diode that is oblique to a direction of thermosonic motion of the light emitting diode while the metal pad is in contact with the submount to thermosonically bond the light emitting diode to the submount.

2. The method of claim 1, wherein the step of applying force comprises:

mating a collet to the surface of the substrate oblique to the direction of motion; and

moving the collet in the direction of motion.

3. The method of claim 2, wherein mating a collet comprises seating a collet having a mating surface corresponding to an oblique surface of the substrate so that the mating surface of the collet contacts the oblique surface of the substrate.

4. The method of claim 3, wherein the mating surface of the collet is a fixed surface relative to a body of the collet.

6. The method of claim 3, wherein seating the collet comprises:

placing the collet over the light emitting diode; and

applying a vacuum pressure to the collet.

7. The method of claim 1, wherein the light emitting diode comprises a gallium nitride based light emitting diode having a silicon carbide shaped substrate.

8. The method of claim 7, wherein the silicon carbide shaped substrate has a cubic portion and a truncated pyramidal portion adjacent the cubic portion and wherein the step of applying force comprises applying force to sidewalls of the truncated pyramidal portion of the silicon carbide substrate.

9. The method of claim 1, wherein applying force comprises applying force through a collet to the surface of the substrate of the light emitting diode that is oblique to a direction of motion of the light emitting diode.

10. The method of claim 1, wherein applying force comprises applying force through the substrate toward the metal pad to bond the light emitting diode to the submount.

11. The method of claim 1, wherein applying force comprises applying vibrational force to thermosonically bond the light emitting diode to the submount.

5. A method of thermosonically bonding a light emitting diode to a submount, comprising:

applying force to a surface of a substrate of the light emitting diode that is oblique to a direction of motion of the light emitting diode to thermosonically bond the light emitting diode to the submount;

wherein the step of applying force comprises;

mating a collet to the surface of the substrate oblique to the direction of motion; and

moving the collet in the direction of motion;

wherein mating a collet comprises seating a collet having a mating surface corresponding to an oblique surface of the substrate so that the mating surface of the collet contacts the oblique surface of the substrate; and

wherein the mating surface of the collet is a moveable surface relative to a body of the collet.