High-powered light emitting device with improved thermal properties

• US 7,351,599 B2
• Filed: 12/19/2005
• Issued: 04/01/2008
• Est. Priority Date: 02/19/2003
• Status: Expired due to Term

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Philips Lumileds Lighting Company LLC (Apollo Global Management, Inc.)
• Inventors: Martin, Paul S., Shen, Yu-Chen, Steigerwald, Daniel A.
• Primary Examiner(s): LINDSAY JR, WALTER LEE
• Application Number:
  US11/311,961
• Publication Number:
  US 20060097336A1
• Time in Patent Office: 834 Days
• Field of Search: 438/26, 438/27, 438/28, 438/34, 257/E21.053, 257/E21.358, 257/E21.352, 257/E21.36, 257/E21.361, 257/E21.362
• US Class Current: 438/26
• CPC Class Codes: H01L 2224/05001 Internal layers
• CPC Class Codes: H01L 2224/05023 the whole internal layer protruding from the surface
• CPC Class Codes: H01L 2224/05124 Aluminium [Al] as principal constituent
• CPC Class Codes: H01L 2224/05139 Silver [Ag] as principal constituent
• CPC Class Codes: H01L 2224/05144 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/05147 Copper [Cu] as principal constituent
• CPC Class Codes: H01L 2224/05568 the whole external layer protruding from the surface
• CPC Class Codes: H01L 2224/05599 Material
• CPC Class Codes: H01L 2224/0603 Bonding areas having different sizes, e.g. different heights or widths
• CPC Class Codes: H01L 2224/131 with a principal constituent of the material being a metal or a metalloid, e.g. boron [B], silicon [Si], germanium [Ge], arsenic [As], antimony [Sb], tellurium [Te] and polonium [Po], and alloys thereof
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 2224/16237 the bump connector connecting to a bonding area disposed in a recess of the surface of the item
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 24/16 of an individual bump connector
• CPC Class Codes: H01L 24/17 of a plurality of bump connectors
• 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 2924/01012 Magnesium [Mg]
• CPC Class Codes: H01L 2924/01019 Potassium [K]
• CPC Class Codes: H01L 2924/01029 Copper [Cu]
• CPC Class Codes: H01L 2924/01079 Gold [Au]
• CPC Class Codes: H01L 2924/014 : Solder alloys
• 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 33/38 : with a particular shape
• 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

A light emitting device includes a first semiconductor layer of a first conductivity type, an active region, and a second semiconductor layer of a second conductivity type. First and second contacts are connected to the first and second semiconductor layers. In some embodiments at least one of the first and second contacts has a thickness greater than 3.5 microns. In some embodiments, a first heat extraction layer is connected to one of the first and second contacts. In some embodiments, one of the first and second contacts is connected to a submount by a solder interconnect having a length greater than a width. In some embodiments, an underfill is disposed between a submount and one of the first and second interconnects.

Claims

1. A method of operating a light emitting device, the method comprising:

forming a first semiconductor layer of a first conductivity type;

forming an active region overlying the first semiconductor layer;

forming a second semiconductor layer of a second conductivity type overlying the active region;

selecting at least one of an area, thickness, and material of one of a first contact and a second contact to reduce a temperature gradient within the device during operation to less than about 30 K/mm;

forming the first contact electrically connected to the first semiconductor layer;

forming a second contact electrically connected to the second semiconductor layer; and

operating the device at a current density greater than 143 A/cm²;

wherein a maximum temperature gradient within the device is less than 30 K/mm during operation.

2. The method of claim 1 further comprising selecting at least one of an area, thickness, and material of one of a first contact and a second contact to reduce a thermal resistance per area of the device, defined as a change in temperature divided by a corresponding change in power and area, to below 10 K/W-mm².

3. The method of claim 1 further comprising forming at least one heat extraction layer electrically connected to one of the first contact and the second contact.

4. The method of claim 1 further comprising attaching one of the first contact and the second contact to a submount by a solder interconnect having a length longer than a width.

5. The method of claim 1 further comprising:

attaching one of the first contact and the second contact to a submount; and

providing an underfill in a space between the submount and one of the first contact and the second contact.