Microelectronic package having improved light extraction

• US 7,023,022 B2
• Filed: 11/14/2001
• Issued: 04/04/2006
• Est. Priority Date: 11/16/2000
• Status: Active Grant

• Current Assignee: Emcore Corporation
• Original Assignee: Emcore Corporation
• Inventors: Eliashevich, Ivan, Venugopalan, Hari, Karlicek, Robert F.
• Primary Examiner(s): Kang, Donghee
• Application Number:
  US10/416,996
• Publication Number:
  US 20040065886A1
• Time in Patent Office: 1,602 Days
• Field of Search: 257/81, 257/98, 257/100, 257/676, 257/680, 257/778, 438 22- 27, 313/501, 313/512
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• 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 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/46 Reflective coating, e.g. dielectric Bragg reflector

Abstract

A light-emitting package includes a substantially transparent substrate having a first surface and a second surface including a lens. The package also includes a light-emitting diode (LED) adapted to emit light having a predetermined wavelength, the LED being secured over the first surface of the substantially transparent substrate. The second surface of the substrate defines a principal light emitting surface of the package. The lens at the second surface has a grating pattern that matches the predetermined wavelength of the light emitted from the LED for controlling the emission geometry of the light emitted by the package. The grating pattern has a radial configuration including a series of circles that are concentric.

Claims

1. A light-emitting package comprising:

a substantially transparent substrate having a first surface and a second surface including a lens; and

a light-emitting diode (LED) adapted to emit light having a predetermined wavelength, said LED being secured over the first surface of said substantially transparent substrate, wherein the second surface of said substrate defines a principal light emitting surface of said package, and wherein said lens at said second surface has a grating pattern that matches the predetermined wavelength of the light emitted from said LED for controlling the emission geometry of the light emitted by said package, wherein the grating pattern has a radial configuration including a series of circles, and wherein the series of circles are concentric circles.

2. The package as claimed in claim 1, wherein said package is flip-chip mountable to a microelectronic element so that the second surface of said substantially transparent substrate overlies the LED of said package and so that the second surface of said substantially transparent substrate is remote from said microelectronic element.

3. The package as claimed in claim 1, wherein the lens is formed using a subtractive etching process that removes a portion of the second surface of said substantially transparent substrate.

4. The package as claimed in claim 1, wherein the lens is formed using an additive process that deposits material over the second surface of said substantially transparent substrate.

5. The package as claimed in claim 1, wherein the lens is a fresnel lens formed using a subtractive etching process.

6. The package as claimed in claim 1, wherein said light emitting diodes comprise materials selected from the group consisting of III–

V semiconductors.

7. The package as claimed in claim 1, wherein said substrate is selected from the group of materials consisting of sapphire, GaN, AlN, ZnO and LiGaO.

8. The package as claimed in claim 1, wherein said light emitting diode is a GaN light emitting diode and said substrate is made of sapphire.

9. A light emitting package comprising:

a substantially transparent substrate having a first surface and a second surface including a lens; and

a light emitting diode (LED) secured over the first surface of said substantially transparent substrate, wherein the second surface of said substrate defines a principal light emitting surface of said package, and wherein said lens includes a grating pattern having a radial configuration including a series of circles, and wherein the series of circles are concentric circles.

10. The package as claimed in claim 9, further comprising a substantially transparent encapsulant encapsulating at least a portion of said substantially transparent substrate.

11. A method of making a light emitting package comprising:

providing a substantially transparent substrate having a first surface and a second surface;

mounting a light emitting diode (LED) over the first surface of said substantially transparent substrate; and

forming a lens at the second surface of said substantially transparent substrate for optimizing light extraction from said package, wherein said lens has a grating pattern having a radial configuration including a series of circles, and wherein the series of circles are concentric circles.

12. The method as claimed in claim 11, further comprising flip-chip mounting said light emitting diode to a microelectronic element so that the lens at the second

surface of said substantially transparent substrate is remote from said microelectronic element.

13. The method as claimed in claim 11, wherein said microelectronic element is a circuitized substrate.

14. The method as claimed in claim 11, further comprising encapsulating said light emitting package with a substantially transparent encapsulant.

15. The method as claimed in claim 11, wherein said substantially transparent encapsulant is a material selected from the group consisting of epoxies, elastomers and polymers.

16. The method as claimed in claim 11, wherein said light emitting diode comprises materials selected from the group consisting of III–

V semiconductors.

17. The method as claimed in claim 11, wherein said substrate is selected from the group consisting of sapphire, GaN, AlN, ZnO and LiGaO.