High density pixelated LED and devices and methods thereof

• US 10,529,696 B2
• Filed: 01/05/2017
• Issued: 01/07/2020
• Est. Priority Date: 04/12/2016
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Edmond, John, Donofrio, Matthew, Reiherzer, Jesse, Andrews, Peter Scott, Clark, Joseph G., Haberern, Kevin
• Primary Examiner(s): Enad, Christine A
• Application Number:
  US15/399,729
• Publication Number:
  US 20170294417A1
• Time in Patent Office: 1,097 Days
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 25/50 Multistep manufacturing processes of assemblies consisting of devices, each device being of a type provided for in group H01L27/00 or H01L29/00 H01L21/50 takes precedence
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H01L 2933/0033 relating to semiconductor body packages
• CPC Class Codes: H01L 2933/0058 relating to optical field-shaping elements
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/382 the electrode extending partially in or entirely through the semiconductor body
• 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
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/508 having a non-uniform spatial arrangement or non-uniform concentration, e.g. patterned wavelength conversion layer, wavelength conversion layer with a concentration gradient of the wavelength conversion material
• CPC Class Codes: H01L 33/58 Optical field-shaping elements
• CPC Class Codes: H01L 33/60 Reflective elements
• 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

At least one array of LEDs (e.g., in a flip chip configuration) is supported by a substrate having a light extraction surface overlaid with at least one lumiphoric material. Light segregation elements registered with gaps between LEDs are configured to reduce interaction between emissions of different LEDs and/or lumiphoric material regions to reduce scattering and/or optical crosstalk, thereby preserving pixel-like resolution of the resulting emissions. Light segregation elements may be formed by mechanical sawing or etching to define grooves or recesses in a substrate, and filling the grooves or recesses with light-reflective or light-absorptive material. Light segregation elements external to a substrate may be defined by photolithographic patterning and etching of a sacrificial material, and/or by 3D printing.

Claims

1. A multi-LED chip comprising:

an array of LEDs supported by a substrate and arranged to transmit LED emissions through a plurality of light-transmissive portions of the substrate;

at least one lumiphoric material arranged on or over a light extraction surface of the substrate, wherein the at least one lumiphoric material is configured to receive at least a portion of the LED emissions and responsively generate lumiphor emissions, and wherein the at least one lumiphoric material comprises a plurality of light output areas substantially registered with the plurality of light-transmissive portions; and

a plurality of light segregation elements arranged at least partially within the substrate, wherein light segregation elements of the plurality of light segregation elements are arranged between different light-transmissive portions of the plurality of light-transmissive portions, and the plurality of light segregation elements is configured to reduce passage of LED emissions between the different light-transmissive portions;

wherein the multi-LED chip comprises at least one of the following features (i) or (ii);

(i) the substrate comprises a light injection surface that opposes the light extraction surface;

a first group of light segregation elements of the plurality of light segregation elements extends from the light injection surface into an interior of the substrate; and

a second group of light segregation elements of the plurality of light segregation elements extends from the light extraction surface into the interior of the substrate;

or

(ii) the plurality of light segregation elements includes internal portions extending from an interior of the substrate to the light extraction surface, and includes external portions extending beyond the light extraction surface.

2. The multi-LED chip of claim 1, wherein each LED of the array of LEDs is in a flip chip configuration.

3. The multi-LED chip of claim 1, wherein each LED of the array of LEDs comprises an anode-cathode pair, and wherein the anode-cathode pair for each LED of the array of LEDs is electrically isolated from the anode-cathode pair of each other LED of the array of LEDs.

4. The multi-LED chip of claim 3, wherein each LED of the array of LEDs comprises a front side and a back side that opposes the front side, the substrate of each LED is closer to the front side than to the back side, and the anode-cathode pair of each LED is arranged along the back side.

5. The multi-LED chip of claim 1, wherein:

the substrate comprises a light injection surface that opposes the light extraction surface;

a first group of light segregation elements of the plurality of light segregation elements extends from the light injection surface into an interior of the substrate; and

a second group of light segregation elements of the plurality of light segregation elements extends from the light extraction surface into the interior of the substrate.

6. The multi-LED chip of claim 1, wherein the plurality of light segregation elements includes internal portions extending from an interior of the substrate to the light extraction surface, and includes external portions extending beyond the light extraction surface.

7. The multi-LED chip of claim 6, further comprising a plurality of light extraction recesses bounded by the light extraction surface and the external portions of the plurality of light segregation elements, wherein the at least one lumiphoric material is arranged at least partially within the plurality of light extraction recesses.

8. The multi-LED chip of claim 6, wherein the external portions are discontinuous relative to the internal portions.

9. The multi-LED chip of claim 1, wherein the light extraction surface defines a plurality of light extraction recesses, and the at least one lumiphoric material is arranged at least partially within the plurality of light extraction recesses.

10. The multi-LED chip of claim 1, wherein the at least one lumiphoric material comprises a first lumiphoric material corresponding to a first light output area of the plurality of light output areas, and a second lumiphoric material corresponding to a second light output area of the plurality of light output areas.

11. The multi-LED chip of claim 1, wherein the plurality of light segregation elements comprises a light-reflective material.

12. The multi-LED chip of claim 1, wherein the plurality of light segregation elements is registered with boundaries between at least some LEDs of the array of LEDs.

13. The multi-LED chip of claim 1, wherein the substrate comprises a growth substrate over which active layers of the array of LEDs were grown.

14. A multi-LED chip comprising:

an array of LEDs;

at least one lumiphoric material, wherein the at least one lumiphoric material is configured to receive at least a portion of LED emissions and responsively generate lumiphor emissions, wherein the at least one lumiphoric material comprises a plurality of light output areas; and

a plurality of light segregation elements registered with boundaries between at least some LEDs of the array of LEDs;

wherein the at least one lumiphoric material overlaps a portion of each light segregation element of the plurality of light segregation elements; and

wherein a plurality of voids is defined in the at least one lumiphoric material, and each void of the plurality of voids is registered with a different light segregation element of the plurality of light segregation elements.

15. The multi-LED chip of claim 14, wherein each LED of the array of LEDs is in a flip chip configuration.

16. The multi-LED chip of claim 14, wherein a plurality of light extraction recesses are bounded by the plurality of light segregation elements and a light extraction surface of a light-transmissive substrate, and wherein the at least one lumiphoric material is arranged at least partially within the plurality of light extraction recesses.

17. The multi-LED chip of claim 14, wherein a light extraction surface of a light-transmissive substrate defines a plurality of light extraction recesses, and the at least one lumiphoric material is arranged at least partially within the plurality of light extraction recesses.

18. The multi-LED chip of claim 14, further comprising a light transmissive substrate, wherein portions of the plurality of light segregation elements extend into an interior of the substrate.

19. The multi-LED chip of claim 18, wherein the at least one lumiphoric material comprises a first lumiphoric material and a second lumiphoric material, the first lumiphoric material is arranged to cover a first portion of a light extraction surface of the light-transmissive substrate, and the second lumiphoric material is arranged to cover a second portion of the light extraction surface.

20. The multi-LED chip of claim 14, wherein each LED of the array of LEDs comprises an anode-cathode pair, and wherein the anode-cathode pair for each LED of the array of LEDs is electrically isolated from the anode-cathode pair of each other LED of the array of LEDs.

21. The multi-LED chip of claim 20, wherein each LED of the array of LEDs comprises a front side and a back side that opposes the front side, the substrate of each LED is closer to the front side than to the back side, and the anode-cathode pair of each LED is arranged along the back side.

22. The multi-LED chip of claim 14, wherein the plurality of light segregation elements comprises a light-reflective material.

23. A multi-LED chip comprising:

a functional stack comprising a plurality of semiconductor layers and an active region;

an array of LEDs formed in the functional stack and defining a plurality of pixels,

wherein each LED of the array of LEDs comprises a light-transmissive substrate material portion arranged over the active region;

a plurality of light segregation elements registered with boundaries between at least some pixels of the plurality of pixels, the plurality of light segregation elements comprising reflective material arranged between substrate material portions of different LEDs of the array of LEDs; and

an underfill material registered with boundaries between at least some pixels of the plurality of pixels;

wherein the underfill material extends continuously in a lateral direction between active regions of each LED of the array of LEDs; and

wherein the plurality of light segregation elements comprises at least one recess configured to expose the underfill material.

24. The multi-LED chip of claim 23, wherein the underfill material comprises a dielectric material.

25. The multi-LED chip of claim 23, wherein each substrate material portion is discontinuous from each other substrate material portion and is registered with a different pixel of plurality of pixels.

26. The multi-LED chip of claim 25, wherein the at least one recess extends through an entire thickness of substrate material portions of at least two adjacent LEDs of the array of LEDs.