High density pixelated LED and devices and methods thereof

• US 10,312,224 B2
• Filed: 01/09/2017
• Issued: 06/04/2019
• 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:
  US15/401,240
• Publication Number:
  US 20170294418A1
• Time in Patent Office: 876 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 arranged to transmit LED emissions through a plurality of light-transmissive portions of a substrate, wherein the array of LEDs comprises at least one anode-cathode pair;

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, the plurality of light segregation elements is configured to reduce passage of LED emissions between the different light-transmissive portions, and the plurality of light-transmissive portions is configured to be illuminated by the array of LEDs to define a plurality of pixels that includes a plurality of border portions, wherein each pixel of the plurality of pixels includes at least one border portion of the plurality of border portions;

a plurality of inter-pixel light spreading regions configured to transmit light through border portions of the plurality of border portions to enhance inter-pixel illumination at light-emitting surface portions of the multi-LED chip that are registered with or proximate to the plurality of light segregation elements; and

at least one lumiphoric material arranged over the plurality of inter-pixel light spreading regions;

wherein the substrate is arranged between the array of LEDs and the at least one lumiphoric material; and

wherein the array of LEDs is arranged between the substrate and the at least one anode-cathode pair.

2. The multi-LED chip of claim 1, wherein the plurality of light segregation elements comprises at least one light-affecting material, and the plurality of inter-pixel light spreading regions comprises at least one light-transmissive material arranged in contact with the at least one light-affecting material.

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

the plurality of light segregation elements is arranged entirely within the substrate; and

the plurality of inter-pixel light spreading regions includes at least one light-transmissive material arranged at least partially within the substrate and over the plurality of light segregation elements.

4. The multi-LED chip of claim 1, wherein the plurality of inter-pixel light spreading regions comprises at least one light-transmissive material region that is elevated relative to a surface of the substrate and that is at least partially registered with the plurality of light segregation elements.

5. The multi-LED chip of claim 1, wherein the plurality of light segregation elements comprises a plurality of unfilled voids within portions of the substrate.

6. The multi-LED chip of claim 1, wherein the at least one lumiphoric material is 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.

7. The multi-LED chip of claim 1, wherein each light-transmissive portion of the plurality of light-transmissive portions of the substrate is separated from at least one other light-transmissive portion of the plurality of light-transmissive portions of the substrate by a gap that:

(i) has a width and a depth, (ii) is partially filled with a light segregation element of the plurality of light segregation elements, and (iii) is partially filled with at least one light-transmissive material defining an inter-pixel light spreading region of the plurality of inter-pixel light spreading regions.

8. The multi-LED chip of claim 7, wherein the gap includes a first portion of the width that is filled with the light segregation element, and includes a second portion of the width that is filled with the at least one light-transmissive material.

9. The multi-LED chip of claim 7, wherein the gap includes a first portion of the depth that is filled with the light segregation element, and includes a second portion of the depth that is filled with the at least one light-transmissive material.

10. The multi-LED chip of claim 7, further comprising at least one light-transmissive material region that is elevated relative to a surface of the substrate and that is at least partially registered with at least one of the light segregation element or the inter-pixel light spreading region.

11. The multi-LED chip of claim 1, wherein each light-transmissive portion of the plurality of light-transmissive portions of the substrate comprises at least one beveled edge forming an inter-pixel light spreading region of the plurality of inter-pixel light spreading regions.

12. The multi-LED chip of claim 11, wherein the substrate includes at least one light extraction surface including the at least one beveled edge, and the at least one lumiphoric material arranged on or over the at least one light extraction surface, wherein the at least one lumiphoric material is configured to receive at least a portion of the LED emissions and responsively generate lumiphor emissions.

13. The multi-LED chip of claim 1, further comprising:

a light-transmissive secondary substrate arranged over the substrate, wherein the at least one lumiphoric material is arranged between the light-transmissive secondary substrate and the substrate, and the at least one lumiphoric material is configured to receive at least a portion of the LED emissions and responsively generate lumiphor emissions.

14. The multi-LED chip of claim 13, further comprising a light scattering layer arranged on the light-transmissive secondary substrate.

15. The multi-LED chip of claim 13, wherein the plurality of inter-pixel light spreading regions is arranged at least partially within the light-transmissive secondary substrate.

16. The multi-LED chip of claim 13, wherein the plurality of inter-pixel light spreading regions comprises a plurality of light redirecting regions within the light-transmissive secondary substrate.

17. The multi-LED chip of claim 16, wherein the plurality of light redirecting regions comprises a plurality of voids defined within the light-transmissive secondary substrate.

18. The multi-LED chip of claim 16, wherein each light redirecting region of the plurality of light redirecting regions comprises a further light-transmissive material that differs in composition from a material of the light-transmissive secondary substrate.

19. A multi-LED chip comprising:

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

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, the plurality of light segregation elements is configured to reduce passage of LED emissions between the different light-transmissive portions;

a light-transmissive secondary substrate arranged over the substrate;

a lumiphoric material arranged between the light-transmissive secondary substrate and the substrate, wherein the lumiphoric material is configured to receive at least a portion of the LED emissions and responsively generate lumiphor emissions; and

a plurality of light redirecting regions arranged at least partially within the light-transmissive secondary substrate, wherein each light redirecting region of the plurality of light redirecting regions is configured to enhance illumination of light emitting surface portions of the multi-LED chip that are overlying and registered with the plurality of light segregation elements.

20. The multi-LED chip of claim 19, further comprising a light scattering layer arranged on the light-transmissive secondary substrate.

21. The multi-LED chip of claim 20, wherein the light-transmissive secondary substrate is arranged between the lumiphoric material and the light scattering layer.

22. The multi-LED chip of claim 19, wherein a portion of each light redirecting region extends into or through a lumiphoric material layer containing the lumiphoric material.

23. The multi-LED chip of claim 19, wherein the plurality of light redirecting regions comprises a plurality of voids defined within the light-transmissive secondary substrate.

24. The multi-LED chip of claim 19, wherein each light redirecting region of the plurality of light redirecting regions comprises a further light-transmissive material that differs in composition from a material of the light-transmissive secondary substrate.

25. The multi-LED chip of claim 19, wherein the plurality of light segregation elements comprises a plurality of unfilled voids defined in the substrate.

26. 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 that define a plurality of pixels, wherein each LED of the array of LEDs comprises a substrate material portion arranged over the active region;

a plurality of light segregation elements arranged between different 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, wherein the plurality of light segregation elements is configured to reduce passage of LED emissions between the different pixels;

a plurality of border portions, wherein each pixel of the plurality of pixels includes at least one border portion of the plurality of border portions;

a plurality of inter-pixel light spreading regions configured to transmit light through border portions of the plurality of border portions to enhance inter-pixel illumination at light-emitting surface portions of the multi-LED chip that are registered with or proximate to the plurality of light segregation elements;

at least one lumiphoric material arranged over the plurality of inter-pixel light spreading regions; and

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

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

27. The multi-LED chip of claim 26, wherein the array of LEDs is configured to transmit LED emissions through the substrate material portions, the array of LEDs comprises at least one anode-cathode pair, each substrate material portions is arranged between the functional stack and the at least one lumiphoric material, and the functional stack is arranged between the substrate material portions and at least one anode-cathode pair.

28. The multi-LED chip of claim 26, wherein the plurality of light segregation elements comprises a plurality of unfilled voids.