Light emitting device with small size and large density

• US 20200135704A1
• Filed: 12/24/2019
• Published: 04/30/2020
• Est. Priority Date: 05/20/2018
• Status: Active Grant

• Current Assignee: Black Peak LLC (Black Peak Holdings Pty Ltd.)
• Original Assignee: Black Peak LLC (Black Peak Holdings Pty Ltd.)
• Inventors: Herner, Scott Brad
• Granted Patent: US 10,727,210 B2
• Time in Patent Office: Days
• CPC Class Codes: H01L 21/28518 the conductive layers comprising silicides H01L21/28537 takes precedence
• CPC Class Codes: H01L 21/76898 formed through a semiconductor substrate
• CPC Class Codes: H01L 21/823475 interconnection or wiring or contact manufacturing related aspects
• CPC Class Codes: H01L 23/481 Internal lead connections, e.g. via connections, feedthrough structures
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• CPC Class Codes: H01L 27/0688 Integrated circuits having a three-dimensional layout
• CPC Class Codes: H01L 27/088 the components being field-effect transistors with insulated gate
• CPC Class Codes: H01L 29/45 Ohmic electrodes
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 2933/0058 relating to optical field-shaping elements
• CPC Class Codes: H01L 2933/0066 relating to arrangements for conducting electric current to or from the semiconductor body
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• 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 33/30 containing only elements of Group III and Group V of the Periodic Table
• CPC Class Codes: H01L 33/32 containing nitrogen
• CPC Class Codes: H01L 33/42 Transparent materials
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body
• 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

This application describes a light emitting device, an assembly of light emitting devices, a display comprising assemblies of light emitting devices, and methods of fabricating same. The light emitting device comprises a transistor, an LED that at least partially overlies the transistor, a reflector layer disposed between the LED and transistor, and conductive wires that connect electrically the transistor to the LED. The assembly comprises a plurality of light emitting devices, and the display comprises a plurality of assemblies.

Claims

1. A method for forming an assembly of light emitting devices, the method comprising:

providing a transistor substrate having a top surface and a bottom surface, the top surface comprising a plurality of conductive regions;

forming a plurality of transistors in the top surface of the transistor substrate;

providing an LED substrate;

forming a plurality of LEDs on the LED substrate, each LED of the plurality of LEDs having a surface area and wherein the plurality of LEDs comprises gallium nitride, indium gallium nitride, indium arsenide, aluminum gallium arsenide, gallium arsenide, gallium phosphide, gallium arsenide phosphide, or aluminum indium gallium phosphide;

forming at least one reflector layer, the at least one reflector layer at least partially overlying an LED of the plurality of LEDs;

bonding the plurality of transistors to the plurality of LEDs, wherein after bonding the plurality of transistors to the plurality of LEDs,

the at least one reflector layer is disposed between an LED of the plurality of LEDs and a transistor of the plurality of transistors,

each LED of the plurality of LEDs is connected electrically to a transistor of the plurality of transistors, and

each LED of the plurality of LEDs at least partially overlies a transistor of the plurality of transistors;

removing a thickness of the transistor substrate; and

forming a plurality of conductive wires, wherein each conductive wire of the plurality extends through the transistor substrate from conductive region of the plurality of conductive regions to the bottom surface of the transistor substrate.

2. The method of claim 1, wherein the transistor substrate comprises single crystal silicon.

3. The method of claim 1, wherein the transistor substrate comprises an etch-stop layer.

4. The method of claim 1, further comprising forming a plurality of interconnects, each interconnect extending from an LED of the plurality of LEDs.

5. The method of claim 1, further comprising providing a plurality of side reflectors, wherein the side reflectors are disposed between LEDs of adjacent light emitting devices of the plurality of light emitting devices and prevent light from adjacent light emitting devices from mutually interfering.

6. The method of claim 1, wherein after the step of removing a thickness of the transistor substrate step, the transistor substrate has a thickness less than 20 microns.

7. The method of claim 1, further comprising providing a backboard, wherein the backboard comprises a plurality of metal interconnects.

8. The method of claim 7, further comprising bonding each conductive wire of the plurality of conductive wires to one of the plurality of metal interconnects.

9. The method of claim 8, further comprising removing the LED substrate.

10. The method of claim 9, further comprising providing a plurality of wavelength-converting layers, wherein each wavelength-converting layer at least partially overlies an LED of the plurality of LEDs.

12. The method of claim 1, wherein the surface area of at least one LED of the plurality of LEDs is 40,000 square microns or less.

13. The method of claim 1, wherein the surface area of at least one LED of the plurality of LEDs is 1,000 square microns or less.

14. The method of claim 1, wherein the surface area of at least one LED of the plurality of LEDs is 100 square microns or less.