# US 2019/0355708 A1 · Method for Fabricating a Hybrid Display using Inorganic Micro Light Emitting Diodes (uLEDs) and Organic LEDs (OLEDs)

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- Number: US 2019/0355708 A1
- Document ID: US20190355708A1
- Status: Published application
- Kind: A1
- Application number: 16/508,414
- Filed: 2019-07-11
- Published: 2019-11-21
- Earliest claimed: 2014-10-31
- Assignees: eLux, Inc.
- Applicants: eLux Inc.
- Inventors: Kenji Sasaki; Paul J. Schuele; Kurt Ulmer; Jong-Jan Lee
- Web page: https://patentgrep.com/patent/US20190355708A1

## CPC

- H10W 90/00: Package configurations
- G09G 3/006: {Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays (testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309)}
- H10K 59/35: comprising red-green-blue [RGB] subpixels
- H10K 59/70: OLEDs integrated with inorganic light-emitting elements, e.g. with inorganic electroluminescent elements
- H10W 72/00: Interconnections or connectors in packages
- H10H 20/036: {of packages}
- H10K 59/1201: {Manufacture or treatment}
- H10K 59/123: Connection of the pixel electrodes to the thin film transistors [TFT]
- H10W 70/09: extending onto an encapsulation that laterally surrounds the chip or wafer, e.g. fan-out wafer level package [FOWLP] RDLs
- H10W 70/099: {Connecting interconnections to insulating or insulated package substrates, interposers or redistribution layers}
- H10W 70/682: {comprising holes having chips therein}
- H10W 72/0198: {batch processes}
- H10W 72/07236: {Soldering or alloying}
- H10W 72/874: {On different surfaces}
- H10W 72/9413: {on encapsulations}
- H10W 72/944: {Dispositions of multiple bond pads}
- H10W 90/22: the stacked chips being on both top and bottom sides of a package substrate, interposer or RDL
- H10W 90/722: {between stacked chips}
- H10W 90/732: {between stacked chips}
- H10W 90/734: {between a chip and a stacked insulating package substrate, interposer or RDL}
- H10W 90/736: {between a chip and a stacked lead frame, conducting package substrate or heat sink}
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10H: INORGANIC LIGHT-EMITTING SEMICONDUCTOR DEVICES HAVING POTENTIAL BARRIERS

## Abstract

A hybrid light emitting diode (LED) display and fabrication method are provided. The method forms a stack of thin-film layers overlying a top surface of a substrate. The stack includes an LED control matrix and a plurality of pixels. Each pixel is made up of a first subpixel enabled using an inorganic micro LED (uLED), a second subpixel enabled using an organic LED (OLED), and a third subpixel enabled using an OLED. The first subpixel emits a blue color light, the second subpixel emits a red color light, and the third subpixel emits a green color light. In one aspect, the stack includes a plurality of wells in a top surface of the stack, populated by the LEDs. The uLEDs may be configured vertical structures with top and bottom electrical contacts, or surface mount top surface contacts. The uLEDs may also include posts for fluidic assembly orientation.

## Claims

### Claim at position 1

1-14. (canceled)

### Claim 15

A method for fabricating a hybrid light emitting diode (LED) emissive display, the method comprising:
providing a substrate;
forming a stack of thin-film layers overlying a top surface of the substrate, with a plurality of wells formed in a top surface of the thin film stack, and with adjacent wells separated by well sidewalls, the stack comprising an LED control matrix and a plurality of pixels populating the wells with LEDs;
wherein each pixel comprises:
a first subpixel enabled using an inorganic micro LED (uLED) populating a well;
a second subpixel enabled using an organic LED (OLED) populating a well;
a third subpixel enabled using an OLED populating a well; and,
the method further comprising:
forming an electrical interface matrix layer overlying the stack, connected to each OLED.

### Claim 16

(canceled)

### Claim 17 (depends on 15)

The method of claim 15 wherein the first subpixel emits a blue color light;
wherein the second subpixel emits a red color light; and,
wherein the third subpixel emits a green color light.

### Claim 18 (depends on 15)

The method of claim 15 wherein the uLEDs are gallium nitride (GaN) LEDs.

### Claim 19 (depends on 15)

The method of claim 15 wherein the uLEDs are configured with an electrical connection interface selected from the group consisting of vertical structure contacts and surface mount top surface contacts.

### Claim 20 (depends on 15)

The method of claim 15 wherein each uLED includes a post.

### Claim 21 (depends on 15)

The method of claim 15 wherein the LED control matrix is an active matrix (AM) of control circuits, each control circuit electrically connected to a corresponding LED.

### Claim 22 (depends on 15)

The method of claim 15 wherein forming the stack of thin films includes
forming a light blocking material over the well sidewalls.

### Claim 23 (depends on 22)

The method of claim 22 wherein the light blocking material is selected from the group consisting of a light absorbing material and a light reflector material.

### Claim 24 (depends on 15)

The method of claim 15 wherein forming the stack of thin films includes:
forming each uLED well comprising a bottom surface, sidewalls, a first electrical interface formed on the uLED bottom surface and connected to the LED control matrix, and a second electrical interface formed on the uLED well bottom surface and connected to a reference voltage;
fluidically depositing surface mount uLEDs into the uLED wells, where each surface mount uLED comprising;
a top surface deposited overlying a corresponding uLED well bottom surface;
a bottom surface;
a first electrical contact formed on the uLED top surface; and,
a second electrical contact formed on the uLED top surface; and,
annealing the substrate to electrically connect each uLED first electrical contact to a corresponding uLED well first electrical interface, and to electrically connect each uLED second electrical contact to a corresponding uLED well second electrical interface.

### Claim 25 (depends on 24)

The method of claim 24 wherein forming the stack of thin films includes:
forming each OLED well comprising a bottom surface, sidewalls, and a first electrode formed on the OLED well bottom surface and connected to the LED control matrix;
forming an OLED heterostructure overlying the first electrode in each OLED well; and,
wherein forming the electrical interface matrix layer includes forming a second electrode overlying each OLED heterostructure, connected to a reference voltage.

### Claim 26 (depends on 25)

The method of claim 25 wherein the OLED heterostructures are formed subsequent to annealing the substrate.

### Claim 27 (depends on 24)

The method of claim 24 wherein fluidically depositing the surface mount uLEDs includes each surface mount uLED comprising:
the first electrical contact configured as a ring with a first diameter;
the second electrical contact formed within a first electrical contact ring perimeter;
wherein forming the uLED wells includes:
forming each uLED well first electrical interface as a partial ring with the first diameter, and having a mouth opening; and,
forming each uLED well second electrical interface as a trace extending into the mouth of a corresponding first electrical interface partial ring.

### Claim 28 (depends on 24)

The method of claim 24 wherein fluidically depositing the surface mount uLEDs includes each surface mount uLED top surface being bi-planar with a first level and a second level, and comprising:
the first electrical contact being formed on the first level of the top surface;
the second electrical contact being formed on the second level of the top surface;
wherein forming the uLED wells includes forming bi-planar uLED well bottom surfaces, with a first level and a second level, and including:
forming each first electrical interface on the uLED well bottom first level; and,
forming each second electrical interface on the uLED well bottom second level.

### Claim 29 (depends on 15)

The method of claim 15 wherein forming the stack of thin films includes:
forming each uLED well comprising a bottom surface, sidewalls, and a first electrical interface formed on the uLED well bottom surface connected to the LED control matrix;
fluidically depositing vertical structure uLEDs in the uLED wells, each vertical structure uLED comprising;
a bottom surface deposited overlying a corresponding uLED well bottom surface;
a top surface;
a first electrical contact formed on the uLED bottom surface;
a second electrical contact formed on the uLED top surface;
annealing the substrate to electrically connect each uLED first electrical contact to a corresponding uLED well first electrical interface;
forming a plurality of OLED wells in the top surface of the stack, each OLED well comprising a bottom surface, sidewalls, and a first electrode formed on the OLED well bottom surface and connected to the LED control matrix;
forming an OLED heterostructure overlying the first electrode of each OLED well; and,
wherein forming the electrical interface matrix layer includes forming a second electrode overlying each OLED heterostructure connected to a reference voltage, and forming reference voltage connection to the second electrical contact of each uLED.

### Claim 30 (depends on 29)

The method of claim 29 wherein the OLED heterostructures are formed subsequent to annealing the substrate.

### Claim 31 (depends on 15)

The method of claim 15 wherein populating the wells with LEDs includes populating the wells with LEDs having a flat circular disk shape.

### Claim 32

A method for fabricating a hybrid light emitting diode (LED) emissive display, the method comprising:
providing a substrate;
forming a stack of thin-film layers overlying a top surface of the substrate, with a plurality of wells formed in a top surface of the thin film stack, and with adjacent wells separated by well sidewalls;
using a fluidic deposition method, populating a first plurality of wells with inorganic micro LEDs (μLEDs);
fabricating organic LEDs (OLEDs) in a second plurality of wells; and,
forming an electrical interface matrix layer overlying the stack, connected to each LED.

### Claim 33 (depends on 32)

The method of claim 32 wherein the step of fabricating the OLEDs occurs before the step of fluidically depositing the μLEDs; and,
the method further comprising:
electrically connecting each μLED to at least one electrical interface formed on a well bottom surface using a process selected from the group consisting of cold welding and low temperature ultrasonic bonding.

### Claim 34 (depends on 32)

The method of claim 32 wherein the step of fabricating the OLEDs occurs after the step of fluidically depositing the μLEDs; and,
the method further comprising:
electrically connecting each μLED to at least one electrical interface formed on a well bottom surface using an annealing process.

### Claim 35 (depends on 32)

The method of claim 32 wherein the step of fabricating the OLEDs occurs before the step of fluidically depositing the uLEDs; and,
the method further comprising:
electrically connecting each μLED to the electrical interface matrix layer overlying the stack.

### Claim 36 (depends on 32)

The method of claim 32 wherein the uLEDs are configured with an electrical connection interface selected from the group consisting of vertical structure contacts and surface mount top surface contacts.