Elastomeric layer fabrication for light emitting diodes

Patent metadata

Field	Value
Publication number	US-10319705-B2
Application number	US-201715789275-A
Country	US
Kind code	B2
Filing date	Oct 20, 2017
Priority date	Oct 20, 2017
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

An elastomeric interface layer (elayer) is formed over multiple light emitting diode (LED) dies by depositing photoresist materials across multiple LED dies, and using the LED dies as a photolithography mask to facilitate formation of the elayer on each LED die. The elayer facilitates adhesive attachment of each LED die with a pick and place head (PPH), allowing the LED dies to be picked up and placed onto a display substrate including control circuits for sub-pixels of an electronic display. In some embodiments, the LED dies are micro-LED (μLED) dies.

First claim

What is claimed is:

1. A method, comprising:
depositing a photoresist material on and between light emitting diode (LED) dies on a carrier substrate;
applying light through the carrier substrate towards the LED dies and the deposited photoresist material, responsive to depositing the photoresist material;
absorbing a portion of the light incident on the LED dies to retain soluble first portions of the photoresist material on the LED dies;
exposing portions of photoresist material between the LED dies to another portion of the light to render second portions of the photoresist material between the LED insoluble;
removing the first portions of photoresist material, responsive to applying the light;
depositing an elastomeric material on each LED die and between the second portions of photoresist, responsive to removing the first portions; and
removing the second portions of the photoresist material responsive to depositing the elastomeric material, the elastomeric material forming elastomeric interface layers on the LED dies.

2. The method of claim 1 , further comprising:
picking up at least a portion of the LED dies on the carrier substrate by attaching a non-conformable pick-up head to the elastomeric interface layers over the LED dies; and
placing the at least a portion of the LED dies attached to the non-conformable pick-up head on a display substrate defining pixel control circuits of an electronic display.

3. The method of claim 1 , further comprising:
fabricating the LED dies on a native substrate;
attaching a carrier film capable of expanding to a first side of the LED dies on the native substrate;
detaching the native substrate from the LED dies;
singulating the LED dies attached to the carrier film;
separating the LED dies by expanding the carrier film to define the open regions between the LED dies;
bringing the carrier substrate to a second side of the LED dies, the carrier substrate including a substrate layer and an adhesive layer, the LED dies being attached to the adhesive layer of the carrier substrate with the open regions being defined between the LED dies; and
separating the carrier film from the first side of the LED dies to expose the first side of the LED dies to the depositing of the elastomeric material.

4. The method of claim 1 , wherein the carrier substrate includes an adhesive layer and a glass substrate layer, the LED dies attached to the carrier substrate by the adhesive layer.

5. The method of claim 1 , wherein:
removing the first portions of photoresist material includes dissolving the first portions with a first solvent; and
removing the second portions of the photoresist material responsive to depositing the elastomeric material includes dissolving the second portions of the photoresist material with a second solvent different from the first solvent.

6. The method of claim 5 , wherein:
the first solvent is benign to the insoluble second portions of the photoresist material; and
the second solvent is benign to the elastomeric material forming the elastomeric interface layers on the LED dies.

7. The method of claim 1 , wherein the LED dies are micro-LEDs and include Gallium nitride (GaN), gallium arsenide (GaAs), or gallium phosphide (GaP).

8. A method, comprising:
depositing a photoresist material on and at side surfaces of a light emitting diode (LED) die on a carrier substrate;
applying light through the carrier substrate towards the LED die and the deposited photoresist material, responsive to depositing the photoresist material;
absorbing a portion of the light incident on the LED die to retain a soluble first portion of the photoresist material on the LED die;
exposing portions of photoresist material at the side surfaces of the LED die to another portion of the light to render second portions of the photoresist material at the side surfaces of the LED insoluble;
removing the first portion of photoresist material, responsive to applying the light;
depositing an elastomeric material on the LED die and between the second portions of photoresist, responsive to removing the first portion; and
removing the second portions of the photoresist material responsive to depositing the elastomeric material, the elastomeric material forming elastomeric interface layer on the LED die.

9. The method of claim 8 , wherein the LED dies absorbs Ultraviolet (UV) light incident on the LED dies through the carrier substrate.

10. The method of claim 8 , further comprising:
picking up the LED die on the carrier substrate by attaching a non-conformable pick-up head to the elastomeric interface layer over the LED die; and
placing the LED die attached to the non-conformable pick-up head on a display substrate defining pixel control circuits of an electronic display.

11. The method of claim 8 , wherein the carrier substrate includes an adhesive layer and a glass substrate layer, the LED die is attached to the carrier substrate by the adhesive layer.

12. The method of claim 8 , wherein:
removing the first portion of photoresist material includes dissolving the first portion with a first solvent; and
removing the second portions of the photoresist material responsive to depositing the elastomeric material includes dissolving the second portions of the photoresist material with a second solvent different from the first solvent.

13. The method of claim 12 , wherein:
the first solvent is benign to the insoluble second portions of the photoresist material; and
the second solvent is benign to the elastomeric material forming the elastomeric interface layer on the LED die.

14. The method of claim 8 , wherein the LED die includes Gallium nitride (GaN), gallium arsenide (GaAs), or gallium phosphide (GaP).

15. The method of claim 8 , wherein the LED die is a micro-LED or vertical-cavity surface-emitting laser (VCSEL).

16. The method of claim 8 , wherein the LED die absorbs Ultraviolet (UV) light incident on the LED die through the carrier substrate.

17. An electronic display panel fabricated by a method, comprising:
depositing a photoresist material on and between light emitting diode (LED) dies on a carrier substrate;
applying light through the carrier substrate towards the LED dies and the deposited photoresist material, responsive to depositing the photoresist material;
absorbing a portion of the light incident on the LED dies to retain soluble first portions of the photoresist material on the LED dies;
exposing portions of photoresist material between the LED dies to another portion of the light to render second portions of the photoresist material between the LED insoluble;
removing the first portions of photoresist material, responsive to applying the light;
depositing an elastomeric material on each LED die and between the second portions of photoresist, responsive to removing the first portions;
removing the second portions of the photoresist material responsive to depositing the elastomeric material, the elastomeric material forming elastomeric interface layers on the LED dies
picking up at least a portion of the LED dies on the carrier substrate by attaching a non-conformable pick-up head to the elastomeric interface layers over the LED dies; and
placing the at least a portion of the LED dies attached to the non-conformable pick-up head on a display substrate defining pixel control circuits of an electronic display.

18. The electronic display panel of claim 17 , wherein:
removing the first portions of photoresist material includes dissolving the first portions with a first solvent; and

Assignees

• Facebook Tech Llc

Inventors

• Brodoceanu Daniel
• Abad Oscar Torrents

Classifications

• H10W72/0198

  batch processes · CPC title

• H10W72/07232

  Compression bonding, e.g. thermocompression bonding · CPC title

• H10W72/07204

  using temporary auxiliary members, e.g. sacrificial coatings · CPC title

• H10W72/0711

  Apparatus therefor · CPC title

• H10W72/07173

  Means for moving chips, wafers or other parts, e.g. conveyor belts · CPC title