REFLECTIVE BANK STRUCTURE AND METHOD FOR INTEGRATING A LIGHT EMITTING DEVICE

• US 20140367705A1
• Filed: 06/17/2013
• Published: 12/18/2014
• Est. Priority Date: 06/17/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: LuxVue Techonology Corporation (Apple Inc.)
• Inventors: Bibl, Andreas, Griggs, Charles R.
• Granted Patent: US 8,987,765 B2
• Time in Patent Office: Days
• US Class Current: 257/88
• CPC Class Codes: H01L 24/95 at chip-level, i.e. with connecting carried out on a plurality of singulated devices, i.e. on diced chips
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 25/165 Containers
• CPC Class Codes: H01L 25/167 comprising optoelectronic devices, e.g. LED, photodiodes
• CPC Class Codes: H01L 27/0203 Particular design considerations for integrated circuits
• CPC Class Codes: H01L 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 27/1244 for preventing breakage, peeling or short circuiting
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/12042 LASER
• CPC Class Codes: H01L 2924/12044 OLED
• CPC Class Codes: H01L 2933/0025 relating to coatings
• CPC Class Codes: H01L 2933/0033 relating to semiconductor body packages
• CPC Class Codes: H01L 2933/005 relating to encapsulations
• CPC Class Codes: H01L 2933/0066 relating to arrangements for conducting electric current to or from the semiconductor body
• CPC Class Codes: H01L 33/0008 having p-n or hi-lo junctions
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• CPC Class Codes: H01L 33/08 with a plurality of light emitting regions, e.g. laterally discontinuous light emitting layer or photoluminescent region integrated within the semiconductor body H01L27/15 takes precedence
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/30 : containing only elements of Group III and Group V of the Periodic Table
• CPC Class Codes: H01L 33/44 : characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H01L 33/486 : adapted for surface mounting
• CPC Class Codes: H01L 33/52 : Encapsulations
• CPC Class Codes: H01L 33/54 : having a particular shape
• CPC Class Codes: H01L 33/56 : Materials, e.g. epoxy or silicone resin
• 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

Light emitting devices and methods of integrating micro LED devices into light emitting device are described. In an embodiment a light emitting device includes a reflective bank structure within a bank layer, and a conductive line atop the bank layer and elevated above the reflective bank structure. A micro LED device is within the reflective bank structure and a passivation layer is over the bank layer and laterally around the micro LED device within the reflective bank structure. A portion of the micro LED device and a conductive line atop the bank layer protrude above a top surface of the passivation layer.

Claims

1. A method for integrating a light emitting device comprising:

picking up a micro LED device from a carrier substrate with a transfer head;

placing the micro LED device within a reflective bank structure formed in a bank layer;

releasing the micro LED device from the transfer head;

applying a passivation layer over the bank layer and laterally around the micro LED device within the reflective bank structure, wherein a conductive line is elevated above the reflective bank structure;

hardening the passivation layer; and

etching the passivation layer, such that a top surface of the micro LED device and a top surface of the conductive line are not covered by the passivation layer, and a portion of the micro LED device and the conductive line protrude above a top surface of the passivation layer after etching the passivation layer.

2. The method of claim 1, wherein a portion of the micro LED device and the conductive line protrude above the top surface of the passivation layer prior to etching, and the passivation layer at least partially covers the top surface of the micro LED device prior to etching.

3. The method of claim 1, further comprising leveling the passivation layer to provide a substantially flat top surface of the passivation layer across the entire area that the passivation layer covers.

4. The method of claim 3, wherein leveling the passivation layer comprises passing a roller, squeegee, or blade across the passivation layer.

5. The method of claim 4, wherein applying the passivation layer comprises slit coating or roller coating.

6. The method of claim 1, wherein hardening the passivation layer comprise UV curing.

7. The method of claim 1 further comprising:

picking up a plurality of micro LED devices from the carrier substrate with an array of transfer heads;

placing the plurality of micro LED devices within a corresponding plurality of reflective bank structures formed in the bank layer;

releasing the plurality of micro LED devices from the array of transfer heads;

applying the passivation layer over the bank layer and laterally around the plurality of micro LED devices within the corresponding plurality of reflective bank structures; and

etching the passivation layer, such that a top surface of each of the micro LED devices and the top surface of the conductive line are not covered by the passivation layer, and a portion of each of the micro LED devices and the conductive line atop the bank layer protrude above the top surface of the passivation layer after etching the passivation layer.

8. A method for integrating a light emitting device comprising:

applying a passivation layer over a bank layer and a reflective bank structure within the bank layer, wherein a conductive line atop the bank layer is elevated above the reflective bank structure and protrudes above a top surface of the passivation layer;

picking up a micro LED device from a carrier substrate with a transfer head;

placing the micro LED device within the reflective bank structure, wherein placing the micro LED device within the reflective bank structure comprises punching the micro LED device through the passivation layer;

releasing the micro LED device from the transfer head;

hardening the passivation layer; and

etching the passivation layer, such that a top surface of the micro LED device and a top surface of the conductive line are not covered by the passivation layer, and a portion of the micro LED device and the conductive line protrude above the top surface of the passivation layer after etching the passivation layer.

9. The method of claim 8, wherein a portion of the micro LED device and the conductive line protrude above the top surface of the passivation layer prior to etching, and the passivation layer at least partially covers the top surface of the micro LED device prior to etching.

10. The method of claim 8, further comprising leveling the passivation layer to provide a substantially flat top surface of the passivation layer across the entire area that the passivation layer covers.

11. The method of claim 10, wherein leveling the passivation layer comprises passing a roller, squeegee, or blade across the passivation layer.

12. The method of claim 11, wherein applying the passivation layer comprises slit coating or roller coating.

13. The method of claim 8, wherein hardening the passivation layer comprise UV curing.

14. The method of claim 8 further comprising:

applying the passivation layer over the bank layer and a plurality of reflective bank structures within the bank layer picking up a corresponding plurality of micro LED devices from the carrier substrate with an array of transfer heads;

placing the corresponding plurality of micro LED devices within the plurality of reflective bank structures, wherein placing the corresponding plurality of micro LED devices within the plurality of reflective bank structures comprises punching the plurality of micro LED devices through the passivation layer;

releasing the plurality of micro LED devices from the array of transfer heads;

hardening the passivation layer; and

etching the passivation layer, such that a top surface of each of the micro LED devices and the top surface of the conductive line are not covered by the passivation layer, and a portion of each of the micro LED devices and the conductive line atop the bank layer protrude above the top surface of the passivation layer after etching the passivation layer.

15. A light emitting device comprising:

a bank layer;

a reflective bank structure within the bank layer;

a conductive line atop the bank layer and elevated above the reflective bank structure;

a micro LED device within the reflective bank structure; and

a passivation layer that spans directly over the bank layer and within the reflective bank structure such that a portion of the passivation layer within the reflective bank structure is laterally around the micro LED device, wherein a portion of the micro LED device and the conductive line atop the bank layer protrude above a top surface of the passivation layer.

16. The light emitting device of claim 15, wherein the passivation layer comprises a substantially flat top surface across the entire area that the passivation layer covers.

17. The light emitting device of claim 15, wherein the passivation layer comprises a thermoset material.

18. The light emitting device of claim 17, wherein the thermoset material is an acrylic.

19. The light emitting device of claim 15, wherein the bank layer is formed over a thin film transistor substrate.

20. The light emitting device of claim 19, wherein the light emitting device is a display panel in a display system.

21. The light emitting device of claim 15, wherein the light emitting device is a light source in a lighting system.

22. The light emitting device of claim 15, further comprising:

a plurality of reflective bank structures within the bank layer; and

a corresponding plurality of micro LED devices within the plurality of reflective bank structures;

wherein the passivation layer spans directly over the bank layer and within the plurality of reflective bank structures such that portions of the passivation layer within the plurality of reflective bank structures are laterally around the corresponding plurality of micro LED devices, wherein a portion of each of the micro LED devices and the conductive line atop the bank layer protrude above the top surface of the passivation layer.