Etch removal of current distribution layer for LED current confinement

• US 9,583,466 B2
• Filed: 12/27/2013
• Issued: 02/28/2017
• Est. Priority Date: 12/27/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: McGroddy, Kelly, Hu, Hsin-Hua, Bibl, Andreas, Chan, Clayton Ka Tsun
• Primary Examiner(s): SAYADIAN, HRAYR
• Application Number:
  US14/141,735
• Publication Number:
  US 20150187740A1
• Time in Patent Office: 1,159 Days
• Field of Search: 345/82, 257/13, 438/28
• US Class Current: 1/1
• CPC Class Codes: G09G 3/32 semiconductive, e.g. using light-emitting diodes [LED]
• CPC Class Codes: H01L 24/75 Apparatus for connecting with bump connectors or layer connectors
• 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 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 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01L 33/14 with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate

Abstract

A method and structure for forming an array of LED devices is disclosed. The LED devices in accordance with embodiments of the invention may include a confined current injection area in which a current spreading layer protrudes away from a cladding layer in a pillar configuration so that the cladding layer is wider than the current spreading layer pillar.

Claims

1. An LED device comprising:

a top current spreading layer;

a top cladding layer below the top current spreading layer;

an active layer below the top cladding layer;

a bottom cladding layer below the active layer, the bottom cladding layer including a bottom surface;

sidewalls spanning the top current spreading layer, the top cladding layer, the active layer, and the bottom cladding layer, wherein the bottom surface of the bottom cladding layer extends between the sidewalls; and

a singular bottom current spreading layer pillar below the bottom cladding layer and in direct contact with the bottom cladding layer, wherein the bottom current spreading layer pillar is centrally located at and protrudes from the bottom cladding layer, and the bottom surface of the bottom cladding layer that extends between the sidewalls is wider than a maximum width of the bottom current spreading layer pillar, and the bottom current spreading layer pillar is doped with a first dopant type and the second current spreading layer is doped with a second dopant type opposite the first dopant type.

2. The LED device of claim 1, further comprising a passivation layer spanning along the bottom surface of the bottom cladding layer and sidewalls of the bottom current spreading layer pillar.

3. The LED device of claim 2, further comprising an opening in the passivation layer on a bottom surface of the bottom current spreading layer pillar opposite the bottom cladding layer.

4. The LED device of claim 3, further comprising a conductive contact within the opening in the passivation layer and in electrical contact with the bottom current spreading layer pillar.

5. The LED device of claim 4, wherein the conductive contact is not in direct electrical contact with the bottom cladding layer.

6. The LED device of claim 1, wherein the top current spreading layer is wider than the bottom current spreading layer pillar.

7. The LED device of claim 1, wherein the bottom current spreading layer pillar is doped with a p-dopant.

8. The LED device of claim 7, wherein the bottom current spreading layer pillar comprises GaP and the bottom cladding layer comprises a material selected from the group consisting of AlInP, AlGaInP, and AlGaAs.

9. The LED device of claim 1, wherein the active layer of the LED device has a maximum width of 100 μ

m or less, and the bottom current spreading layer pillar maximum width is 10 μ

m or less.

10. The LED device of claim 1, wherein the active layer of the LED device has a maximum width of 20 μ

m or less, and the bottom current spreading layer pillar maximum width is 10 μ

m or less.

11. The LED device of claim 1, wherein the active layer includes 1-3 quantum well layers.

12. A display system comprising:

a display substrate including a display area;

an LED device bonded to the display substrate within the display area and in electrical connection with working circuitry in the display substrate, the LED device comprising;

a top current spreading layer;

a top cladding layer below the top current spreading layer;

an active layer below the top cladding layer;

a bottom cladding layer below the active layer, the bottom cladding layer including a bottom surface;

sidewalls spanning the top current spreading layer, the top cladding layer, the active layer, and the bottom cladding layer, wherein the bottom surface of the bottom cladding layer extends between the sidewalls; and

a singular bottom current spreading layer pillar below the bottom cladding layer and in direct contact with the bottom cladding layer, wherein the bottom current spreading layer pillar is centrally located at and protrudes from the bottom cladding layer, and the bottom surface of the bottom cladding layer that extends between the sidewalls is wider than a maximum width of the bottom current spreading layer pillar, and the bottom current spreading layer pillar is doped with a first dopant type and the second current spreading layer is doped with a second dopant type opposite the first dopant type.

13. The display system of claim 12, wherein the LED device is in electrical connection with a micro chip bonded to the display substrate within the display area.