US-12628689-B2 - Micro-LED displays to reduce subpixel crosstalk

Abstract

A display screen includes a backplane, an array of light-emitting diodes electrically integrated with the backplane, the array of light-emitting diodes configured to emit UV light in a first wavelength range, and a plurality of isolation walls formed on the backplane between adjacent light-emitting diodes of the array of light-emitting diodes with the isolation walls spaced apart from the light-emitting diodes and extending above the light-emitting diodes. The plurality of isolation walls include a core of a first material and a coating covering at least a portion of the core extending above the light-emitting diodes. The coating is an opaque second material having transmittance less than 1% of light in the first wavelength range.

Inventors

• Lisong Xu
• Byung Sung Kwak
• Mingwei Zhu
• Hou T. NG
• Nag B. Patibandla
• Christopher Dennis Bencher

Assignees

• APPLIED MATERIALS, INC.

Dates

Publication Date

20260512

Application Date

20220322

Claims (19)

1. 1 . A display screen, comprising: a backplane; an array of light-emitting diodes electrically integrated with the backplane, the array of light-emitting diodes configured to emit UV light in a first wavelength range; a plurality of isolation walls formed on the backplane between adjacent light-emitting diodes of the array of light-emitting diodes with the isolation walls spaced apart from the light-emitting diodes and extending above the light-emitting diodes, wherein the plurality of isolation walls include a core of a first material, and a first coating covering at least a portion a horizontal top surface of the core extending above the light-emitting diodes, wherein the first coating is an opaque second material having transmittance less than 1% of light in the first wavelength range; and a second coating covering side surfaces of the light-emitting diodes, wherein the second coating is reflective in the first wavelength range and is disposed to permit UV light to pass through the top surface of the light-emitting diodes, wherein the first coating covers side surfaces of the plurality of isolation walls, the first coating does not extend below a top surface of the array of light-emitting diodes.
2. 2 . The display screen of claim 1 , further comprising color conversion layers on each light-emitting diode to convert light in the first wavelength range to visible light in a second wavelength range.
3. 3 . The display screen of claim 1 , further comprising a dielectric layer conformally coating the array of light-emitting diodes.
4. 4 . The display screen of claim 3 , wherein the dielectric layer comprises silicon nitride.
5. 5 . The display screen of claim 3 , wherein the dielectric layer conformally coats a portion of the backplane between adjacent light-emitting diodes, and each core of the plurality of isolation walls is separated from the backplane by the dielectric layer.
6. 6 . The display screen of claim 3 , wherein the dielectric layer is disposed between light-emitting diodes of the array of light-emitting diodes and the second coating.
7. 7 . The display screen of claim 1 , wherein the first material comprises a photoresist.
8. 8 . The display screen of claim 1 , wherein the first material comprises a negative photoresist.
9. 9 . The display screen of claim 1 , wherein the first material comprises a metal.
10. 10 . The display screen of claim 1 , comprising a dielectric layer conformally covering the coating of the isolation walls.
11. 11 . The display screen of claim 10 , wherein the dielectric layer comprises silicon nitride.
12. 12 . The display screen of claim 1 , wherein the second coating is metallic.
13. 13 . A display screen, comprising: a backplane; an array of light-emitting diodes electrically integrated with the backplane, the array of light-emitting diodes configured to emit UV light in a first wavelength range; and a plurality of isolation walls formed on the backplane between adjacent light-emitting diodes of the array of light-emitting diodes with the isolation walls spaced apart from the light- emitting diodes and extending above the light-emitting diodes, wherein the plurality of isolation walls include a core of a first material, and a coating covering at least a portion a horizontal top surface of the core extending above the light-emitting diodes and side surfaces of the plurality of isolation walls, wherein the coating extends below a bottom surface of the core, wherein the coating is an opaque second material having transmittance less than 1% of light in the first wavelength range.
14. 14 . The display screen of claim 13 , wherein the coating extends over a top surface of the core.
15. 15 . A display screen, comprising: a backplane; an array of light-emitting diodes electrically integrated with the backplane, the array of light-emitting diodes configured to emit UV light in a first wavelength range; and a plurality of isolation walls formed on the backplane between adjacent light-emitting diodes of the array of light-emitting diodes with the plurality of isolation walls spaced apart from the light-emitting diodes and extending above the light-emitting diodes, wherein the plurality of isolation walls include a lower portion below a top surface of the light-emitting diodes having substantially vertical side surfaces and an upper portion above the top surface of the light-emitting diodes having canted side surfaces which are wider at a base of the upper portion than at a top of the upper portion.
16. 16 . The display screen of claim 15 , wherein the upper portion of the plurality of isolation walls extends over a portion of the top surface of the array of light-emitting diodes.
17. 17 . The display screen of claim 15 , wherein the upper portion of the plurality of isolation walls is wider than the lower portion of the plurality of isolation walls at the top surface of the array of light-emitting diodes.
18. 18 . The display screen of claim 15 , wherein the upper portion of the plurality of isolation walls is narrower than the lower portion of the plurality of isolation walls at the top of the plurality of isolation walls.
19. 19 . The display screen of claim 15 , wherein the plurality of isolation walls comprise a core of a first material, and a coating covering at least a portion of the core extending above the array of light-emitting diodes, wherein the coating is an opaque second material having transmittance less than 1% of light in the first wavelength range.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to U.S. application Ser. No. 63/166,193, filed on Mar. 25, 2021, the contents of which are hereby incorporated by reference. TECHNICAL FIELD This specification relates to producing micro-LED displays and specifically to micro-LED displays using opaque material between subpixels. BACKGROUND A light-emitting diode (LED) panel uses an array of LEDs, with individual LEDs providing the individually controllable pixel elements. Such an LED panel can be used for a computer, touch panel device, personal digital assistant (PDA), cell phone, television monitor, and the like. An LED panel that uses micron-scale LEDs based on III-V semiconductor technology (also called micro-LEDs) would have a variety of advantages as compared to OLEDs, e.g., higher energy efficiency, brightness, and lifetime, as well as fewer material layers in the display stack which can simplify manufacturing. However, there are challenges to fabrication of micro-LED panels. Micro-LEDs having different color emission (e.g., red, green and blue pixels) need to be fabricated on different substrates through separate processes. Integration of the multiple colors of micro-LED devices onto a single panel requires a pick-and-place step to transfer the micro-LED devices from their original donor substrates to a destination substrate. This often involves modification of the LED structure or fabrication process, such as introducing sacrificial layers to ease die release. In addition, stringent requirements on placement accuracy (e.g., less than 1 um) limit either the throughput, the final yield, or both. An alternative approach to bypass the pick-and-place step is to selectively deposit color conversion agents (e.g., quantum dots, nanostructures, florescent materials or organic substances) at specific pixel locations on a substrate fabricated with monochrome micro-LEDs. The monochrome micro-LEDs can generate relatively short wavelength light, e.g., purple or blue light, and the color conversion agents can convert this short wavelength light into longer wavelength light, e.g., red or green light for red or green pixels. For example, the micro-LEDs can emit in the ultraviolet wavelength range (UV-micro-LEDs), and photo-emissive quantum dot (QD) particles can be layered above UV-micro-LEDs to form a subpixel which converts UV backlight to basic colors (e.g., red, green, and blue). An array of four QD/UV-micro-LEDs subpixels, emitting red, green, blue, and white light respectively, form a pixel of a display. SUMMARY In one aspect, a method for manufacturing micro-LED displays includes depositing a first material over a substrate having a plurality of micro-LEDs such that the plurality of micro-LEDs are covered by the first material and the first material fills gaps laterally separating the micro-LEDs, removing a portion of the first material from the gaps that laterally separate the plurality of micro-LEDs to form trenches in the first material that extend to or below light-emitting layers of the micro-LEDs, depositing a second material over the substrate such that the second material covers the first material and extends into the trenches in the first material, and removing a portion of the first and second material over the plurality of micro-LEDs to expose a top surface of each of the plurality of micro-LEDs and such that a plurality of isolation walls of the second material positioned in the gaps between the plurality of micro-LEDs extends vertically higher than a top surface of the first material. The second material is an opaque material. In another aspect, a method for manufacturing micro-LED displays includes depositing a first material over a substrate having a plurality of micro-LEDs such that the plurality of micro-LEDs and substrate exposed between the plurality of micro-LEDs are covered with a first conformal layer of the first material, depositing a second material over the substrate such that the second material covers the first material and fills gaps laterally separating the micro-LEDs, removing a portion of the second material from the gaps that laterally separate the plurality of micro-LEDs to form trenches in the second material that extend to the conformal layer of the first material covering the exposed substrate between the plurality of micro-LEDs, depositing a third material over the second material such that exposed surfaces of the second material and first material are covered with a second conformal layer of the third material, depositing a fourth material over the third material such that the fourth material extends into the trenches in the third material, and removing a portion of the fourth and third material over the micro-LEDs to expose top surfaces of the micro-LEDs and such that isolation walls of the third material and fourth material positioned in the gaps between the micro-LEDs extend vertically higher than the top surface of the first mate