Micro LED based display panel
Light emitting structures and methods of fabrication are described. In an embodiment, LED coupons are transferred to a carrier substrate and then patterned to LED mesa structures. Patterning may be performed on heterogeneous groups of LED coupons with a common mask set. The LED mesa structure are then transferred in bulk to a display substrate. In an embodiment, a light emitting structure includes an arrangement of LEDs with different thickness, and corresponding bottom contacts with different thicknesses bonded to a display substrate.
1. A light emitting structure comprising:
a substrate including a planar top bonding surface including a top surface dielectric bonding layer and a first group of electrode pads;
an emission layer stack-up hybrid bonded to the planar top bonding surface of the substrate, the emission layer stack-up including:
a first group of light emitting diodes (LEDs);
a dielectric bonding layer spanning underneath the first group of LEDs; and
a first group of bond posts connected to the first group of LEDs and extending through the dielectric bonding layer;
a contact terminal extending through the dielectric bonding layer;
wherein the contact terminal and each bond post is metal-metal bonded with a corresponding electrode pad of the first group of electrode pads, and the dielectric bonding layer is dielectric-dielectric bonded with the top surface dielectric bonding layer of the substrate; and
a top electrode layer spanning over the first group of LEDs and in electrical connection with the contact terminal.
2. The light emitting structure of claim 1 , wherein the dielectric bonding layer is an oxide bonding layer.
3. The light emitting structure of claim 2 , wherein the top surface dielectric bonding layer is a top surface oxide bonding layer.
4. The light emitting structure of claim 1 , wherein each LED comprises an inorganic semiconductor-based p-n diode.
5. The light emitting structure of claim 4 , further comprising a reflective metal layer laterally around each LED.
6. The light emitting structure of claim 5 , wherein the reflective metal layer is a continuous layer that spans around and underneath the LED.
7. The light emitting structure of claim 6 , further comprising a sidewall passivation layer between the LED and the reflective metal layer.
8. The light emitting structure of claim 7 , further comprising an opening in the sidewall passivation layer that exposes a bottom surface of the LED, and the reflective metal layer contacts the bottom surface of the LED in the opening.
9. The light emitting structure of claim 7 , wherein the p-n diode has a maximum width of less than 5 microns, and maximum height of less than 3 microns.
10. The light emitting structure of claim 4 , wherein each p-n diode has a maximum width of less than 5 microns, and maximum height of less than 3 microns.
11. The light emitting structure of claim 10 , wherein:
the substrate planar top bonding surface includes a second group of electrode pads; and
the emission layer stack-up includes:
a second group of LEDs;
the dielectric bonding layer spans underneath the second group of LEDs; and
a second group of bond posts connected to the second group of LEDs and extending through the dielectric bonding layer; and
wherein each bond post of the second group of bond posts is metal-metal bonded with a corresponding electrode pad of the second group of electrode pads.
12. The light emitting structure of claim 11 , wherein the first group of bond posts is thicker than the second group of bond posts.
13. The light emitting structure of claim 12 , wherein the first group of LEDs is thinner than the second group of LEDs.
14. The light emitting structure of claim 11 , further comprising an array of micro-optic elements over the first group of LEDs and the second group of LEDs.
15. The light emitting structure of claim 14 , wherein the array of micro-optic elements includes an array of half-balls.
16. The light emitting structure of claim 14 , wherein the array of micro-optic elements reflective sidewalls.
17. The light emitting structure of claim 1 , wherein the substrate includes circuitry to address the first group of LEDs.
18. The light emitting structure of claim 1 , wherein the substrate includes complementary metal-oxide-semiconductor (CMOS) circuitry.