LED backplane having planar bonding surfaces and method of making thereof
A backplane can have a non-planar top surface. Insulating material portions including planar top surface regions located within a same horizontal plane are formed over the backplane. A two-dimensional array of metal plate clusters is formed over the insulating material portions. Each of the metal plate clusters includes a plurality of metal plates. Each metal plate includes a horizontal metal plate portion overlying a planar top surface region and a connection metal portion connected to a respective metal interconnect structure in the backplane. A two-dimensional array of light emitting device clusters is bonded to the backplane through respective bonding structures. Each light emitting device cluster includes a plurality of light emitting devices overlying a respective metal plate cluster.
1. A light emitting device assembly comprising:
a backplane comprising a substrate containing metal interconnect structures;
insulating material portions having a lower elastic modulus than the substrate, wherein the insulating material portions are located over the backplane and contain a respective planar top surface region such that the planar top surface regions of the insulating material portions are located within a same horizontal plane;
a two-dimensional array of metal plate clusters, wherein each of the metal plate clusters comprises a plurality of metal plates, each metal plate including a horizontal metal plate portion overlying a planar top surface region of a respective insulating material portion and a connection metal portion extending between the horizontal metal plate portion and a respective one of the metal interconnect structures; and
a two-dimensional array of light emitting device clusters bonded to the backplane through respective bonding structures, wherein each light emitting device cluster comprises a plurality of light emitting devices overlying a respective metal plate cluster.
2. The light emitting device assembly of claim 1 , further comprising compound semiconductor material portions having irregular surface height variations located on distal surfaces of the light emitting devices, the distal surfaces being surfaces of the light emitting devices facing away from the backplane.
3. The light emitting device assembly of claim 1 , wherein the bonding structures comprise a two-dimensional array of backplane-side bonding pads located on top of the two-dimensional array of metal plate clusters, wherein each of the backplane-side bonding pads is located on a respective one of the horizontal metal plate portions.
4. The light emitting device assembly of claim 3 , wherein each of the light emitting devices within the two-dimensional array of light emitting device clusters includes a device-side bonding pad that is bonded to a respective one of the backplane-side bonding pads through a solder material portion.
5. The light emitting device assembly of claim 1 , wherein:
the metal interconnect structures are arranged to provide a rectangular two-dimensional array of gap regions in which the metal interconnect structures are not present;
the insulating material portions are located over each of the gap regions; and
the plurality of metal plates overlies a respective one of the gap regions.
6. The light emitting device assembly of claim 1 , wherein each light emitting device cluster comprises a pixel of a direct view display device.
7. The light emitting device assembly of claim 1 , wherein:
the two-dimensional array of light emitting device clusters has a same two-dimensional periodicity as the two-dimensional array of metal plate clusters; and
each of the connection metal portions contacts a tapered sidewall or a vertical sidewall of a respective one of the insulating material portions and a top surface of a respective metal interconnect structure.
8. The light emitting device assembly of claim 7 , wherein the insulating material portions are arranged as a two-dimensional array of insulating mesa structures not directly contacting one another and having a same two-dimensional periodicity as the two-dimensional array of metal plate clusters.
9. The light emitting device assembly of claim 7 , wherein:
the insulating material portions are portions of a continuous insulating material layer that covers a top surface of the backplane; and
each connection metal portion extends through a respective opening through the continuous insulating material layer.
10. The light emitting device assembly of claim 1 , wherein:
the substrate of the backplane comprises a first dielectric material having a first elastic modulus; and
the insulating material portions are located on the substrate of the backplane and comprise a second dielectric material having a second elastic modulus that is less than 80% of the first elastic modulus.