Through backplane laser irradiation for die transfer
Light emitting devices can be disposed on the front side of a transparent backplane. A laser beam can be irradiated through the transparent backplane and onto a component located on the front side of the transparent backplane. In one embodiment, the component may be a solder material portion that is reflowed to bond the light emitting devices to the transparent backplane. In another embodiment, the component may be a solder material bonded to a defective bonded light emitting device. In this case, the laser irradiation can reflow the solder material to dissociate the defective bonded light emitting device from the transparent backplane. In yet another embodiment, the component may be a device component that is electrically modified by the laser irradiation.
1. A method of manufacturing an assembly of a backplane and a light emitting device, the method comprising:
providing the backplane containing first and second backplane-side bonding pads;
providing a substrate containing first and second light emitting devices thereupon, wherein a first device-side bonding pad is provided on the first light emitting device, and a second device-side bonding pad is provided on the second light emitting device;
bonding the first light emitting device to the backplane by irradiating a heating laser beam on a first solder material portion located between the first device-side bonding pad and the first backplane-side bonding pad; and
dissociating from the substrate the first light emitting device that is bonded to the backplane by irradiating an ablation laser beam through the substrate and onto each region of the substrate in contact with the first light emitting device;
wherein:
the first and second light emitting devices comprise vertical light emitting diodes in which the p-side and n-side contacts are located on opposite sides of the light emitting diode;
the substrate comprises a stack of a transparent material layer and an undoped III-V compound material layer; and
the ablation laser beam passes through the transparent material layer and ablates an irradiated portion of the undoped III-V compound material layer.
2. The method of claim 1 , wherein:
the ablation laser beam has a shorter wavelength than the heating laser beam; and
the first and second light emitting devices comprise vertical light emitting diodes in which the p-side and n-side contacts are located on opposite sides of the light emitting diode.
3. The method of claim 2 , wherein the ablation laser beam comprises an ultraviolet laser beam and the heating laser beam comprises an infrared laser beam.
4. The method of claim 1 , wherein a second solder material portion located between the second device-side bonding pad and the second backplane-side bonding pad is not irradiated by the heating laser beam such that the second light emitting device is not bonded to the backplane.
5. The method of claim 4 , further comprising separating the assembly of the backplane and the first light emitting device from the second light emitting device attached to the substrate.
6. The method of claim 5 , wherein the transparent material layer comprises sapphire.