Package-Integrated Thin Film LED
First Claim
1. A method comprising:
- providing light emitting diode (LED) layers grown on a growth substrate, the LED layers comprising a first epitaxial layer of a first conductivity type, a second epitaxial layer of a second conductivity type, and an active layer disposed between the first and second epitaxial layers, wherein a primary emission surface on a first side of the first epitaxial layer is substantially parallel to the active layer, the LED layers forming at least one individual LED;
providing a package substrate comprising a support surface having one or more electrical contact pads thereon for electrical connection to the first and second epitaxial layers;
placing the LED layers attached to the growth substrate on the package substrate such that the second epitaxial layer is facing a contact pad on the package substrate;
introducing an underfill material in a void between the LED layers and the package substrate;
bonding the second epitaxial layer to the first contact pad using a metal interface disposed between the package substrate and the second epitaxial layer; and
removing the growth substrate.
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Accused Products
Abstract
LED epitaxial layers (n-type, p-type, and active layers) are grown on a substrate. For each die, the n and p layers are electrically bonded to a package substrate that extends beyond the boundaries of the LED die such that the LED layers are between the package substrate and the growth substrate. The package substrate provides electrical contacts and conductors leading to solderable package connections. The growth substrate is then removed. Because the delicate LED layers were bonded to the package substrate while attached to the growth substrate, no intermediate support substrate for the LED layers is needed. The relatively thick LED epitaxial layer that was adjacent the removed growth substrate is then thinned and its top surface processed to incorporate light extraction features. There is very little absorption of light by the thinned epitaxial layer, there is high thermal conductivity to the package because the LED layers are directly bonded to the package substrate without any support substrate therebetween, and there is little electrical resistance between the package and the LED layers so efficiency (light output vs. power input) is high. The light extraction features of the LED layer further improves efficiency.
51 Citations
19 Claims
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1. A method comprising:
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providing light emitting diode (LED) layers grown on a growth substrate, the LED layers comprising a first epitaxial layer of a first conductivity type, a second epitaxial layer of a second conductivity type, and an active layer disposed between the first and second epitaxial layers, wherein a primary emission surface on a first side of the first epitaxial layer is substantially parallel to the active layer, the LED layers forming at least one individual LED; providing a package substrate comprising a support surface having one or more electrical contact pads thereon for electrical connection to the first and second epitaxial layers; placing the LED layers attached to the growth substrate on the package substrate such that the second epitaxial layer is facing a contact pad on the package substrate; introducing an underfill material in a void between the LED layers and the package substrate; bonding the second epitaxial layer to the first contact pad using a metal interface disposed between the package substrate and the second epitaxial layer; and removing the growth substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A method comprising:
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providing light emitting diode (LED) layers grown on a growth substrate, the LED layers comprising a first epitaxial layer of a first conductivity type, a second epitaxial layer of a second conductivity type, and an active layer disposed between the first and second epitaxial layers, wherein a primary emission surface on a first side of the first epitaxial layer is substantially parallel to the active layer, the LED layers forming at least one individual LED; providing a package substrate comprising a support surface having one or more electrical contact pads thereon for electrical connection to the first and second epitaxial layers; placing the LED layers attached to the growth substrate on the package substrate such that the second epitaxial layer is facing a contact pad on the package substrate; forming a protective layer over the LED layers and the package substrate after placing the LED layers on the package substrate; bonding the second epitaxial layer to the first contact pad using a metal interface disposed between the package substrate and the second epitaxial layer; removing a portion of the protective layer overlying the growth substrate; and removing the growth substrate. - View Dependent Claims (16, 17, 18, 19)
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Specification