Chip scale light emitting device with metal pillars in a molding compound formed at wafer level
View Patent ↗Thick metal pillars are formed upon light emitting dies while the dies are still on their supporting wafer. A molding compound is applied to fill the space between the pillars on each die, and contact pads are formed atop the pillars. The metal pillars provide electrical contact between the contact pads and the electrical contacts of each light emitting die. The metal pillars maybe formed upon an upper metal layer of each die, and this upper metal layer maybe patterned to provide connections to individual elements within the die.
1. A method comprising:
forming a light emitting structure on a substrate, the light emitting structure including an active region sandwiched between an N-region and a P-region, and contacts to the N-region and the P-region,
forming a first metal segment that is coupled to the contact to the N-region and a second metal segment that is coupled to the contact to the P-region,
forming a plurality of metal pillars for the light emitting structure, the metal pillars including at least one first metal pillar coupled to the first metal segment, at least one second metal pillar coupled to the second metal segment, and at least one third pillar that is inactive and not electrically connected to any light emitting structure, so that no current flows through the third pillar during operation of the light emitting structure,
forming a filler material that occupies spaces between the metal pillars,
forming a plurality of metal pads include a first metal pad that is coupled to the first metal pillar and a second metal pad that is coupled to the second metal pillar, the first and second metal pads being situated to provide external connection to the N-region and P-region via the first and second metal pillars.
2. The method of claim 1 , wherein the light emitting structure is one of a plurality of light emitting structures that are formed on the substrate.
3. The method of claim 2 , wherein the light emitting structures are separated from each other by streets, and the method includes forming individual light emitting devices by slicing through the streets.
4. The method of claim 3 , including detaching the light emitting structures from the substrate.
5. The method of claim 2 , including detaching the light emitting structures from the substrate.
6. The method of claim 1 , wherein the filler material has a coefficient of thermal expansion that is not significantly different from a coefficient of thermal expansion of the P-region.
7. The method of claim 1 , wherein the at least one first metal pillars include a plurality of the first pillars that provide coupling between the first pad and the first metal segment and the at least one second metal pillars include a plurality of the second pillars that provide coupling between the second pad and the second metal segment.
8. The method of claim 1 , wherein the light emitting structure includes a plurality of light emitting elements, and the method includes forming at least one third metal segment that interconnects at least two of the light emitting elements.
9. A light emitting device comprising:
a light emitting structure comprising an N-region, a P-region, an active region that is sandwiched between the N-region and the P-region, a first contact to the N-region and a second contact to the P-region,
a plurality of metal pillars for the light emitting structure, the metal pillars including at least a first pillar coupled to the first contact and at least a second pillar coupled to the second contact,
a filler material that occupies space between the pillars, and
a first pad and second pad that are coupled to the first pillar and second pillar, respectively, and provide external coupling to the N-region and P-region via the first and second pillars,
wherein the plurality of pillars further includes one or more inactive pillars that are not connected to any light emitting structure, so that during operation of the light emitting structure, no current flows through the inactive pillars.
10. The light emitting device of claim 9 , wherein the filler material has a coefficient of thermal expansion that is not significantly different from a coefficient of thermal expansion of the P-region.
11. The device of claim 9 , wherein multiple pillars provide coupling between the first pad and the first contact and multiple other pillars provide coupling between the second pad and the second contact.
12. The device of claim 9 , wherein the light emitting structure includes a plurality of light emitting elements, and the device includes at least one metal segment that interconnects at least two of the light emitting elements.