Extension of contact pads to the die edge via electrical isolation
View Patent ↗Light emitting diode (LED) dies are fabricated by forming LED layers including a first conductivity type layer, a light-emitting layer, and a second conductivity type layer. Trenches are formed in the LED layers that reach at least partially into the first conductivity type layer. Electrically insulation regions are formed in or next to at least portions of the first conductivity type layer along the die edges. A first conductivity bond pad layer is formed to electrically contact the first conductivity type layer and extend over the singulation streets between the LED dies. A second conductivity bond pad layer is formed to electrically contact the second conductivity type layer, and extend over the singulation streets between the LED dies and the electrically insulated portions of the first conductivity type layer. The LED dies are mounted to submounts and the LED dies are singulated along the singulation streets between the LED dies.
1. A method for fabricating a light emitting diode (LED) structure, comprising:
forming LED layers by epitaxially growing a first conductivity type layer over a growth wafer, a light-emitting layer over the first conductivity type layer, and a second conductivity type layer over the light-emitting layer;
forming trenches along die edges to expose the first conductivity type layer at the die edges, the trenches reaching at least partially into the first conductivity type layer, the trenches forming mesa structures of LED dies;
electrically insulating regions of the exposed first conductivity type layer at the die edges by forming electrically insulating regions at the die edges; and
forming first conductivity type and second conductivity type bond pad layers over the LED dies, the first conductivity type and the second conductivity type bond pad layers extending over singulation streets between the LED dies, the first conductivity type and the second conductivity type bond pad lavers being electrically coupled to the first conductivity type and the second conductivity type layers, respectively.
2. The method of claim 1 , wherein electrically insulating the regions of the exposed first conductivity type layer at the die edges comprises implanting ions into the regions of the exposed first conductivity type layer at the die edges to form the electrically insulating regions.
3. The method of claim 1 , further comprising:
epitaxially growing a semi-insulating layer over the growth substrate before forming the LED layers, wherein:
the LED layers are formed over the semi-insulating layer;
forming trenches along the die edges to expose the first conductivity type layer at the die edges comprises performing a first etch of the LED layers down at least partially into the first conductivity type layer and performing a second etch of the LED layers down to the semi-insulating epitaxial layer; and
electrically insulating the regions of the exposed first conductivity type layer at the die edges comprises forming a dielectric layer over the LED layers, wherein the electrically insulating regions comprise the dielectric layer over the regions of the exposed first conductivity type layer at the die edges.
4. The method of claim 1 , further comprising:
mounting the LED dies to submounts on a submount wafer;
removing the growth wafer from LED dies; and
singulating the LED dies along the singulation streets, wherein the first conductivity type and the second conductivity type bond pad layers are respectively divided into first conductivity type bond pads and second conductivity type bond pads of the LED dies during singulation, the first conductivity type and the second conductivity type bond pads being electrically coupled to the first conductivity type and the second conductivity type layers, respectively.
5. The method of claim 4 , wherein one or more portions of the second conductivity type bond pads are deformed into the electrically insulating regions without contacting the first conductivity type layer during singulation.
6. The method of claim 4 , wherein the first conductivity type and the second conductivity type bond pads are electrically insulated by gaps and an underlying dielectric layer, and the first conductivity type and the second conductivity type bond pads of each LED die cover at least 85% of a surface of the LED die that faces a submount.
7. The method of claim 4 , further comprising:
forming a dielectric layer over the LED layers, wherein the first conductivity type and the second conductivity type bond pad layers are formed over the dielectric layer.
8. The method of claim 4 , further comprising:
forming a first dielectric layer over the LED layers;
forming interconnects over the first dielectric layer, the interconnects being electrically coupled to the first conductivity type layer and the second conductivity type layer; and
forming a second dielectric layer over the first dielectric layer and the interconnects, wherein the first conductivity type and the second conductivity type bond pad layers are electrically coupled by the interconnects to the first conductivity type and the second conductivity type layers.
9. A light emitting diode (LED) die, comprising:
LED layers comprising a first conductivity type layer, a light-emitting layer over the first conductivity type layer, and a second conductivity type layer over the light-emitting layer;
one or more electrically insulating regions laterally adjacent to the first conductivity type layer and along one or more die edges;
a first conductivity type bond pad electrically coupled to the first conductivity type layer, the first conductivity type bond pad extending to the die edges; and
one or more second conductivity type bond pads electrically coupled to the second conductivity type layer, the second conductivity type bond pads extending to the die edges and over the electrically insulating region.
10. The LED die of claim 9 , wherein the electrically insulating regions comprise ion implanted regions of the first conductivity type layer.
11. The LED die of claim 9 , wherein the electrically insulating regions comprise a resistively grown epitaxial layer.
12. The LED die of claim 9 , further comprising:
a semi-insulating layer, wherein the LED layers are formed over the semi-insulating layer;
regions of the first conductivity type layer exposed at the die edges down to the semi-insulating epitaxial layer; and
a dielectric layer over the LED layers, wherein the electrically insulating regions comprise the dielectric layer over the regions of the first conductivity type layer exposed at the die edges.
13. The LED die of claim 9 , wherein the second conductivity type bond pads deform into the electrically insulating regions, which prevent the second conductivity type bond pads from contacting the first conductivity type layer.
14. The LED die of claim 9 , wherein the first conductivity type and the second conductivity type bond pads are electrical insulated by gaps and an underlying dielectric layer, and the first conductivity type and the second conductivity type bond pads cover at least 85% of a surface of the LED die that faces a submount.
15. The LED die of claim 9 , further comprising:
a dielectric layer over the LED layers, wherein the first conductivity type and the second conductivity type bond pad layers are formed over the dielectric layer.
16. The LED die of claim 9 , wherein the LED structure further comprise:
a first dielectric layer over the LED layers;
interconnects over the first dielectric layer, the interconnects being electrically coupled to the first conductivity type layer and the second conductivity type layer; and
a second dielectric layer over the first dielectric layer and the interconnects, wherein the first conductivity type and the second conductivity type bond pads are electrically coupled by the interconnects to the first conductivity type and the second conductivity type layers.