P—N separation metal fill for flip chip LEDs
A light emitting diode (LED) structure has semiconductor layers, including a p-type layer, an active layer, and an n-type layer. The p-type layer has a bottom surface, and the n-type layer has a top surface through which light is emitted. Portions of the p-type layer and active layer are etched away to expose the n-type layer. The surface of the LED is patterned with a photoresist, and copper is plated over the exposed surfaces to form p and n electrodes electrically contacting their respective semiconductor layers. There is a gap between the n and p electrodes. To provide mechanical support of the semiconductor layers between the gap, a dielectric layer is formed in the gap followed by filling the gap with a metal. The metal is patterned to form stud bumps that substantially cover the bottom surface of the LED die, but do not short the electrodes. The substantially uniform coverage supports the semiconductor layer during subsequent process steps.
1. A light-emitting device, comprising:
a semiconductor structure, including a first conductivity layer, an active layer, and a second conductivity layer, the semiconductor structure having a bottom surface and a top surface;
a first electrode opposing the bottom surface and electrically connected to the first conductivity layer, the first electrode having a first sidewall;
a second electrode opposing the bottom surface and electrically connected to the second conductivity layer, the second electrode having a second sidewall facing the first sidewall;
a dielectric layer formed on at least one of the first sidewall and the second sidewall; and
a metal layer arranged to at least partially fill a gap between the first sidewall of the first electrode and the second sidewall of the second electrode, the metal layer being electrically insulated from at least one of the first sidewall and the second sidewall by the dielectric layer.
2. The light-emitting device of claim 1 , wherein the metal layer substantially fills the gap.
3. The light-emitting device of claim 1 , wherein a first portion of the metal layer at least partially fills the gap and a second portion of the metal layer forms a first group of stud bumps.
4. The light-emitting device of claim 3 , wherein the first group of stud bumps is electrically insulated from the first electrode, the second electrode, and the first portion of the metal layer.
5. The light-emitting device of claim 1 , wherein the first conductivity layer comprises a p-type conductivity layer, and the second conductivity layer comprises an n-type conductivity layer, wherein a portion of the n-type conductivity layer is exposed through the n-type conductivity layer and the active layer for making electrical contact to the second electrode.
6. The light-emitting device of claim 1 , wherein the metal layer includes a plated metal.
7. The light-emitting device of claim 1 , wherein the metal layer comprises a plurality of stud bumps that are spaced apart from one another.
8. The light-emitting device of claim 7 , further comprising a submount having a first pad and a second pad, wherein the first electrode is coupled to the first pad via at least one of the plurality of stud bumps, and the second electrode is at least in part coupled to the second pad via at least another one of the plurality of stud bumps.
9. The light-emitting device of claim 1 , wherein a first portion of the metal layer that at least partially fills the gap is electrically connected to the first electrode by a second portion of the metal layer extending over an edge of the dielectric layer.
10. The light-emitting device of claim 1 , wherein a first portion of the metal layer at least partially fills the gap and includes a first plurality of stud bumps that are electrically connected to the first electrode.
11. The light-emitting device of claim 10 , wherein a second portion of the metal layer includes a second plurality of stud bumps that are electrically insulated from the first electrode and electrically connected to the first electrode.
12. The light-emitting device of claim 1 wherein the metal layer at least partially mechanically supports the semiconductor structure.
13. The light-emitting device of claim 1 wherein the metal layer includes a first plurality of stud bumps that are electrically connected to the first electrode, a second plurality of stud bumps that are electrically connected to the second electrode, and a third plurality of stud bumps that is situated between the first plurality of stud bumps and the second plurality of stud bumps, the third plurality of stud bumps being electrically insulated from both the first electrode and the second electrode.
14. A light-emitting device, comprising:
a semiconductor structure, including a first conductivity layer, an active layer, and a second conductivity layer, the semiconductor structure having a bottom surface and a top surface;
a first electrode opposing the bottom surface and electrically connected to the first conductivity layer, the first electrode having a first sidewall;
a second electrode opposing the bottom surface and electrically connected to the second conductivity layer, the second electrode having a second sidewall facing the first sidewall;
a dielectric layer formed over the first electrode and the second electrode, the dielectric layer having being patterned to partially expose the first electrode and the second electrode; and
a metal layer formed over the dielectric layer and arranged to at least partially fill a gap between the first layer and the second layer, the metal layer including a first portion that is electrically connected to the first electrode through the dielectric layer and a second portion that is electrically connected to the second electrode through the dielectric layer, the second portion being electrically insulated from the first portion.
15. The light-emitting device of claim 14 , comprising a submount having a first contact pad and a second contact pad, the first contact pad being coupled to the first portion via solder that is applied on the first portion of the metal layer, and the second contact pad being coupled to the second portion of the metal layer via solder that is applied on the second portion of the metal layer.
16. The light-emitting device of claim 14 , wherein the metal layer is arranged to substantially fill the gap between the first electrode and the second electrode.
17. The light-emitting device of claim 14 , wherein the metal layer is arranged to provide physical support to a portion of the semiconductor structure that is adjacent to the gap.
18. The light-emitting device of claim 14 , wherein the first portion of the metal layer is electrically insulated from the second portion of the metal layer by an insulating structure formed between the first portion of the metal layer and the second portion of the metal layer.
19. The light-emitting device of claim 18 , wherein the insulating structure is formed over the first electrode and adjacently to a portion of the first electrode that is exposed through the dielectric layer.
20. The light-emitting device of claim 14 , wherein the metal layer is formed of copper.