Light emitting diode having vertical topology and method of making the same
An LED having vertical topology and a method of making the same is capable of improving a luminous efficiency and reliability, and is also capable of achieving mass productivity. The method includes forming a semiconductor layer on a substrate; forming a first electrode on the semiconductor layer; forming a supporting layer on the first electrode; generating an acoustic stress wave at the interface between the substrate and semiconductor layer, thereby separating the substrate from the semiconductor layer; and forming a second electrode on the semiconductor layer exposed by the separation of the substrate.
1. A light emitting device, comprising:
a supporting layer;
a semiconductor structure on the supporting layer, the semiconductor structure comprising a first surface, a second surface opposite the first surface, and an inclined side surface with reference to the first surface;
a light-extraction structure that is part of the second surface of the semiconductor structure;
a passivation layer around the semiconductor structure;
a connection metal layer between the supporting layer and the first surface of the semiconductor structure and between the supporting layer and the passivation layer, a width of the connection metal layer in a width direction perpendicular to a thickness direction of the supporting layer being wider than a width of the light-extraction structure in the width direction;
a first electrode between the connection metal layer and the first surface of the semiconductor structure, wherein the first electrode comprises:
a reflective electrode; and
an ohmic electrode on the reflective electrode; and
a second electrode on the second surface of the semiconductor structure.
2. The device according to claim 1 , wherein the width of the connection metal layer in the width direction comprises:
a first width of a first part of the connection metal layer between the supporting layer and the first surface of the semiconductor structure; and
a second width of a second part of the connection metal layer disposed between the supporting layer and the passivation layer, the second part being adjacent to the first part of the connection metal layer.
3. The device according to claim 1 , wherein the connection metal layer comprises at least one of Cu, Au, Sn, In, Ag, an alloy of any combination thereof, and a stack of any combination thereof.
4. The device according to claim 1 , wherein the connection metal layer comprises:
a first layer;
a diffusion barrier layer on the first layer; and
a second layer on the diffusion barrier layer.
5. The device according to claim 4 , wherein the first layer comprises an Au layer or a Cu layer.
6. The device according to claim 4 , wherein the diffusion barrier layer comprises at least one of Ni, W, Ti, and Pt.
7. The device according to claim 4 , wherein the second layer comprises at least one of Ni, W, Ti, Pt, Au, Pd, Cu, Al, Cr, Ag, and an alloy of any combination thereof.
8. The device according to claim 1 , wherein the light-extraction structure comprises irregularities on a surface of the semiconductor structure.
9. The device according to claim 1 , wherein the passivation layer comprises at least one of SiO 2 , SiN, epoxy-based photoresist, acrylic-based photoresist, SOG, and polyimide.
10. The device according to claim 1 , wherein the passivation layer comprises at least two layers, the passivation layer comprising:
a first passivation layer; and
a second passivation layer on the first passivation layer.
11. The device according to claim 1 , wherein the reflective electrode comprises at least one of Ag or Al.
12. The device according to claim 1 , wherein the thickness of the reflective electrode is in a range of about 10 nm to 500 nm.
13. The device according to claim 1 , wherein the thickness of the reflective electrode is more than 500 nm.
14. The device according to claim 1 , wherein the connection metal layer has a multi-layer structure.
15. The device according to claim 1 , wherein the connection metal layer is a reflective layer.
16. The device according to claim 1 , wherein the connection metal layer is a bonding layer for attaching the supporting layer.
17. The device according to claim 1 , wherein the supporting layer comprises a semiconductor layer.
18. The device according to claim 1 , wherein the semiconductor structure comprises:
a p-type semiconductor layer;
an active layer on the p-type semiconductor layer; and
an n-type semiconductor layer on the active layer.
19. The device according to claim 1 , where the connection metal layer includes a step-down portion on a fringe of the first surface of the semiconductor structure, the step-down portion being filled with the passivation layer that extends to the semiconductor layer therefrom to protect the inclined side surface of the semiconductor structure.
20. The device according to claim 1 , wherein a width of the first electrode in the width direction is smaller than the width of the connection metal layer.