Light-emitting device and manufacturing method thereof

1. A light-emitting device comprising:

a substrate;

a metal connecting structure on the substrate;

a barrier layer on the metal connecting structure, and the barrier layer comprising a first metal multilayer on the metal connecting structure and a second metal multilayer on the first metal multilayer;

a metal reflective layer on the barrier layer; and

a light-emitting stack on the metal reflective layer and the barrier layer located between the substrate and the light-emitting stack,

wherein the first metal multilayer comprises a first metal layer consisting of a first metal element and a second metal layer consisting of a second metal element, and the first metal layer is closer to the metal connecting structure than the second metal layer is,

wherein the second metal multilayer comprises a third metal layer comprising a third metal element and a fourth metal layer comprising a fourth metal element, and the third metal layer is closer to the second metal layer than the fourth metal layer is,

wherein the first metal element is different from the second metal element, and the third metal element is different from the fourth metal element, and

wherein the first metal element and the third metal element are the same element, or the second metal element and the fourth metal element are the same element.

2. The light-emitting device of claim 1 , wherein the third metal layer consists of the third metal element, and the fourth metal layer consists of the fourth metal element.

3. The light-emitting device of claim 1 , wherein the first metal element and the third metal element are the same element, and the second metal element and the fourth metal element are the same element.

4. The light-emitting device of claim 1 , wherein the first metal element and the third metal element comprise nickel (Ni) or platinum (Pt), and the second metal element and the fourth metal element comprise titanium (Ti).

5. The light-emitting device of claim 1 , wherein the metal connecting structure and the metal reflective layer comprise the same metal element.

6. The light-emitting device of claim 5 , wherein the same metal element in the metal connecting structure and the metal reflective layer is different from the first metal element, the second metal element, the third metal element, and the fourth metal element.

7. The light-emitting device of claim 5 , wherein the metal connecting structure comprises an alloy of indium (In) and gold (Au), and the same metal element in the metal connecting structure and the metal reflective layer is gold.

8. The light-emitting device of claim 1 , wherein the metal connecting structure comprises a low-temperature fusion material having a melting point lower than or equal to 300° C.

9. The light-emitting device of claim 8 , wherein the low-temperature fusion material comprises indium (In).

10. The light-emitting device of claim 1 , wherein the thicknesses of the first metal layer and the third metal layer are from about 200 Å to 800 Å.

11. The light-emitting device of claim 1 , wherein the thicknesses of the second metal layer and the fourth metal layer are from about 100 Å to 500 Å.

12. The light-emitting device of claim 1 , further comprising a dielectric layer between the metal reflective layer and the light-emitting stack, wherein the dielectric layer has a refractive index less than the refractive index of the light-emitting stack.

13. The light-emitting device of claim 12 , wherein the dielectric layer comprises a plurality of through holes which penetrate the dielectric layer.

14. The light-emitting device of claim 13 , further comprising a first transparent conductive oxide layer between the metal reflective layer and the dielectric layer, and the first transparent conductive oxide layer filling into the through holes.

15. The light-emitting device of claim 14 , further comprising a second transparent conductive oxide layer between the metal reflective layer and the first transparent conductive oxide layer, and the second transparent conductive oxide layer comprising a material different from that of the first transparent conductive oxide layer.

16. A light-emitting device comprising:

a substrate;

a metal connecting structure on the substrate;

a barrier layer on the metal connecting structure, and the barrier layer comprising at least two metal multilayers on the metal connecting structure;

a metal reflective layer on the barrier layer; and

a light-emitting stack on the metal reflective layer and the barrier layer located between the substrate and the light-emitting stack,

wherein each of the metal multilayer comprises a first metal layer consisting of a first metal element and a second metal layer consisting of a second metal element, wherein the first metal layer is closer to the metal connecting structure than the second metal layer is, and the first metal element is different from the second metal element.

17. The light-emitting device of claim 16 , wherein the first metal element comprises nickel (Ni) or platinum (Pt), and the second metal element comprises titanium (Ti).

18. The light-emitting device of claim 16 , wherein the thicknesses of the first metal layer is from about 200 Å to 800 Å, and the thicknesses of the second metal layer is from about 100 Å to 500 Å.

19. A light-emitting device comprising:

a metal connecting structure;

a barrier layer on the metal connecting structure, and the barrier layer comprising a first metal multilayer on the metal connecting structure and a second metal multilayer on the first metal multilayer;

an anti-oxidation layer between the first metal multilayer and the second metal multilayer;

a metal reflective layer on the barrier layer; and

a light-emitting stack on the metal reflective layer,

wherein the first metal multilayer comprises a first metal layer comprising a first metal element and a second metal layer comprising a second metal element, and the first metal layer is closer to the metal connecting structure than the second metal layer is,

wherein the second metal multilayer comprises a third metal layer comprising a third metal element and a fourth metal layer comprising a fourth metal element, and the third metal layer is closer to the second metal layer than the fourth metal layer is,

wherein the first metal element is different from the second metal element, and the third metal element is different from the fourth metal element, and

wherein the first metal element and the third metal element are the same element, or the second metal element and the fourth metal element are the same element.

20. The light-emitting device of claim 19 , wherein the anti-oxidation layer comprises gold (Au).