Flip-chip light emitting device and production method thereof
A flip-chip light emitting device includes a substrate, a light-emitting layer, a bonding layer disposed between the substrate and the light-emitting layer, and a protective insulating layer disposed over the light-emitting layer and the bonding layer. The bonding layer has first and second upper surfaces that respectively have different first and second roughnesses.
1 . A flip-chip light emitting device comprising:
a substrate;
an epitaxial light-emitting layer having a top surface and a bottom surface that is opposite to said top surface and faces toward said substrate;
a bonding layer disposed between said substrate and said light-emitting layer; and
a protective insulating layer disposed over said light-emitting layer and said bonding layer,
wherein said bonding layer has an outer section, an inner section surrounded by said outer section, a first upper surface that is formed on said outer section, that faces away from said substrate, and that is bonded to said protective insulating layer, and a second upper surface that is formed on said inner section, that faces away from said substrate, and that is bonded to said light-emitting layer, said first and second upper surfaces respectively having first and second roughnesses, said first roughness of said first upper surface being smaller than said second roughness of said second upper surface, a height of said first upper surface from said substrate being lower than a height of said second upper surface from said substrate, and wherein:
said light-emitting layer further has a side wall that interconnects said top surface and said bottom surface of said light-emitting layer;
said bonding layer further has a lateral wall that extends downwardly from said second upper surface to said first upper surface of said bonding layer, that extends around said inner section of said bonding layer, and that isolates said inner section of said bonding layer from said outer section of said bonding layer, said second upper surface being entirely higher than said first upper surface, said lateral wall of said bonding layer being flush with said side wall of said light-emitting layer; and
said protective insulating layer is disposed over said top surface and said side wall of said light-emitting layer, and over said first upper surface and said lateral wall of said bonding layer.
2 . The flip-chip light emitting device as claimed in claim 1 , wherein said bonding layer has a first bonding sub-layer that is disposed on said substrate, and a second bonding sub-layer that is disposed on said first bonding sub-layer opposite to said substrate.
3 . The flip-chip light emitting device as claimed in claim 2 , wherein said inner section having said first and second bonding sub-layers, said outer section of said bonding layer has only said first bonding sub-layer.
4 . The flip-chip light emitting device as claimed in claim 2 , wherein said inner section having said first and second bonding sub-layers, said outer section of said bonding layer has both of said first bonding sub-layer and said second bonding sub-layer.
5 . The flip-chip light emitting device as claimed in claim 1 , wherein said lateral wall of said bonding layer has a roughness smaller than that of said first upper surface of said bonding layer.
6 . The flip-chip light emitting device as claimed in claim 2 , wherein said second bonding sub-layer of said bonding layer is thinner than said first bonding sub-layer of said bonding layer.
7 . The flip-chip light emitting device as claimed in claim 2 , wherein a refractive index of said second bonding sub-layer of said bonding layer is higher than a refractive index of said first bonding sub-layer of said bonding layer.
8 . The flip-chip light emitting device as claimed in claim 4 , wherein said second bonding sub-layer of said bonding layer has an inner segment disposed between said light-emitting layer and said first bonding sub-layer of said bonding layer, and an outer segment disposed between said protective insulating layer and said first bonding sub-layer of said bonding layer, said inner segment of said second bonding sub-layer having a thickness larger than that of said outer segment of said second bonding sub-layer.
9 . The flip-chip light emitting device as claimed in claim 8 , wherein said first bonding sub-layer has an inner segment disposed between said substrate and said inner segment of said second bonding sub-layer, said inner segment of said second bonding sub-layer is smaller in thickness than said inner segment of said first bonding sub-layer.
10 . The flip-chip light emitting device as claimed in claim 2 , wherein said first bonding sub-layer of said bonding layer has said first upper surface of said bonding layer, and contacts said protective insulating layer.
11 . The flip-chip light emitting device as claimed in claim 3 , wherein said second bonding sub-layer of said bonding layer has said first upper surface of said bonding layer, and contacts said protective insulating layer.
12 . The flip-chip light emitting device as claimed in claim 2 , wherein said second bonding sub-layer of said bonding layer is made from aluminum oxide.
13 . The flip-chip light emitting device as claimed in claim 2 , wherein said first bonding sub-layer of said bonding layer is made from silicon oxide.
14 . The flip-chip light emitting device as claimed in claim 1 , wherein said bonding layer has a thickness ranging from 1 μm to 5 μm.
15 . The flip-chip light emitting device as claimed in claim 1 , wherein said bonding layer is made from a transparent insulation material.
16 . The flip-chip light emitting device as claimed in claim 1 , which is configured to emit light selected from the group consisting of red light and infrared light.
17 . The flip-chip light emitting device as claimed in claim 8 , wherein a thickness of said inner segment of said second bonding sub-layer of said bonding layer is smaller than one fifth of a thickness of said inner segment of said first bonding sub-layer of said bonding layer.