Lateral thermal dissipation LED and fabrication method thereof
A lateral thermal dissipation LED and a fabrication method thereof are provided. The lateral thermal dissipation LED utilizes a patterned metal layer and a lateral heat spreading layer to transfer heat out of the LED. The thermal dissipation efficiency of the LED is increased, and the lighting emitting efficiency is accordingly improved.
1. A lateral thermal dissipation LED, comprising:
a substrate;
an N type conductive semiconductor layer disposed on the substrate;
a light emitting layer disposed on the N type conductive semiconductor layer;
a P type conductive semiconductor layer disposed on the light emitting layer;
a heat spreading layer connecting the N type conductive semiconductor layer to a package substrate, the heat spreading layer being made by mixing silver and epoxy;
a buffer layer interposed between the substrate and the N type conductive semiconductor layer;
an undoped semiconductor layer interposed between the buffer layer and the N type conductive semiconductor layer; and
a metal layer with a pattern disposed on the undoped semiconductor layer,
wherein the pattern of the metal layer includes a plurality of holes, and the metal layer with the pattern and the N type conductive semiconductor layer have ohmic contact resistance;
wherein portions of the P type conductive semiconductor layer, the light emitting layer and the N type conductive semiconductor layer are removed to expose portions of the N type conductive semiconductor layer and the metal layer, and the heat spreading layer covers the exposed portions of the N type conductive semiconductor layer and the metal layer, wherein the n-type conductive semiconductor layer is formed within the plurality of holes, and wherein the heat spreading layer partially covers two side surfaces of the metal layer and a top surface of the metal layer which is orthogonal to the side surfaces of the metal layer.
2. The lateral thermal dissipation LED of claim 1 , wherein the light emitting layer is a single quantum well layer or a multiple quantum well layer.
3. The lateral thermal dissipation LED of claim 1 , further comprising a P type electrode and an N type electrode, wherein the P electrode is disposed on the P type conductive semiconductor layer, and the N type electrode is disposed on the exposed portion of the N type conductive semiconductor layer.
4. The lateral thermal dissipation LED of claim 3 , further comprising a protecting layer covering the N type conductive semiconductor layer and the P type conductive semiconductor layer, wherein the N type electrode and the P type electrode are not covered with the protecting layer.
5. A method for manufacturing a lateral thermal dissipation LED, comprising steps of:
providing a substrate;
forming a buffer layer on the substrate;
forming an undoped semiconductor layer on the buffer layer;
forming a metal layer with a pattern on the undoped semiconductor layer, wherein the pattern of the metal layer includes a plurality of holes, and the material of the metal layer is chromium or tungsten;
forming an N type conductive semiconductor layer on the metal layer;
forming a light emitting layer on the N type conductive semiconductor layer;
forming a P type conductive semiconductor layer on the light emitting layer; and
forming a heat spreading layer on the N type conductive semiconductor layer, the heat spreading layer being made by mixing silver and epoxy;
wherein portions of the P type conductive semiconductor layer, the light emitting layer and the N type conductive semiconductor layer are removed by photolithography and etching to expose portions of the N type conductive semiconductor layer and the metal layer, and the heat spreading layer covers the exposed portions of the N type conductive semiconductor layer and the metal layer, wherein the n-type conductive semiconductor layer is formed within the plurality of holes, and wherein the heat spreading layer partially covers two side surfaces of the metal layer and a top surface of the metal layer which is orthogonal to the side surfaces of the metal layer.
6. The method of claim 5 , wherein the lateral thermal dissipation LED is a Group III-V nitride LED or a Group II-VI nitride LED, and the light emitting layer is a single quantum well layer or a multiple quantum well layer.
7. The method of claim 5 , wherein the pattern of the metal layer is formed on the undoped semiconductor layer by photolithography and etching after evaporation or sputtering.
8. The method of claim 5 , further comprising a P type electrode and an N type electrode, wherein the P electrode is disposed on the P type conductive semiconductor layer, and the N type electrode is disposed on the exposed portion of the N type conductive semiconductor layer.
9. The method of claim 8 , further comprising a step of forming a protecting layer on the N type conductive semiconductor layer and the P type conductive semiconductor layer, wherein the N type electrode and the P type electrode are not covered with the protecting layer, the material of the protecting layer is SiO 2 , Si 3 N 4 , or SiON, and the protecting layer is formed by chemical vapor deposition (CVD) or plasma enhanced chemical vapor deposition (PECVD).