Fabrication method of light emitting diodes
The present invention discloses a fabrication method of light emitting diodes, which comprises the following steps: firstly, providing three sapphire wafers with each sapphire wafer having a substrate and an epitaxial layer; turning the sapphire wafers upside down and sticking an adhesive tape onto each epitaxial layer; attaching three sapphire wafers to a ceramic work piece; performing coarse grinding on the substrates with a machining table; performing fine grinding on the substrates with a polishing disc; removing the substrate completely with etching; unloading the remaining epitaxial layers and the adhesive tapes, and turning them upside down again, and stripping off the adhesive tapes; forming a conductor via joining the epitaxial layer with an electrically-conductive layer of a metal or another wafer. Thereby, the brightness of LED can be increased; the fabrication process can be accelerated; the yield can be promoted; and the cost can be reduced.
1 . A fabrication method of light emitting diodes, comprising the following steps:
providing at least one sapphire wafer having a substrate and an epitaxial layer;
turning said sapphire wafers upside down and sticking an adhesive tape onto said epitaxial layer;
fixing said adhesive tape to a ceramic work piece;
fixing said ceramic work piece to a machining table;
grinding said substrate of said sapphire wafer;
unloading said ceramic work piece, and thinning said substrate;
removing said substrate completely to reveal said epitaxial layer via an etching method;
turning said epitaxial layer and said adhesive tape, and stripping off said adhesive tape from said epitaxial layer; and
forming at least one electrically-conductive layer on the bottom surface of said epitaxial layer so that said epitaxial layer and said electrically-conductive layer can form a conductor.
2 . The fabrication method of light emitting diodes according to claim 1 , wherein said electrically-conductive layer is either a metallic layer or a wafer.
3 . The fabrication method of light emitting diodes according to claim 1 , wherein said adhesive tape is attached to said ceramic work piece with a wax and fixed to said ceramic work piece with a pressure.
4 . The fabrication method of light emitting diodes according to claim 3 , wherein said pressure ranges from 1 to 10 kg/cm 2 .
5 . The fabrication method of light emitting diodes according to claim 1 , wherein said machining table further comprising a first transmission device, and said ceramic work piece is fixed to said first transmission device with a vacuum-suction method, and said first transmission device drives said ceramic work piece to move back and forth.
6 . The fabrication method of light emitting diodes according to claim 5 , wherein said first transmission device is a motor.
7 . The fabrication method of light emitting diodes according to claim 5 , wherein said machining table further comprising a control device and a second transmission device disposed corresponding to said first transmission device, and said control device is used to control said first transmission device and said second transmission device.
8 . The fabrication method of light emitting diodes according to claim 1 , wherein said machining table further comprising a second transmission device, and said second transmission device has a grinding wheel disposed corresponding to said sapphire wafer on said ceramic work piece, and said second transmission device drives said grinding wheel to rotate and move left or right.
9 . The fabrication method of light emitting diodes according to claim 8 , wherein said second transmission device is a motor.
10 . The fabrication method of light emitting diodes according to claim 8 , wherein said machining table further comprises at least one coolant nozzle to spray a liquid coolant in order to cool said sapphire wafer and said grinding wheel.
11 . The fabrication method of light emitting diodes according to claim 8 , wherein said grinding wheel comprises diamond.
12 . The fabrication method of light emitting diodes according to claim 8 , wherein said machining table further comprises a control device and a first transmission device disposed corresponding to said second transmission device, and said control device is used to control said first transmission device and said second transmission device.
13 . The fabrication method of light emitting diodes according to claim 1 , wherein said substrate is ground to a thickness of from 50 to 200 μm.
14 . The fabrication method of light emitting diodes according to claim 1 , wherein said substrate is thinned via that said ceramic work piece is disposed on a polishing disc and thinned with a polishing solution to reduce the thickness of said substrate of said sapphire wafer.
15 . The fabrication method of light emitting diodes according to claim 1 , wherein said substrate is thinned to a thickness less than 10 μm.
16 . The fabrication method of light emitting diodes according to claim 1 , wherein said etching method is either a dry etching method or a wet etching method.