Summary of Commonly Used High-Power LED Chip Manufacturing Methods

① Increase the size. By increasing the effective light-emitting area and size of the single LED , the current flowing through the TCL layer is evenly distributed to achieve the expected luminous flux . However, simply increasing the light-emitting area cannot solve the heat dissipation and light output problems, and cannot achieve the expected luminous flux and practical application effect.

② Silicon backplane flip-chip method. First, prepare a large-size LED chip suitable for eutectic welding , and at the same time prepare a silicon backplane of the corresponding size, and make a gold conductive layer and a lead conductive layer (ultrasonic gold wire ball solder joint) for eutectic welding on the silicon backplane, and then use eutectic welding equipment to weld the large-size LED chip and the silicon backplane together. This structure is more reasonable, taking into account both the light output problem and the heat dissipation problem. This is the current mainstream production method of high-power LEDs.

In 2001, Lumileds of the United States developed the AlGaInN power flip-chip (FCLED) structure. Its manufacturing process is as follows: first, a NiAu layer with a thickness of more than 500A is deposited on the P-type GaN on the top of the epitaxial wafer for ohmic contact and back reflection; then the P-type layer and the multi-quantum well active layer are selectively etched away using a mask to expose the N-type layer; the N-type ohmic contact layer is formed by deposition and etching. The chip size is 1mm×1mm, the P-type ohmic contact is square, and the N-type ohmic contact is inserted in it in a comb shape, which can shorten the current expansion distance and minimize the expansion resistance; then the AlGaInN chip with metallized bumps is flip-chip soldered on a silicon carrier with an anti-static protection diode ( ESD ).

③ Ceramic base flip-chip method. First, use LED chip general equipment to prepare LED chips with large light-emitting areas suitable for eutectic welding electrode structures and corresponding ceramic bases, and make eutectic welding conductive layers and lead-out conductive layers on the ceramic bases, and then use eutectic welding equipment to weld large-size LED chips and ceramic bases together. This structure takes into account both light emission and heat dissipation issues, and the ceramic bases used are high thermal conductivity ceramic plates, which have very ideal heat dissipation effects and are relatively cheap, so it is currently a more suitable base material and can reserve space for future integrated circuits and integrated packaging.

④ Sapphire substrate transition method. After growing a PN junction on a sapphire substrate according to the traditional InGaN chip manufacturing method , the sapphire substrate is cut off and then connected with traditional quaternary materials to manufacture a large-size blue light LED chip with upper and lower electrode structures.

⑤ AlGaInN silicon carbide (SiC ) back-lighting method. Cree , an American company, is the only manufacturer in the world that uses SiC substrate to manufacture AlGaInN ultra- high brightness LEDs . In recent years, the structure of its AlGaInN/SiCa chips has been continuously improved, and the brightness has been continuously improved. Since the P-type and N-type electrodes are located at the bottom and top of the chip respectively, single wire bonding is used, which has good compatibility and is easy to use, thus becoming another mainstream product in the development of AlGaInN LEDs.