With the development of technology, the efficiency of LED has made great progress. In the near future, LEDs will replace existing lighting bulbs. In recent years, in the process of manufacturing LED dies/chips, a gallium nitride (GaN)-based wafer (epitaxial wafer) was first fabricated on a substrate, a material source (silicon carbide SiC) required for the wafer, and various high purity. After the inert gas such as hydrogen H2 or argon Ar is used as the carrier, the wafer can be gradually processed according to the requirements of the process. Next, the two electrodes of the LED-PN junction are processed, and the LED chips are thinned and diced. The flakes are then tested and sorted to obtain the desired LED dies. The specific process practices are not described in detail.
The following is a brief introduction to the LED chip production flow chart:
In general, the LED production process is divided into two parts:
First, a gallium nitride (GaN)-based wafer is fabricated on the liner, which is mainly done in a metal organic chemical vapor deposition wafer furnace (MOCVD). After preparing the material source and various high-purity gases required for the GaN-based wafer, the epitaxial wafer can be gradually processed according to the requirements of the process. Commonly used substrates are mainly sapphire, silicon carbide and silicon substrates, as well as GaAs, AlN, ZnO and other materials.
MOCVD uses a gas phase reactant (precursor) and a group III organometallic and a group V NH3 to react on the surface of the substrate to deposit the desired product on the surface of the substrate. By controlling the temperature, pressure, reactant concentration, and species ratio, the coating composition and crystal quality are controlled. MOCVD epitaxial furnace is the most commonly used equipment for making LED epitaxial wafers .
Then, the two electrodes of the LED PN junction are processed. Electrode processing is also a key process for making LED chips, including cleaning, evaporation, yellowing, chemical etching, fusion, and grinding. Then, the LED chips are diced, tested, and divided. Select, you can get the required LED chip. If the chip cleaning is not clean enough, the evaporation system is not normal, which may result in the metal layer evaporated (the electrode after etching) may fall off, the appearance of the metal layer is discolored, and the gold bubble is abnormal.
During the evaporation process, it is sometimes necessary to fix the chip with a spring clip, so that a pinch is generated (it must be removed in the visual inspection). Huang Guang's work includes baking, photoresist, photographic exposure, development, etc. If the development is not complete and the mask has holes, there will be more metal in the light-emitting area.
In the pre-stage process, various processes such as cleaning, evaporation, yellow light, chemical etching, fusion, grinding, etc. must use tweezers and flower baskets, carriers, etc., so there will be scratches in the die of the die.
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