Chip is the core component of LED. At present, many domestic and foreign manufacturers of LED chip, and chip classification has no unified standard, according to the power classification, there are a large power and small power; if classified by color, mainly red, green, blue three; if the classification based on the shape, generally divided into square plate, two kinds of wafer; if according to the voltage classification, is divided into low voltage and high voltage DC DC chip chip. Comparison of domestic and foreign chip technology, foreign chip technology, the domestic chip production is not heavy technology.
Substrate material and wafer growth technology
At present, the key to the development of LED chip technology is the substrate material and wafer growth technology. In addition to the traditional sapphire, silicon (Si), silicon carbide (SiC) substrate, Zinc Oxide (ZnO) and gallium nitride (GaN) is the current research focus of LED chip. At present, the market most of the sapphire or silicon carbide substrate to the epitaxial growth of wide band gap semiconductor Gan, the two kinds of materials are expensive, and is monopolized by foreign companies, and the price of silicon substrate than sapphire and SiC substrates is much cheaper, can produce greater substrate size, improve the utilization rate of MOCVD in order to improve the yield of the tube core. Therefore, in order to break through the international patent barriers, Chinese research institutions and LED companies from silicon substrate materials.
But the problem is that the high quality silicon and gallium nitride is combined with the technical difficulties of LED chip, a huge mismatch in lattice constant and thermal expansion coefficient and the density of defects caused by crack and high technical problems have long hindered the development in the field of chip.
Undoubtedly, from the point of view of the substrate, the main substrate is still sapphire and silicon carbide, but silicon has become the future development trend of the chip industry. For the price war is relatively serious China, silicon substrate is more cost and price advantage: the silicon substrate is a conductive substrate, which can not only reduce the die area, can also be a dry etching step, eliminating the epitaxial layer of gallium nitride and silicon sapphire and silicon carbide hardness than low in processing can also save some cost.
The LED industry is mostly based on the sapphire substrate of 2 inches or 4 inches, such as the use of gallium nitride silicon technology, can save at least 75% of the cost of raw materials. According to Japan Sanken electric company estimates that the cost of production of large size silicon substrate using blue alxga1 LED 90% lower than the sapphire and SiC substrates.