The production of the wafer production process is very complicated-developed epitaxial wafers, the next at random in each wafer test nice, to met the requirements of good quality and other defective products (a large voltage deviation, the shorter the wavelength Ora longer length, etc.). Yield of the wafer must start doing electrodes(P pole, N pole), followed by epitaxial wafers, laser cutting and hundred percent sorting, depending on the voltage, wavelength, brightness fully automated sorting, which is formed application of led (led panel square pieces). Then visually, put a point defect or electrode wear, sorting out, these are behind the bulk crystal. The blue film is incompatible with normal delivery requirements of the chip, also naturally become edge or hair piece. Bad for the epitaxial wafer(there are some parameters do not meet the requirements), would not have to do film, just as electrode(P,N), also d not divide, it is currently on the market for application of led wafer(there is also some good stuff, such as square piece and so on).
Semiconductor manufacturers mainly use polishing Si(PW) and Si epitaxial film IC as raw material. Nineteen eighties early century starting using epitaxial films, it has a standard PW which does not have the certain electrical properties and eliminates many of the crystal growth and subsequent wafer processing of the surface and the near surface defect.
Historically, epitaxial films by Si manufacturer production and use, in the IC dosage is not big. It needs to be in single crystal Si film deposited on the surface of a thin layer of single crystal Si. General epitaxial layer thickness is 2~20 μ m, and the Si substrate thickness of 610 μ m (150mm in diameter and 725 μ m (200mm).
LED lights epitaxial film - substrate material
The substrate material is the cornerstone of led lighting industrial technology development. Different substrates require different epitaxial growth techniques, chip processing technology and device packaging technology, the substrate material determines the development path of application of led lighting technology. The substrate material of choice depends primarily on the following areas:
1, the structural characteristics is well, and the similar crystal structure of epitaxial materials and substrates, the lattice constant mismatch is small, crystal properties, the defect density.
2. Interface features are well, which is benefit for the epitaxial materials into nuclear and adhesion.
3. cheap price.