What is a semiconductor wafer


Silicon wafers, also called silicon wafers, are important materials for making integrated circuits. By performing photolithography and ion implantation on silicon wafers, integrated circuits and various semiconductor devices can be made. Silicon wafers are sheet-like objects made of silicon, with diameters of 6 inches, 8 inches, and 12 inches. Single crystal silicon is a single crystal of silicon, which is a relatively active non-metallic element with a basically complete lattice structure. Different directions have different properties and are a good semiconducting material. The purity requirement is 99.9999%, or even 99.9999999%, and the content of impurities is reduced to the level of 10-9. The Siemens method can be used to prepare high-purity polysilicon, and then using the polysilicon as a raw material, a rod-shaped single-crystal silicon is grown from the melt by a straight-draw method or a suspension zone melting method. Monocrystalline silicon wafers are mainly divided into 6 inches, 8 inches, 12 inches, and 18 inches according to their diameter.




Silicon (Si) is currently the most important semiconductor material. More than 95% of semiconductor chips and devices worldwide are produced using silicon wafers as a base functional material. In the foreseeable future, no other materials (such as graphene, etc.) can replace the status of silicon. Silicon wafers of various sizes and specifications are widely used in the semiconductor manufacturing industry, usually including 4 inches, 5 inches, 6 inches, 8 inches, and 12 inches. Their basic specifications are shown in the following table:




Comparison of Straight Pull Method and Zone Melt Method


The larger the size of the silicon wafer, the more chips will be cut on each wafer produced in the future, and the cost per chip will be lower. In the 1960s, there were about 0.75 inches (about 20mm) of single crystal silicon wafers. When GordonMoore proposed Moore's Law around 1965, it was still a discrete transistor-based transistor, and then began to use a small amount of 1.25-inch small silicon wafers, and the demand for 1.5-inch silicon wafers for integrated circuits increased greatly.




After that, go through 2 inches, 3 inches, and 4 inches. Next 5 inches, 6 inches, 8 inches, then 12 inches. The industry generally acknowledges that in the 1980s, 4-inch silicon chips prevailed, in the 1990s it was 6-inch chips, and in the 2000s it was 8-inch chips. Intel and IBM first built 12-inch production lines in 2002, and by 2005 20%, and 30% in 2008, when 8 inches fell to 54% and 6 inches fell to 11%. It is expected that around 2020, 18-inch (450mm) silicon wafers will begin to be used.




Development history of semiconductor wafer size


Monocrystalline silicon wafers are the raw materials for the manufacture of semiconductor silicon devices. They are used to make high-power rectifiers, high-power transistors, diodes, switching devices, etc. Its subsequent products, integrated circuits and semiconductor discrete devices, have been widely used in various fields. As an important semiconductor material, single crystal silicon has been widely used in photoelectric conversion and traditional semiconductor devices. Electrically driven light sources, such as discharge lamps, fluorescent lamps or cathode ray screens, light emitting diodes, etc. From an information perspective, technologies and components such as light emission, amplification, modulation, processing, storage, measurement, and display can be used to form optoelectronic systems with specific functions. For example, the use of optical fiber communication can achieve the purpose of rapid and large-capacity information transmission. It has greatly improved the original similar technical level.




Production process flow of semiconductor single crystal silicon wafer


Single crystal silicon wafers are cut from a series of single crystal silicon rods. The methods for preparing single crystal silicon include the direct drawing method (CZ method), zone melting method (FZ method), and epitaxial method. The fusion method is used to prepare single crystal silicon rods. The greatest demand for zone-fused silicon single crystals comes from power semiconductor devices.