The metal in the silicon wafer
The properties of silicon have excellent electrical properties. The band gap is moderate, and is 1.21 ev. Higher carrier mobility, the electron mobility is 1350 cm / sec / V /, hole mobility is 480 cm / sec / v. The resistivity at room temperature (300K) up to 2.3 x 10 - Europe - cm wide, doped resistivity can be controlled in 10 - to 10 - Europe - cm, can meet the needs of manufacturing various devices. The minority carrier lifetime of the single crystal silicon is longer than that in a few tens of microseconds to 1 milliseconds. Larger thermal conductivity. The chemical property is stable, and is easy to form a stable thermal oxidation film. It can be used to realize the surface passivation and protection of the PN junction in the fabrication of planar silicon devices, and the metal oxide semiconductor structure can be formed to produce MOS field effect transistors and integrated circuits. The properties of the PN junction has good characteristics, so that the silicon device has the advantages of high pressure, the reverse leakage current, high efficiency, long service life, good reliability, good heat conduction, and in the 200 - high temperature operation etc..
Monocrystalline silicon or polycrystalline silicon chip to askSilicon is an important semiconductor material, chemical element symbol Si, the silicon used in the electronic industry should have high purity and excellent electrical and mechanical properties. Silicon is one of the largest and most widely used semiconductor materials, and its output and consumption mark the level of a country's electronics industry. In the research and production, silicon materials and silicon devices promote each other. In the Second World War, the use of silicon to produce high-frequency radar crystal detector. The purity of silicon is very low and not single crystal. In 1950, the first silicon transistor was developed to improve the interest of preparing high quality single crystal silicon. Czochralski silicon (CZ) was successfully used in 1952. In 1953, the crucible free zone melting (FZ) method was developed, which can be used for physical purification and single crystal pulling. In 1955, four pure silicon was produced by zinc reduction method, but it could not meet the requirement of manufacturing transistor. In 1956 of hydrogen reduction method of trichlorosilane. The amount of impurities in silicon and after a period of exploration after hydrogen reduction of trichlorosilane method has become a kind of main method.
By 1960, the scale of industrial production had been in this way. Silicon rectifier and thyristor has prompted the silicon material production jumped in the first semiconductor material. With the development of silicon epitaxial single crystal technology and silicon planar technology in 60s, it not only makes silicon transistor manufacturing technology mature, but also promotes the rapid development of integrated circuits. In early 80s the world's polysilicon production reached 2500 tons. Silicon is one of the promising materials for solar cells. The technology of producing solar cells with polycrystalline silicon has been mature; amorphous silicon films have been developed rapidly. Chemical element silicon. Electrically active impurities phosphorus and boron should be less than 0.4ppb and 0.1ppb in qualified semiconductor and polysilicon. A certain amount of electroactive impurities should be added to the single crystal to obtain the required conductivity and resistivity. Heavy metals such as copper, gold, iron and nonmetal are very harmful impurities. The carbon content in silicon is higher than that of 1ppm. When the carbon content is over 3ppm, the harmful effect is more significant. Oxygen content in silicon is very high. Oxygen is both beneficial and harmful. The content of oxygen in Czochralski silicon is within the range of 5 to 40ppm, and the oxygen content of the fused silica can be less than 1ppm.
