Quartz glass is a material with a combination of superior characteristics. These include (1) high purity, (2) superior high temperature stability, (3) superior light transmittance, (4) high chemical resistance , and (5) high level of homogeneity.
Quartz glass has an extremely high purity. In the semiconductor production process, where ever higher integration occurs, even the smallest microscopic impurities are unwanted. Thus, for the quartz glass used in reaction chambers and other parts of the production process, the requirements for purity are extremely strict. Shin-Etsu Quartz Products Co., Ltd. has consistently pursued the development of products of even higher purity. As well as its high-purity transparent quartz glass from which alkali metallic impurities have been removed, the Company has also developed an ultra-pure synthetic quartz glass.
Quartz glass has a combination of superior stability at high temperature properties with an extremely low thermal expansion coefficient. In the high-temperature processes employed in the manufacture of semiconductors, including the heat treatment process, quartz glass is widely used, as a material with high heat-resistant shape stability characteristics, for furnace tubes, boats, and so on. In addition, since quartz glass is a non-crystalline solid, it can also withstand extreme changes in temperature.
Compared with ordinary glass types, transparent quartz glass has light-transmittance characteristics that are extremely high over all wavelengths, from ultraviolet to infrared. Thus this quartz glass is used as lens material for exposure devices utilized in semiconductor and liquid crystal manufacturing, for optical fiber, and as a material for lamps. Especially in the short-wavelength ultraviolet ranges, quartz glass shows superior transmittance characteristics not achieved with any other type of glass.
Since chemicals are also used in the semiconductor manufacturing process, chemical resistance is also required. Only a limited number of chemicals, including hydrofluoric acid, are capable of eroding quartz glass.
Quartz glass is also used as a lens material in photo lithography equipment which require a high level of homogeneity.