Gas is used in semiconductor process has been play an important role, especially in semiconductor process has been widely applied in various industries, and in every traditional ULSI, TFT - LCD to think now of microelectromechanical (MEMS) industry, at the so-called semiconductor process for product manufacturing process, the process includes, for example, the dry etching, oxidation, ion implantation, thin film deposition and so on are used to a considerable amount of gas, and the purity of the gas on the component performance has a decisive influence, product yield, the security of gas supply is about health and the safety of the plant operations.