The localization of electronic special gas meets the historic opportunity

According to the different uses of electron gas, electron gas can be divided into more than ten categories, such as epitaxial crystal growth gas, thermal oxidation gas, epitaxial gas, doping gas, diffusion gas, chemical vapor deposition gas, injection gas, ion injection gas, plasma etching gas, carrier gas, purge gas, lithography gas, annealing gas, welding gas, sintering gas and balance gas. Table 2 lists examples of electronic gases used in the electronics industry and semiconductor device fabrication processes.

Second, the introduction of important electronic gases

1, Silane (SiH4) : the best silicon source material for epitaxial crystal growth

Silane melting point -185°C, boiling point -112°C, spontaneous combustion in the air, and air can form an explosive mixture, the explosion limit in the air is 0.8% to 98.0% volume fraction; Halogens or heavy metal halides can react violently at room temperature. Silane is heated to 400 degrees Celsius and begins to decompose into amorphous silicon and hydrogen, and more than 600 degrees Celsius decompose into crystalline silicon, and the semiconductor industry mainly uses this method to produce polysilicon. Silane is very toxic, can strongly stimulate the human respiratory tract, the victim may have headaches and nausea and other symptoms, inhalation of large amounts will cause physiological changes in the respiratory and lymphatic system. Silane is the most widely used in electronic gases, the most influential gas variety, because silane flammable, explosive, high purity requirements, technical difficulty is very difficult, so silane is also one of the important signs of a country's gas strength. As a gas source that provides silicon components, monosilane can be used to manufacture high-purity polysilicon, monocrystalline silicon, microcrystalline silicon, amorphous silicon, silicon nitride and other metal silicides. Because of its high purity and fine control, it has become an important electronic special gas that cannot be replaced by many other silicon sources. Mono-silane is widely used in the microelectronics and optoelectronics industry, for the manufacture of solar cells, flat panel displays, etc., and is the world's only large-scale production of granular high-purity silicon intermediates. Silane manufacturing can be divided into magnesium silicide process, lithium aluminum hydride process and UCC process (non-homogenization process).

2, Arsenane (AsH3) : a unique arsenic source compound, due to highly toxic domestic production is difficult

AsH3 is a colorless, highly toxic, flammable gas at room temperature and atmospheric pressure, with a garlic-like odor. Mixed with air to form a combustible mixture. Arsenane is slightly soluble in water and organic solvents, and is easy to react with potassium permanganate, bromine and sodium hypochlorite to form arsenic compounds. Arsenane is stable at room temperature and begins to decompose at 230-240°C. Arsenane is a hemolytic poison that can cause neurotoxicity. AsH3 is an indispensable basic material for GaAs, GaAsP growth, N-type silicon epitaxy, diffusion, ion implantation doping, etc. Due to its highly toxic, high purity requirements, synthesis, purification difficulty and other factors, the number of countries that can manufacture AsH3 is not large, and due to the extreme toxicity of AsH3, it is very troublesome to import in today's international background.

AsH3 is an important material for the manufacture of gallium arsenide semiconductor compound, so far there is no substitute for AsH3. Arsenane is a popular product in China, although many units claim to have arsenane production technology, but arsenane and arsenic-containing compounds are serious drugs, so it is difficult to meet the national series of production permits. In the current domestic security background, few companies are willing to take risks to carry out such work. The Tianjin explosion in 2015 increased the difficulty of the localization of China's AsH3. From the technical point of view, there are many similarities between the synthesis of arsenane and the synthesis of phosphorane, the only difference is the toxicity of the two. In 2018, the purity of high-purity phosphoane and arsenane produced by Quanjiao Nanda Optoelectronics, a holding subsidiary of Nanda Optoelectronics, reached 6N level. Relying on the parent company's mature sales channels and excellent technical support, the products have achieved major market shares in the LED industry and contributed to better sales performance.

3, nitrous oxide (N2O) : dielectric film process gas, the current domestic production capacity is about to grow

Nitrous oxide is a colorless sweet gas that can support combustion under certain conditions, but is stable at room temperature, has a slight anesthetic effect, and can cause people to laugh, commonly known as laughing gas. As an electronic gas, nitrous oxide is mainly used in the dielectric film process for the development and production of semiconductor optoelectronic devices, and is an irreplaceable key point gas that directly affects the quality of optoelectronic devices. High purity nitrous oxide is an important raw material for PECVD deposition of SiO2 film, masking film, passivation film, anti-reflection and anti-reflection film of devices. The purity of N2O directly affects the purity of SiO2 film. If the impurity content is high, the deposited SiO2 film has many particles and is not bright, resulting in uneven surface refractive index and other phenomena, which is not conducive to the process of lithography. If the trace water content in N2O is high, it can cause the hydrogen content of SiO2 film to be large, and the compactness can not meet the requirements, resulting in unstable working state of the device and weak anti-electromagnetic radiation ability. Therefore, in order to ensure the quality and reliability of photoelectric device products, the purity of nitrous oxide must be above 5N.