How much do you know about silane?

Silane(SiH4) is a Colorless gas that reacts with air and can cause asphyxiation. Its synonymous name is silicon hydride. The chemical formula of silane is SiH4, and the content is as high as 99.99%. At room temperature and pressure, silane is a toxic gas with a foul odor. The melting point of silane is -185℃ and the boiling point is -112℃. At room temperature, silane is stable, but when heated to 400℃, it will completely decompose into gaseous silicon and hydrogen. Silane is flammable and explosive, and will burn explosively in air or halogen gas.

Silane has a wide range of uses. In addition to being the most effective way to attach silicon molecules to the surface of solar cells during the production process, it is also widely used in semiconductor, flat panel display, coated glass and other manufacturing plants. Silane is the silicon source for chemical vapor deposition processes such as single crystal silicon, polycrystalline silicon epitaxial wafers, and silicon dioxide, silicon nitride, and phosphosilicate glass in the semiconductor industry. It is also widely used in the production and development of solar cells, silicon copier drums, photoelectric sensors, optical fibers, and special glass.

Electronic grade silane gas is mainly used in the semiconductor industry to make high-purity polysilicon, silicon dioxide film, silicon nitride film, polysilicon isolation layer, polysilicon ohmic contact layer and heterogeneous or homogeneous silicon epitaxial growth raw materials through vapor deposition, as well as ion implantation source and laser medium. The surface of the silicon wafer and its adjacent areas are heated to provide the required energy to the reaction system. All substances in the chemical vapor deposition film come from an external gas source. Atoms or molecules will be deposited on the surface of the silicon wafer to form a thin film. Electronic grade silane gas is one of the most common gases in chemical vapor deposition.

Electronic grade silane gas is mainly used in the production of TFT (thin film transistor)/LCD (liquid crystal display) in the display panel industry. Each pixel of TFT/LCD is controlled by the TFT integrated on itself, which is an active pixel. Therefore, it has the advantages of small size, light weight, low radiation, low power consumption, full color, fast speed, high contrast and brightness, large screen viewing angle, and high resolution. It is the mainstream flat display device at present. The production of TFT/LCD includes TFT array (including thin film, photolithography, etching), color filter (including black matrix film, red, green and blue film, transparent conductive layer), panel, module and other processes. In the thin film process, silane and other gases dissociate and react and deposit on the surface of the glass substrate under the action of the high-frequency alternating electric field of the CVD process (chemical vapor deposition), which can form an insulating layer resistant to water vapor and metal ion corrosion, an electron channel layer, an ohmic contact layer, and a valve-level insulating layer with high density and good insulation.

Electronic-grade silane gas is mainly used in the photovoltaic industry for the production of crystalline silicon solar cells and thin-film solar cells. Commercially produced crystalline silicon solar cells usually use polycrystalline silicon materials. During the production process, an anti-reflection film needs to be made on the light-receiving surface through chemical vapor deposition. Silane gas is required in this step. Commercially produced thin-film solar cells are divided into amorphous silicon thin films and amorphous/microcrystalline silicon laminated thin films. The latter absorbs and utilizes sunlight more fully. Both of them need to use chemical vapor deposition to make thin films during their production process. Silane gas is required in this process.

In recent years, high-tech applications of silane continue to emerge, including their use in the manufacture of advanced ceramics, composite materials, functional materials, biomaterials, high-energy materials, etc., becoming the basis for many new technologies, new materials and new devices.