What Is Trimethylsilane?
Trimethylsilane is an organosilicon compound with the chemical formula C3H10Si and CAS number 993-07-7. It is a colorless gas at room temperature, nearly odorless or with a faintly unpleasant odor. It has a molecular weight of 74.2, a melting point of -135.9 °C, a boiling point of 6.7 °C, a density of 0.638 g/cm³, and a specific gravity of 2.6, making it heavier than air. Its solubility is not well defined, but it does not react violently with water.
Trimethylsilane has a flash point below -20 °C, making it highly flammable. It ignites at room temperature but is not spontaneously combustible.
Uses of Trimethylsilane
Trimethylsilane’s primary use is in semiconductor manufacturing, particularly as a raw material for film deposition in low-k dielectric constant interlayer insulating film formation using the plasma CVD method. It is utilized for SiC, SiOC, SiO2, and SiN film materials.
Purification is crucial for its use in semiconductor production, with typical impurities including methylsilane, dimethylsilane, silane, and unreacted chlorosilane. Common purification methods include distillation, recrystallization, reprecipitation, sublimation, activated carbon filtration, and washing with an absorption solution in the pH range of 2 to 4.
Principle of Trimethylsilane
1. Method for Synthesizing Trimethylsilane
Trimethylsilane is synthesized primarily by reducing trimethylchlorosilane ((CH3)SiCl) using agents such as lithium aluminum hydride (LiAlH4) in DME or aromatic hydrocarbon solvents, lithium hydride (LiH), or diethylaluminum hydride ((C2H5)2AlH).
2. Chemical Properties of Trimethylsilane
At room temperature and atmospheric pressure, trimethylsilane is stable but may decompose to silicon carbide and hydrogen at temperatures above 500 °C. It is a flammable gas, igniting at room temperature with an ignition point of 310 °C. Proper handling to avoid fire and static electricity is necessary.
Types of Trimethylsilane
Trimethylsilane is available as high-pressure and liquefied gas products, mainly for industrial use. Storage requires keeping the container below 40 °C, in a dry, well-ventilated area away from direct sunlight. As a flammable gas, it must be stored away from fire and combustible materials.