Bis(diethylamino) silane (BDEAS) is a highly volatile precursor with a vapor pressure of 30 Torr at 70°C and is liquid at room temperature with a melting point of less than 10°C and a boiling point of 188°C. It is studied and evaluated as a liquid-phase silicon precursor in the low-temperature atomic layer deposition (ALD) of hafnium silicate films. BDEAS and TDEAH are suitable precursors for the ALD of SiO2, HfO2, or HfSiOx films when used in conjunction with ozone. The composition of various HfSiOx films evaluated from RBS spectra demonstrates excellent tunability of film composition[1].
Currently, in the method of synthesizing dialkylaminosilane by the reaction of chlorosilanes with dialkylamines as a manufacturing method of dialkylaminosilane, in addition to the target dialkylaminosilane, hydrochloride salt of dialkylamine is by-produced in large quantities, and it is therefore necessary to prevent the reduction of volumetric efficiency due to a large amount of solvent when obtaining the target dialkylaminosilane, so that it is manufactured in large quantities inexpensively.
As a solvent for reacting dialkylamine with chlorosilane, a nonprotonic polar solvent that is highly soluble in the hydrochloride salt of the dialkylamine and metal chlorides by-produced in the reaction is used, and a straight-chain hydrocarbon or a branched hydrocarbon that is highly soluble in dialkylaminosilane and has difficulty in dissolving halogen compounds is used, and thus dialkylaminosilane with a low content of halogens can be produced with high volumetric efficiency. By distillation, a high-quality dialkylaminosilane with a low halogen content (chlorine) can be obtained. Most of the existing patents and literature techniques for bis(diethylamino)silane (BDEAS) refining use distillation, and the purity of the bis(diethylamino)silane can hardly exceed 99.99%.
[1] Rajesh Katamreddy, C. Takoudis, B. Feist. “Bis(diethylamino) silane as the silicon precursor in the atomic layer deposition of HfSiOx.” Journal of The Electrochemical Society 155 1 (2008).
