SiH2Cl2 DICHLOROSILANE

Another reaction uses dichlorosilane (SiH2Cl2), also with ammonia ... 

Tantalum disilicide, TaSi2, is very refractory and chemically resistant. It is deposited from the reaction of the chloride, TaCl5, with silane (SiH4), or dichlorosilane (SiH2Cl2), the latter precursor being preferred. The reaction takes place in a plasma as follows ... 

This complex functions as a safer and more convenient source of H2SiCl2. General features of the synthesis are short reaction times, high yields, simple apparatus, and a routine workup that produces very pure product. The major advantage, of course, is the elimination of the need to handle dichlorosilane. A synthesis of SiH2Ph2 from [SiH2Cl2 teeda] is included to show the utility of this new reagent. 

Pure methyldichlorosilane does not inflame by shock however, it immediately inflames by contact with minium, lead dioxide, copper and silver oxides. Pure trichlorosilane does not self-inflame in air (excluding the possibility of spark formation by electrostatic charge) neither does it self-inflame by shock. However, since technical trichlorosilane almost always contains dichlorosilane SiH2Cl2 (the boiling point is 8.3 °C), capable of self-inflaming by shock, trichlorosilane can also inflame by shock. Thus, if technical trichlorosilane contains more than 0.2% of dichlorosilane, one should avoid shocks and pushes when it contacts air. 

Tungsten silicide can be also deposited by dichlorosilane (SiH2Cl2, or DCS) reduction at higher temperatures of 500-600°C [73]. 

Silicon nitride is created by CVD process of silane (SiH4) and dichlorosilane (SiH2Cl2) in ammonia atmosphere at high temperature. The reactions for LPCVD is... 

Purification presented a much greater problem. In the early 1950 s The Siemens Company developed a method based on reaction of Si with HCl to produce dichlorosilane, SiH2Cl2, an easily evaporated liquid. The dichlorosilane is fractionally distilled and subsequently reduced in a reverse reaction to produce pure Si. (See also Chapter 4.) In 1952, W.G. Pfann created the zone refining method for further reduction of impurities, which was subsequently improved to reduce handling of the material between process steps. This method was used through the 1970 s. Around that time, improvements in the initial purification process made zone refining largely unnecessary. 

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