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Process for the Reduction of Halopolysilanes

IP.com Disclosure Number: IPCOM000052642D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Green, DC: AUTHOR

Abstract

Disilane and other polysilane hydrides have recently been found useful in the preparation of amorphous silicon. Compared to silane, the polysilanes give higher deposition rates and improved electrical properties.

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Process for the Reduction of Halopolysilanes

Disilane and other polysilane hydrides have recently been found useful in the preparation of amorphous silicon. Compared to silane, the polysilanes give higher deposition rates and improved electrical properties.

The methods in the literature for the preparation of these polysilanes from the corresponding halosilanes [*] require the addition of solid lithium aluminum hydride (LAH) to a solution of the halosilane in a high boiling ether at 0- 10DegreesC in vacuo. The yields vary, and a minimum amount of 7% of silane (SiH(4)) is reportedly formed. The addition of the halosilane to the LAH is reported to give lower product yields and higher amounts of silane.

The improved procedure is a method to produce silanes of the type Si(x)H(y) from the corresponding halosilanes Si(x)Cl(y) (especially Si(2)H(6) fr Si(2)Ci(6)) that allows the additon of a solution of the halosilane in di-n-buty ether to a slurry of LAH in di-n-butyl ether at 25 Degrees C and a pressure of 10 mm Hg. The yields are reproducibly near quantitative with < 1% silane formed. The product is collected in a trap maintained at or below -130 Degrees C.

This process requires, however, that the LAH be highly purified to remove alkaline impurities. The alkaline impurities result in silicon silicon bond cleavage to cause lower yields and higher amounts of silane. Their removal facilitates the preferred mode of addition of halide to LAH and gives high yields of high...