GB1128757A - Vapor deposition process for producing ªß-silicon carbide - Google Patents

Abstract

1,128,757. #-Silicon carbide. TEXAS INSTRUMENTS Inc. 5 May, 1966, No. 19961/66. Heading C1A. A layer of #-SiC is produced by introducing a gaseous stream containing Si- and C-bearing compounds and H 2 into a reaction zone containing a heated substrate such that a quiescent zone is established adjacent to the substrate through which the gases diffuse and react to deposit SiC. The product may be stoichiometric, or may have up to 1% excess C or up to 40% excess Si. The substrate, which is heated to 900-1470‹ C., may be a filament of Ta, SiC or graphite, heated by direct passage of electric current using water-cooled electrodes (Fig. 1, not shown), or a graphite crucible, heated by R.F. coils (Fig. 2, not shown). Alternatively, a carbon body with depressions in it may be used, and the carbon subsequently burnt off to give boat-shaped articles. The Si and C source may be in the same compound, e.g. CH 3 SiCl 3 , (CH 3 ) 2 SiCl 2 , (CH 3 ) 3 SiCl or (CH 3 ) 4 Si, or in different compounds, e.g. C from methane, ethane, propane, benzene, toluene, xylene, ethylene, or propylene, and Si from SiCl 4 , SiBr 4 , SiI 4 , mono-, di- or tri-, chloro-, bromo-, or iodo-silane. The mole ratio CH 3 SiCl 3 /H 2 may be 4À2-99.