Examples of the silane compounds as exemplified above of which a part or all of hydrogen atoms are substituted with halogen atoms may include halo-substituted chain or cyclic silane compounds represented by Si.sub.r H.sub.s X.sub.t (wherein X ishalogen atom, r is an integer of 1 or more, preferably 1 to 10, more preferably 3 to 7, s+t= 2r+2 or 2r) such as SiH.sub.3 F, SiH.sub.3 Cl, SiH.sub.3 Br, S