DISILANYL-AMINES - COMPOUNDS COMPRISING THE STRUCTURAL UNIT SI-SI-N, AS SINGLE-SOURCE PRECURSORS FOR PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION (PE-CVD) OF SILICON-NITRIDE

As potential single-source precursors for the plasma-enhanced chemical vapour deposition of silicon nitride, a series of disilanyl-amines ha s been prepared containing the structural unit Si-Si-N. Hexachlorodisi lane reacts with Et2NH to yield (Et2N)Cl2SiSiCl2(NEt2), 1, and (Et2N)2 ClSiSiCl(NEt2)2, 2, while with (i-Pr)2NH the compounds (i-Pr)2N!Cl2Si SiCl3, 3, and (i-Pr)2N!Cl2SiSiCl2N(i-Pr)2!2, 4, are formed as colour less, stable liquids (1 - 3) or solids (4). The crystal structure of 4 has been determined. The molecule shows a staggered gauche conformati on (dihedral angle N-Si-Si-N 71-degrees, Si-Si 1.670 angstrom). Compou nds 2 - 4 are converted into the corresponding hydrides 6 - 8 in good yields by reaction with LiAlH, in monoglyme, while 1 is undergoing an isomerization to give 1,1-bis(diethylamino)disilane (5) in this proces s. The disilanes 5 - 8 are colourless liquids, not spontaneously infla mmable in air. 1,2-Bis(di-i-propylamino)disilane (BIPADS), 8, was chos en for downstream mode PE-CVD of silicon nitride. With substrate tempe ratures at 300-degrees-C, high quality thin films were obtained at hig h growth rates. These films show refraction indices of 1.631 - 1.814 a nd have low carbon and very low oxygen contents, but high (Si-bound) h ydrogen contents. Good insulating properties and good resistance to aq ueous alkaline etching are further characteristics which could make BI PADS-generated films an attractive alternative to conventional plasman itride materials. BIPADS is easy to handle and reduces the hazards usu ally associated with standard silane precursors.