The Relationship between the Initial Gas Ratios and the Condensed Phase Composition in the CVD of BxC with BCl3-CH4-H2 Precursors

Abstract

For the preparation of the self-healing phase BxC with BCl3-CH4-H2precursors, the production has been examined as a function of the initial gas ratios of BCl3/(BCl3+CH4) and H2/(BCl3+CH4) at given temperature and pressure. The results show that the composition of the condensed phase is quite sensitive to the molar ratio of BCl3/(BCl3+CH4) and H2/(BCl3+CH4). The ideal condition for the deposition of BxC is that the ratio of BCl3/(BCl3+CH4) is 0.8 and the H2/(BCl3+CH4) ratio ranges from 10 to 105.2. The carbon or boron-rich material is mainly controlled by the ratios of BCl3/(BCl3+CH4) and H2/(BCl3+CH4). The deposition condition of carbon-rich phase should be in low BCl3/(BCl3+CH4) (0.0~0.8) and H2/(BCl3+CH4) (10-2<102) ratios, whereas that of the boron-rich phase needs high BCl3/(BCl3+CH4) (0.8~1.0) and H2/(BCl3+CH4) (104~105) ratios.