AN EXPERIMENTAL KINETIC STUDY OF BORON NITRIDE CVD FROM BF₃-NH₃-Ar MIXTURES

Abstract
A proper control of the CVD of boron nitride from the B-N-H-F-Ar system, as very thin films in electronic devices or ceramic composite materials, needs a thorough knowledge of the mechanisms of the process. A detailed kinetic study is presented, which provides evidenced a transition from chemical to mass transfer control, as a function of the deposition temperature, total pressure and total flow rate. On the basis of these results, a pressure temperature diagram is proposed, which defines the boundaries of both control domains for a number of compositions of the initial gaseous mixture. For these compositions, the stoichiometry of the boron nitride deposits is given, on the basis of EPMA analysis data. Under conditions of a chemically controlled process, activation energies and apparent reaction orders with respect to NH₃ and BF₃ are reported.