Three-dimensional transient mass transfer model for laser chemical vapor deposition of titanium on stationary finite slabs

A mathematical model for mass transfer inside a laser chemical vapor deposition (LCVD) chamber is presented for pure titanium deposition from titanium tetrabromide on a stainless-steel (SS 304) substrate. A set of five three-dimensional, transient, and nonlinear partial differential equations is solved to account for the diffusion of various species inside the LCVD chamber and the thermal decomposition of titanium tetrabromide, titanium dibromide, and titanium monobromide at the surface of the substrate in order to determine the thickness of the titanium film deposited on the substrate. The model is used for studying the effects of various parameters on the deposition and shape of titanium films. The parameters which were varied are as follows: laser power, activation energy, total pressure inside the LCVD chamber, and partial pressure of titanium tetrabromide. Under certain conditions, the deposited titanium film is found to have a volcanic profile.