Numerical Modeling of the Droplet Vaporization for Design and Operation of Liquid-pulsed CVD

This article presents an approach for modeling the vaporization of droplets of solvent and precursor mixture under vacuum in the pulsed-pressure (pp) CVD process. The pulsed, direct liquid injection apparatus with ultrasonic atomizer is demonstrated as a controllable and reliable alternative to the bubbler and carrier gas system. The numerical modeling solves mass, heat, and momentum continuity equations on liquid droplets, and is intended to evaluate the relative roles of the physical chemistry properties and reactor parameters in the fast vaporization of droplets. The sensitivity analysis proposed here shows that the vaporization time into the pulsed-liquid CVD system is mainly dependent on the heating available in the flash evaporation zone, then on the thermodynamic properties of the liquid solution. The pulsed pressure CVD process using a liquid precursor droplet spray is assessed by numerical simulation. The main parameters impacting the vaporization time of the liquid droplet cloud are the enthalpies of vaporization and vapor pressures of the compounds in the mixture, the initial temperature and size of the droplets, and the temperature of the reactor wall.