Numerical modelling of the droplet vaporization for design and operation of liquid-pulsed CVD

摘要

This article presents an approach for modeling the vaporization of droplets of solvent andprecursor mixture under vacuum in the pulsed-pressure CVD process. The pulsed directliquid injection apparatus with ultrasonic atomizer has been demonstrated as a controllableand reliable alternative to the bubbler and carrier gas system. Design variables include thereactor base and peak pressures, solution injection volume, precursor concentration, andreactor surface temperature in the flash evaporation zone. The numerical modeling solvesmass, heat and momentum continuity equations on liquid droplets and is intended to evaluatethe relative roles of the physical chemistry properties and reactor parameters in the fastvaporization of droplets. The sensitivity analysis proposed here shows that the vaporizationtime of the pulsed liquid CVD system is mainly dependent on the heating available in theflash evaporation zone, then on the thermodynamic properties of the liquid solution. Thepractical example of TTIP (Titanium Isopropoxide) delivery is presented to select the solventand design the thermal conditions for optimal evaporation efficiency and sharpest reactorpressure rise.