A method and apparatus for monitoring the delivery of a solid precursor from a vessel to a process chamber via a process gas produced by flowing a carrier gas into the vessel is provided. The precursor typically changes state from a solid to a gas (vapor) through a sublimation process within the chamber....http://www.google.com/patents/US20040015300?utm_source=gb-gplus-sharePatent US20040015300 - Method and apparatus for monitoring solid precursor delivery
