Modeling the growth of thin SnO2 films using spray pyrolysis deposition

The deposition of a thin tin oxide film allows for the manufacture of modern gas sensors to replace the bulky sensors of previous generations. Spray pyrolysis deposition is used to grow the required sensing thin films, as it can be seamlessly integrated into a standard CMOS processing sequence. A model for spray pyrolysis deposition is developed and implemented within the Level Set framework. The implementation allows for a seamless integration of multiple processing steps for the manufacture of smart gas sensor devices. From observations it was noted that spray pyrolysis deposition, when performed with a gas pressure nozzle, results in good step coverage, analogous to a CVD process. This is due to the liquid droplets evaporating prior to contact with the heated wafer surface and subsequently depositing on top of the exposed silicon in vapor form.