Integration of thin tin oxide film formation into CMOS technology is a fundamental step to realize sensitive smart gas sensor devices. Spray pyrolysis is a deposition technique which has the potential to fulfil this requirement. A model for spray pyrolysis deposition is developed and implemented within a Level Set framework. Two models for the topography modification due to spray pyrolysis deposition are presented, with an electric and a pressure atomizing nozzle. The resulting film growth is modeled as a layer by layer deposition of the individual droplets which reach the wafer surface or as a CVD-like process, depending on whether the droplets form a vapor near the interface or if they deposit a film only after surface collision.