Micrometric patterning process of sol-gel SnO2, In2O3 and WO3 thin film for gas sensing applications: Towards silicon technology integration

Gas sensors research moves nowadays towards new applications of traditional metal oxide gas sensors into new fields like food quality, security applications and combustion control. Besides an implementation of this kind of transducers requires often a reduction of sensor dimensions, introduction of mature silicon technology substrates and fabrication methods. This work focuses on results obtained about implementation of reliable, selective, subtractive processes to perform high resolution patterning of different metal oxide films, deposited by cheap sol-gel technology onto oxidized silicon wafer or provided with thin layers of sputtered silicon nitride. Main innovations in this paper deal with an experimental evaluation of different methods to perform etching processes for three different sol-gel metal oxide materials deposited on standard dielectric layers, and evaluation of photoresist mask chemical inertness.