Fig. 2From: Fabrication and characterization of VOC sensor array based on SnO2 and ZnO nanoparticles functionalized by metalloporphyrinsFabrication process flow. a Si3N4 film deposition on Si wafer. b Pt deposition and patterning. c SiO2 deposition and patterning. d Si3N4/SiO2 etching to form via hole. e Si wet-etching using TMAH. f Coating of sensing materialBack to article page