SnO2 lithographic processing for nanopatterned gas sensors

Tin dioxide (SnO2) is widely used as sensing material in metal-oxides gas sensors. In this work we present two lithographic approaches for SnO2 patterning, an additive process and a subtractive one. In the first case patterns of SnO2 nanowires are successfully fabricated and exploited as sensing element in working devices, responses to several testing gases are satisfactorily improved with respect to continuous film devices. Regarding the subtractive process, we present reactive ion etching of SnO2 based on CF4/H-2 gas mixture. Dependence of etch rate upon H-2 concentration and effects due to Ar additions to plasma are investigated: results are discussed and a possible etching reaction is proposed, but further developments are required to increase the etch rate. (c) 2005 American Vacuum Society.