PROCESSING AND CHARACTERIZATION OF SN O2 THIN FILM FABRICATED MECHANISM FOR SUITABILITY OF SENSOR APPLICATIONS

Abstract

In the last few decades Tin Oxide (SnO2) based gas sensors have gained eminence. Oxide sensors are usually
screen printed on bulk heater substrates. Less power consumed thin film sensors are basically suited for battery operated
systems and are agreeable and can be incorporated with the standard silicon based electronic processing. During
electronic processing, the spin coating is also an accepted thin film fabricated mechanism. Processing of SnO2 thin films
are intended for suitability of sensor applications. Techniques such as dip coating, low rpm films using a conventional
metallographic polishing system and a specially fabricated spin coater are adapted during experimental investigation.
Assorted difficulties observed during processing of thin films and consequent thermal behavior using tin based sols. The
experimental investigation analyses and employs corrective measures at every stage of dispensation. A spin coater was
developed and employed for processing the thin films. It is modified by employing the confinement ring for uniformity
and repeatability. Thin films were coated using the sol prepared from SnCl4 and isopropyl alcohol and were heat treated
at different temperatures. The validation of the work is presented by demonstrating a method of processing crack free,
uniform SnO2 thin films using a laboratory designed, fabricated and suitably modified spin coater that runs at 4000 rpm
and their thermal treatment at 500oC in a single step.