Micropatterned Growth of Tin Oxide Thin Films on Si-C Linked Monolayer Template

Abstract

We have succeeded in fabricating a micropatterned SnO₂ thin film on Si substrate utilizing a Si-C linked monolayer template. The Si-C linked monolayer template was prepared by the ultraviolet (UV) lithography of 1-octadecene monolayer directly bonded to Si wafer surface. The UV irradiated area was modified into Si-O area, while nonirradiated area remained unchanged, that is, its area was composed of the alkyl chains. A film growth preferentially occurred on Si-O area in the template in an aqueous solution containing SnCl₂•2H₂O of 0.03 M at 60°C. Thin film X-ray diffraction observed that as-deposited film was composed of a cassiterite structure with low crystallinity. The tin precursor hydrolyzed with H₂O molcule and integrated onto Si-O area surface for forming tin oxide thin film. On the other hand, the methyl-terminated group tends to prevent the nucleation from the aqueous solution, because of hydrophilic/hydrophobic anti-interaction. The SnO₂ thin film with high crystallinity had a gas responsibility to the mixture gas containing H₂ of 1.0 vol%.