Nano/micro-patterning of anatase TiO2thin film from an aqueous solution by site-selective elimination method

We proposed a novel method to fabricate nano/micro-scaled patterns of thin films and successfully fabricated patterns of anatase TiO2 thin films in an aqueous solution at 50 8C. The patterned self-assembled monolayer (SAM) having octadecyltrichlorosilane (OTS) regions and silanol regions was immersed in a solution containing a Ti precursor and subjected to ultrasonication for several hours. The difference in adhesion of thin films on substrates was employed for the site-selective elimination method. Heterogeneously nucleated TiO2 and homogeneously nucleated TiO2 particles adhering to the OTS–SAM could be easily eliminated from the substrate by ultrasonication, whereas those on silanol groups maintained their adhesion during the immersion period. TiO2 can form chemical bonds such as Ti–O–Si with silanol groups, but cannot form them with octadecyl groups, resulting in the difference in adhesion, which is the essence of the site-selectivity of this method. The site-selective elimination method can be applied to fabricate nano/micro-scaled patterns in the solution by the immersion of the substrate that has regions on which depositions adhere strongly and regions on which depositions adhere weakly, enabling elimination by treatment such as ultrasonication. © 2003 Elsevier Ltd. All rights reserved.