Site-selective deposition and micropatterning of tantalum oxide thin films using a monolayer

We developed a novel process to fabricate a micropattern of tantalum oxide thin film on a patterned self-assembled monolayer (SAM) using the gradual hydrolysis reaction of tantalum ethoxide. SAM of octadecyltrichloro-silane (OTS) was prepared on a Si substrate from an OTS solution. The OTS-SAM was irradiated with UV light through a photomask to form methyl group and silanol group patterns on a substrate. The patterned OTS-SAM was then immersed in a tantalum ethoxide solution to selectively deposit thin films on silanol group regions. Site-selective deposition of amorphous tantalum compound was realized and a micropattern of the thin films was successfully fabricated at room temperature. The thin film was characterized to have the composition, Ta2O5·4H2O (Ta2O(OH)8) by XRD, XPS, FT-IR and TG-DTA. The amorphous thin film transformed into crystalline Ta2O5 after annealing at 800 °C for 2 h in air. The feature edge acuity of the micropattern remained unchanged by the annealing and thus a micropattern of Ta2O5 thin film was successfully fabricated.