Site-selective deposition and micropatterning of SrTiO3 thin film on self-assembled monolayers by the liquid phase deposition method

We have succeeded in site-selective deposition of SrTiO3 (STO) thin films on patterned self-assembled monolayers (SAMs) by the liquid phase deposition (LPD) method. SAMs of heptadecafluoro-1,1,2,2,-tetrahydrodecyltrichlorosilanes [HFDTS, CF3(CF2)(7)(CH2)(2)SiCl3] were prepared on Si wafers and modified by UV irradiation through a photomask. This SAM template was composed of HFDTS surfaces (Si-CF3) and silanol surfaces. The patterned SAM-covered substrate was then immersed into a (NH4)TiF6/Sr(NO3)/H2BO3 aqueous solution at 50 degreesC to deposit a solid phase. (NH4)(2)TiF6, which could form [Ti(OH)(n)F6-n](2-) slowly in an aqueous solution, was selected as a source of TiO32-. H3BO3 was a scavenger of fluorine and was used to control the reaction rate. The STO films were selectively deposited in the silanol regions. The as-deposited film was amorphous containing fluorine as a main impurity. With annealing at 500 degreesC for 2 h in air, the as-deposited film was crystallized into SrTiO3 and the fluorine was eliminated. Film morphology was characterized by both SEM and AFM. Metal-oxide-semiconductor (MOS) devices were prepared by using an as-deposited film or a crystallized film as a gate oxide. The dielectric constant of SrTiO3 thin films and the leakage current of the MOS device were evaluated. These results indicate that the SrTiO3 film fabricated by a combination of the SAM technique with LPD method through a one-step process is promising for application to dielectric films.