Ti-silicate/Si films were synthesized using a solution deposition route, and the effects of a rapid thermal process (RIP) on the microstructure, chemical bonding state, and interfacial layer (IL) properties were investigated and correlated to the permittivity of the films. The precursor solution was prepared from Ti(IV)-isopropoxide and tetraethylorthosilicate, spin-coated on HF-treated Si substrates, dried, pyrolyzed (400 degrees C), and subjected to the RIP at 700 degrees C-1000 degrees C. The Ti-silicate film consisted of Ti-rich and Si-rich silicates after the pyrolysis and phase segregation became significant as the RIP temperature increase. The silicates segregated into TiO2-like nanocrystals and Si-richer silicate at up to 850 degrees C, and the TiO2-like nanocrystals grew remarkably while the Si-richer silicate was converted into nearly pure SiO2 at 1000 degrees C. In addition, the Ti content in the Ti-silicate layer decreased due to Ti out-diffusion to the IL and substrate. Based on HRTEM, FT-IR, XPS, and SIMS analyses, we suggest a model of phase segregation with Ti diffusion and demonstrate that the Ti diffusion can be a critical issue in applications of Ti-silicate/Si systems, in addition to other well-known phenomena, including phase segregation, TiO2 precipitation, or interface properties. (C) 2014 Elsevier B.V. All rights reserved.