High-k titanium silicate thin films grown by reactive magnetron sputtering for complementary metal-oxide-semiconductor applications

Titanium silicate (TiSixOy) thin films have been successfully deposited by means of radio-frequency magnetron sputtering of a TiO2 /SiO2 composite target in a reactive gas atmosphere. The deposition of the films was investigated as a function of the [O-2]/([Ar]+[O-2]) flow ratio in the 0%-30% range. The bonding states and the dielectric properties of the sputter-deposited TiSixOy films were systematically investigated as a function of the O-2 flow ratio. For all the O-2 flow ratios studied, Fourier-transform infrared and x-ray photoelectron spectroscopy analyses have clearly revealed the presence of Ti-O-Si type of local environments, which are the fingerprint of the titanium silicate phase. Increasing the O-2 proportion in the sputtering chamber was found to cause a significant decrease of the deposition rate and a drastic improvement in the dielectric properties of the films. TiSixOy films exhibiting excellent dielectric properties (i.e., a dielectric constant as high as similar to20, a dissipation factor as low as 0.01, and a low leakage current density of 10(-3) A/cm(2) at 1 MV/cm) were indeed achieved under high O-2 flow ratio conditions (greater than or equal to 20%). In contrast, films deposited under low O-2 flow ratio conditions (less than or equal to 5%) have exhibited poor dielectric properties. The presence of oxygen vacancies in the films is invoked as a possible explanation for the observed variations of their dielectric properties with the O-2 flow ratio. (C) 2004 American Vacuum Society.