Synthesis and characterization of titanium silicon oxide thin films prepared by plasma enhanced atomic layer deposition

Ternary alloys of titanium silicon oxide thin films having 149-192 angstrom in thickness were fabricated via the plasma enhanced atomic layer deposition (PEALD) process, and their characteristics were evaluated. The motivation of this study is applying these films to spacer materials for multiple patterning processes in semiconductor manufacturing. One titanium silicon oxide layer was formed via the combination of a typical PEALD sequence (precursor supply-purge-oxidation discharge-purge) for titanium oxides as well as that for silicon oxides. The ratio of these sequences, R-TiO/SiO, and the deposition temperature, T, were varied from 50 to 0.3 and from 100 to 400 degrees C to modify the film characteristics. The wet etching rate of the films greatly changes depending on R-TiO/SiO and T, indicating that the film characteristics are modified by tuning these parameters. The threshold value to avoid the crystallization of the films is R-TiO/SiO <= 3 according to the physical analyses such as x-ray diffraction and atomic force microscopy. The film variation confirmed in this study is well explained by the individual deposition temperature dependence of titanium oxides and silicon oxides; the former is the crystal grain formation in the films and the latter is the densification of the films for a high T. Published by the AVS.