The Quality Improvement of Yttrium Oxide Thin Films Grown at Low Temperature via the Third‐Generation Mist Chemical Vapor Deposition Using Oxygen‐Supporting Sources
Li Liu, Toshiyuki Kawaharamura, Masahito Sakamoto, Misaki Nishi, Giang T. Dang, Shota Sato
Abstract
Yttrium oxide (Y 2 O 3 ) thin films are deposited by the third‐generation mist chemical vapor deposition (CVD) system. To avoid high growth temperature, H 2 O and O 2 , as oxygen sources, are selected to support the fabrication process. The Y 2 O 3 films are prepared under different oxygen‐source supporting conditions to obtain high‐quality thin films; the effects of H 2 O and O 2 on the film properties are also investigated to confirm the formation processes of Y 2 O 3 films fabricated by mist CVD. Y 2 O 3 films with a deposition rate of 9.0 nm min −1 , refractive index of 1.76, and dielectric constant ranging from 15 to 20 are obtained at 400 °C when H 2 O is used to support the fabrication. Thermogravimetry–differential thermal analysis of the yttrium precursor Y(C 5 H 7 O 2 ) 3 · n H 2 O is conducted using air and air+H 2 O mist as carrier gas. The analysis confirms that H 2 O supporting can lower the growth temperature and improve the film quality by reducing the formation temperature of main products in the process of obtaining Y 2 O 3 . Moreover, the H 2 O and O 2 used in the fabrication are in liquid and gas phases, respectively. Consequently, the supporting processes of H 2 O and O 2 occur at different time and space inside the reactor, which results in different supporting effects.