Substrate Biasing during Plasma-Assisted ALD for Crystalline Phase-Control of TiO2 Thin Films

Substrate biasing has been implemented in a remote plasma atomic layer deposition (ALD) reactor, enabling control of the ion energy up to 260 eV. For TiO 2 films deposited from Ti(Cp Me )(NMe 2 ) 3 and O 2 plasma it is demonstrated that the crystalline phase can be tailored by tuning the ion energy. Rutile TiO 2 was obtained at 200 and 300°C, typically yielding amorphous and anatase films without biasing. Aspects such as film mass density, [O]/[Ti] ratio and growth per cycle under biased conditions are addressed. The results demonstrate that substrate biasing is a viable method for ALD to tailor ultra-thin film properties.