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 TiO2 films deposited from Ti(CpMe)(NMe2)3 and O2 plasma it is demonstrated that the crystalline phase can be tailored by tuning the ion energy. Rutile TiO2 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.