Effects of substrate heating and biasing on nanostructural evolution of nonepitaxially grown TiN nanofilms

Abstract

The effects of substrate heating and substrate biasing on the initial stage of nonepitaxial heterogeneous growth of TiN on Si(111) was studied by using high-resolution transmission electron microscopy. Although TiN films deposited at room temperature (RT) undergo a transition from continuous amorphous films to polycrystalline films with three-dimensional grains when the film thickness is increased from ∼1 to 2 nm, crystallization occurred at a substrate temperature, Ts=570 K, even for film thicknesses less than 1 nm. Compared with growth at Ts=RT, at Ts=570 K, the initial lateral grain size was only slightly larger, and the grains tended to be spherical and discontinuous at higher film thickness. At a substrate bias voltage, Vb=−70 V, the grains were laterally larger and planar. At a film thickness of 50 nm, the films deposited at Vb=−70 V showed the thermodynamically favored (200) preferred orientation, whereas the films deposited at Ts=570 K showed (111) preferred orientation with a weak (200) peak.