Initial growth and texture formation during reactive magnetron sputtering of TiN on Si(111)

Abstract

The initial growth and texture formation mechanism of titanium nitride (TiN) films were investigated by depositing TiN films on (111) silicon substrates by using reactive magnetron sputtering of a Ti metallic target under a N2/Ar atmosphere, and then analyzing the films in detail by using transmission electron microscopy (TEM) and x-ray diffraction (XRD). Two power sources for the sputtering, dc and rf, were compared. At the initial growth stage, a continuous amorphous film containing randomly oriented nuclei was observed when the film thickness was about 3 nm. The nuclei grew and formed a polycrystalline layer when the film thickness was about 6 nm. As the film grew further, its orientation changed depending on the deposition conditions. For dc sputtering, the appearance of (111) or (200)-preferred orientations depended on the N2 partial pressure, and the intensity of the preferred orientation increased with increasing film thickness. For rf sputtering, however, when the film thickness was small (for instance, about 20 nm), the film showed (200) orientation, independent of the N2 partial pressure, and further growth caused the film to orient to the (111) orientation when the N2 partial pressure was low (about 0.015 Pa). The results indicated that preferred orientation of TiN films is controlled by a competition between kinetic and thermodynamic effects.