Influence of the sputtering gas on the preferred orientation of nanocrystalline titanium nitride thin films

Abstract

Nanocrystalline titanium nitride thin films have been deposited by high pressure reactive magnetron sputtering from an elemental titanium target using a mixture of an inert gas and nitrogen. The mean crystallite or grain size in these films is in the range 8–12 nm as measured from X-ray line broadening. Interestingly, the type of inert gas used in the sputtering gas mixture significantly influences the microstructure and preferred orientation in these films. Thus, using a 70% He+30% N 2 gas mixture results in a strongly (002) oriented film whereas using a 70% Ar+30% N 2 gas mixture results in a strongly (111) oriented film with a similar grain size. In addition, films have also been deposited using pure nitrogen as the sputtering gas. These films exhibited a strong (002) orientation and had a significantly larger grain size as compared with those deposited using a mixture of an inert gas and nitrogen. Details of the microstructure in these films have been investigated by transmission electron microscopy. The ability to tailor the size and preferred orientation of grains in the TiN thin films (by proper choice of sputtering gas) is expected to have a significant impact on the properties of these films in a variety of technological applications.