GROWTH OF TIN FILMS ON (001) NACL BY RF REACTIVE SPUTTERING

TiN films have wide-ranging applications from erosion resistant coatings for cutting tools to diffusion barriers in LSI devices. The purpose of this work is to investigate the growth process of reactive sputtered TiN films. TiN(x) films were deposited onto air cleaved (001)NaCl single crystals by rf sputtering of 99.9% Ti disk (70 mm in diameter) with Ar + N2 mixed gas. Total gas pressure during sputtering (P(total)) was 0.4 Pa. The N2 partial pressure-to-total pressure ratio (P(N2)/P(total)), substrate temperature (T(sub)) and rf power (P(rf)) were changed 0.0-0.5, R. T. is similar to 300-degrees-C and 100-300 W, respectively. The microstructure of the films was studied by transmission electron microscopy. A deposition rate decreased with increasing P(N2)/P(total) and decreased drastically when P(N2)/P(total) increased above a threshold value. The threshold value was about 0.25 at P(rf) 300 W. It was shown that the films prepared at above the threshold value were gold colored and had TiN structure. Although a microstructure was constructed by fine grains, the gold colored film showed strong preferred orientation, which was (001) TiN//(001) NaCl. The higher substrate temperature and the higher applied rf power resulted in the larger grain sized film. It was considered that growth process of TiN films was based on a three dimensional nucleation. Unfortunately, reproducibility was not so good, it was suggested that (001)TiN single crystal films were able to grow on (001)NaCl at 300-degrees-C, which was lower than the reported epitaxial temperature of TiN films on MgO single crystal.