EFFECT OF AN INCREASE IN THE NITROGEN-CONTENT OF THE WORKING GAS ON THE MICROSTRUCTURE OF REACTIVE SPUTTERED TIN THIN-FILMS

TiN films were deposited on (100)-Si substrates by RF-reactive sputtering. The effects of processing parameters and substrate orientation on the stoichiometry, resistivity and microstructure of reactively sputtered TiN thin films were investigated. The RF-power was fixed at 50 W, and the nitrogen content in the working gas was adjusted so that target nitridation occurred at a relatively low nitrogen content, 2.6% N2, in a fixed total flow rate of gases of 46.25 standard cubic centimetres (sccm). The N2 percentage was varied from 2.6% to 15.4%. The films were continuous and approximately 200 nm thick. Films deposited with the substrate facing the target exhibited 111-texturing, while films on substrates lying in the same plane of the target surface had 100-texturing. Both X-rays photoelectron spectroscopy and high-resolution detailed scans of the Auger electron energy spectrum were used for the stoichiometry determination. On the 100-textured TiN films, the N/Ti ratio was approximately 1.0 at low N2 flow rates; the N/Ti ratio rapidly increased with N2 flow rate, and then levelled off. The films had resistivities ranging from 85 to 1340-mu-OMEGA-cm, and the functional dependence of both N/Ti and the resistivity values behaved similarly with increasing N2. X-ray single-line profile analysis of the 200-reflection indicated that the average crystallite size decreased and the average strain increased with increasing nitrogen content in the working gas. The Si/TiN structures were heat treated in the temperature range from 300 to 600-degrees-C in a quartz tube under 1 atm (approximately 10(5) Pa) of flowing high purity Ar gas. Heat treatment at 300-degrees-C did not affect the TiN film integrity, while treatment at 400-600-degrees-C resulted in void-type defects.