Ionized magnetron sputter deposition of amorphous carbon nitride thin films

Carbon nitride thin films were prepared using an ionized magnetron sputtering system. An inductively coupled rf plasma was generated in the region between the sputtering source (high purity graphite) and the substrate table. An argon-nitrogen mixture was used as the sputtering gas. Sputtered atoms which pass through the radio frequency (rf) plasma may be ionized, and the degree of ionization depends on several processing variables, such as the gas total pressure, reactive gas partial pressure, and applied rf power. Pulsed substrate bias voltage was varied up to -500 V. Chemical bonding and composition of the deposited films were studied by infrared and Auger electron spectroscopy, respectively. An ultramicroindentation system was used to measure the hardness. Nitrogen was found to be bonded to carbon in various configurations. The dependence of the nitrogen-to-carbon ratio and film hardness on the deposition conditions was studied. Under optimum conditions, films with nitrogen-to-carbon ratio —0.3-0.4 and hardness up to 16–17 GPa were made. These values are similar to those obtained without the rf plasma. There is no correlation between the film hardness and the nitrogen-to-carbon ratio.