| Aluminum nitride thin films have been deposited by pulsed DC reactive magnetron sputtering. The pulsed DC power provides arc-free deposition of insulating films. Two types of pulsed DC (unipolar and asymmetric bipolar) were studied with respect to characteristics and properties of resultant films. The crystal structure of the AlN films was examined by XRD. The microstructures of the AlN films were observed by SEM and AFM. The control of crystal orientation of deposited film is important since the properties of AlN film is related with the orientation. For example, the acoustic velocity is high along the c-axis. The electromechanical coupling coefficient is large in a-axis direction.{09}The crystal orientation and microstructure of the AlN films were strongly affected by the deposition conditions such as sputtering power, growth temperature, sputtering gas pressure and frequency/duty cycle. The crystal orientation of AlN films was closely related with the energy of sputtered atoms and mobility of adatoms on substrate. The c-axis oriented films were obtained when energy of sputtered atoms and mobility were high.; MIM structure was fabricated to measure dielectric properties of AlN films. Dielectric constants of 8.5 to 11.5 were obtained at 100 kHz. The thermal conductivity of AlN films was in the range of 12 and 30 W/mK, which is very low when compared with those of bulk. This might be attributed to the oxygen related defects, which is confirmed by photoluminescence analysis.; The plasma parameters such as electron temperature and charge density were obtained by the Lagmuir probe. The electron temperature in argon and nitrogen plasma increased from 2.7 to 5.3 eV as increasing frequency. The charge densities were found to increase with frequency. The measured plasma characteristics were correlated with properties of the AlN film. The ion and energy flux were believed to increased as the frequency increased. The intensity of the (002) peaks was found to increase with the increase in the ion flux and energy flux. |
