Correlation of electrical and morphological properties of sputtered aluminum nitride films with deposition temperature

The present work reports on the little explored correlation of electrical properties in conjunction with morphology of RF sputtered aluminum nitride (AlN) films at different substrate temperatures (100 °C –400 °C). Electrical properties, especially insulator charge density (Qin) and interface state density (Dit) were studied by using Al/AlN/Si (MIS) as a test vehicle. X-ray diffraction, FTIR spectroscopy, AFM and SEM techniques were studied for crystal orientation, bond formation, surface roughness and grain size of AlN film, respectively. Relatively highly c-axis (0 0 2) oriented films were found in between 200 °C and 300 °C with FTIR absorption peak at 682 cm−1. Decrease in Qin from 7.9 × 1011 cm−2 to 1.0 × 1011 cm−2 found to be associated with increase in surface roughness and grain size, with temperature. There is no significant change in interface state density with deposition temperature. It is found that better crystallinity results in a good dielectric constant.