Determination of optical constant and electrical properties of sputtering-derived HfTiON gate dielectrics

Nitrogen content dependent optical constant and electrical properties of sputtering-derived HfTiON gate dielectrics on Si substrate have been investigated. By means of characterization of ultraviolet-visible spectroscopy, reduction in band gap of HfTiON film has been detected with the increase in nitrogen concentration. Electrical measurements of MOS capacitor based on Al/HfTiON/Si gate stacks have indicated that a low interface-state density with almost ignorable frequency dispersion at applied gate voltage of 1 V have been obtained for all samples. With increasing the nitrogen concentration, the improved electrical performance has been observed. For the sample with Ar/N2 flow ratio of 20/5, rapid thermal annealing (RTA) treatment at 200 °C achieves relatively favorable excellent electrical properties in terms of low gate leakage current density and oxide charge density (Qox). The conduction mechanism for 200 °C-annealed sample has been analyzed systematically.