Titanium Hafnium Oxide Alloy Films by a Novel Sub-Atomic Layer Sputtering Process for High Index and Graded Index Applications

Abstract

ABSTRACTWe studied physical properties of titanium hafnium oxide (TixHf1-xO2) alloy thin films deposited by pulsed DC reactive magnetron sputtering with AC substrate bias. Thin films of two end oxides, hafnium oxides (HfO2) and titanium oxides (TiO2), and their alloys TixHf1-xO2 with a range of compositions deposited with and without the substrate bias were compared to study the dependence of physical properties of the thin films on the substrate bias. Structural, chemical and optical properties of the thin films were analyzed to assess inter-relationship among these properties. Thin films deposited with the AC substrate bias consistently show much higher refractive index and significantly lower optical extinction coefficient than those of thin films deposited without the substrate bias suggesting that characteristic microstructures developed in these thin films are responsible for the differences in the optical properties.