Ultraviolet-ozone oxidation of metal films

Metal oxides such as zirconia and hafnia are being investigated as new materials for application as gate dielectrics in future complementary metal-oxide-semiconductor devices. In this paper, we present results on oxidation of metal films such as Zr, Hf, and Al by the ultraviolet (UV) ozone oxidation method. A nuclear reaction analysis technique, the 16O(d,*a)14N nuclear reaction, was used to quantify the oxygen concentration in the dielectric stacks. The method was found to be sensitive to monolayer levels of oxygen. It was found that the oxidation kinetics of the metals increased significantly due to the presence of UV light. The oxidation rate was also found to depend on the oxygen partial pressure. The oxidation rate of Zr was greater than that of Hf, while Al oxidized more slowly than Hf for the UV-ozone oxidation conditions investigated. Possible reasons for the observed oxidation behavior are discussed in detail.