Pulsed deposition of metal-oxide thin films using dual metal precursors

A technique for depositing high-dielectric-constant metal-oxide thin films is demonstrated that consists of alternating pulses of metal-chloride precursors and Hf(NO3)(4) in which Hf(NO3)(4) is used as an oxidizing agent as well as a metal source. The use of Hf(NO3)(4), rather than a separate oxidizing agent such as H2O, minimizes the potential for oxidation of the Si interface. Unlike HfCl4, a widely used precursor, the high reactivity of Hf(NO3)(4) initiates uniform deposition on H-terminated Si beginning with the first pulse. Effective dielectric constants obtained for HfO2 films produced by this method were comparable to HfO2 films deposited using other methods and the leakage current densities were three orders of magnitude less than SiO2 of the same equivalent thickness. Deposition of HfAlOx and HfZrOx ternary oxide films was also examined. The deposition rate for films produced using this method is greater than one monolayer per cycle, indicating a mechanism that is different from standard atomic-layer deposition. (C) 2004 American Institute of Physics.