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

摘要

A technique for depositing high-dielectric-constant metal-oxide thin films is demonstrated that consists of alternating pulses of metal-chloride precursors and Hf(NO_3)_4 in which Hf(NO_3)_4 is used as an oxidizing agent as well as a metal source. The use of Hf(NO_3)_4, rather than a separate oxidizing agent such as H_2O, minimizes the potential for oxidation of the Si interface. Unlike HfCl_4, a widely used precursor, the high reactivity of Hf(NO_3)_4 initiates uniform deposition on H-terminated Si beginning with the first pulse. Effective dielectric constants obtained for HfO_2 films produced by this method were comparable to HfO_2 films deposited using other methods and the leakage current densities were three orders of magnitude less than SiO_2 of the same equivalent thickness. Deposition of HfAlO_x and HfZrO_x 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.