New Precursors for the CVD of Zirconium and Hafnium Oxide Films

Abstract

Alternatives to tetrakis(dialkylamido)zirconium and hafnium for use as precursors to zirconium and hafnium oxide films are examined. Tetrakis(trimethylhydrazido)zirconium and hafnium, Zr(NMeNMe2)4 and Hf(NMeNMe2)4, and Hf[tBuNCH2CH2N-tBu]2 are used with oxygen as precursors to zirconium and hafnium oxide films in a low-pressure CVD process at substrate temperatures <400 °C. The as-deposited films are amorphous, featureless, and transparent on glass. X-ray photoelectron spectroscopy (XPS) data shows that the films deposited using the hydrazido complexes and oxygen as precursors are carbon- and nitrogen-free, while the films obtained from Hf[tBuNCH2CH2N-tBu]2 and oxygen have a composition HfO1.6C0.06N0.2. A thin (<1500 Å) zirconium oxide film remains amorphous after annealing for 2 h at 950 °C. The X-ray crystal structure of Hf[tBuNCH2CH2N-tBu]2, which was synthesized along with its Zr congener from MCl4 and Li2[tBuNCH2CH2N-tBu], reveals that it has an elongated tetrahedral geometry in the solid state.