Effects of the oxygen precursor on the electrical and structural properties of HfO 2 films grown by atomic layer deposition on Ge

Abstract

We report on the growth by atomic layer deposition of Hf O2 films on HF-last treated Ge(001) substrates using Hf Cl4 as a Hf source and either O3 or H2 O as oxygen sources. The choice of the oxygen precursor strongly influences the structural, chemical, and electrical properties of the Hf O2 films: Those grown using H2 O exhibit local epitaxial growth, a large amount of contaminants such as chlorine and carbon, and a large frequency dispersion of the capacitance-voltage (C-V) characteristics. Films grown using O3 are good insulators and exhibit well-shaped C-V curves with a minimum frequency dispersion of the accumulation capacitance. Moreover, they are smoother, less crystallized, and with a lower contaminant content than those grown using H2 O. However, the use of O3 leads to the formation of a 2 nm thick layer, possibly Ge Ox, at the Hf O2 Ge interface. © 2005 American Institute of Physics.