Effects of the oxygen precursor on the electrical and structural properties of HfO2 films grown by atomic layer deposition on Ge -: art. no. 112904

We report on the growth by atomic layer deposition of HfO2 films on HF-last treated Ge(001) substrates using HfCl4 as a Hf source and either O-3 or H2O as oxygen sources. The choice of the oxygen precursor strongly influences the structural, chemical, and electrical properties of the HfO2 films: Those grown using H2O 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 O-3 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 H2O. However, the use of O-3 leads to the formation of a 2 nm thick layer, possibly GeOx, at the HfO2/Ge interface. (c) 2005 American Institute of Physics.