Atomic Layer Deposition of HfO2 Thin Films Employing a Heteroleptic Hafnium Precursor


  • The authors from RUB gratefully acknowledge the German Research Foundation (DFG) for funding this project (DFG-DE-790-9-1) as well as Prof. R. A. Fischer for his continuous support. KX expresses his appreciation to the RUB-Research School for granting a PhD research fellowship.


The application of a heteroleptic hafnium amide-guanidinate precursor for the deposition of HfO2 thin films via a water-assisted atomic layer deposition (ALD) process is demonstrated for the first time. HfO2 films are grown in the temperature range 100–300 °C using the compound [Hf(NMe2)2(NMe2-Guan)2] (1). This compound shows self-limiting ALD-type growth characteristics with growth rates of the order of 1.0–1.2 Å per cycle in the temperature range 100–225 °C. The saturation behavior and a linear dependence on film thickness as a function of number of cycles are verified at various temperatures within the ALD window. The as-deposited HfO2 films are characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM), Rutherford backscattering spectroscopy (RBS), X-ray photoelectron spectroscopy (XPS), and electrical measurements. For a direct comparison of the precursor performance with that of the parent alkyl amide [Hf(NMe2)4] (2), ALD experiments are also performed employing compound 2 under similar process conditions, and in this case no typical ALD characteristics are observed.