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

Abstract

AbstractThe 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.