Atomic Layer Deposition of HfO2 onto Si Using Hf(NMe2)4

The temperature window for the atomic layer deposition (ALD) of HfO2 onto Si using Hf(NMe2)(4) [tetrakis(dimethylamino)hafnium] as an Hf precursor was determined based on the thermal decomposition characteristics of Hf(NMe2)(4), as observed by temperature-programmed decomposition in an ultra-high vacuum. The growth rate of the HfO2 obtained in the temperature window was ca. 1.2 angstrom/cycle. The prepared film had electrical properties suitable for use in complementary metal-oxide-semiconductor (CMOS) devices, showing an equivalent-oxide thickness (EOT) of 2.5 nm and a leakage current density of 1.3 x 10(-6) A/cm(2) at -1 V. The leakage current was three orders of magnitude lower than that of SiO2 with the same EOT. The lower current leakage was obtained because N atoms in the Hf(NMe2)(4) formed an SiNx interlayer by reaction with the Si substrate during the ALD, as confirmed by in-situ X-ray photoelectron spectroscopy (XPS) and by the analysis of residue on the substrate after the decomposition of the Hf precursor. (C) 2009 The Japan Society of Applied Physics