Atomic Layer Deposition of Gd-Doped HfO[sub 2] Thin Films

Abstract

GdxHf1−xnormalOy thin films were deposited by atomic layer deposition (ALD) using tris(isopropyl-cyclopentadienyl) gadolinium [Gd(normalPirCp)3] and HfCl4 in combination with normalH2O as an oxidizer. Growth curves showed a nearly ideal ALD behavior. The growth per individual Gd(normalPirCp)3/normalH2O or HfCl4/normalH2O cycle was 0.55 Å, independent of the Gd/(Gd+Hf) composition x in the studied range. This indicates that the amount of HfO2 deposited during a HfCl4/normalH2O cycle was essentially identical to the amount of Gd2normalO3 deposited during a Gd(normalPirCp)3/normalH2O cycle, assuming identical atomic densities of the films independent of composition. The crystallization of GdxHf1−xnormalOy with Gd/(Gd+Hf) contents x between 7 and 30% was studied. Films with x≳10% crystallized into a cubic/tetragonal HfO2 -like phase during spike or laser annealing up to 1300°C , demonstrating that the cubic/tetragonal phase is thermally stable in this temperature range. A maximum dielectric constant of κ∼36 was found for a Gd/(Gd+Hf) concentration of x∼11% .

NiO Thin Films Synthesized by Atomic Layer Deposition using Ni(dmamb)2 and Ozone as Precursors

“…[49][50][51] A close look at the spectra in the region 1300-1750 cm (5) and (6), observed for ALD films deposited at 140 8C, can be attributed to entrapped CO 2 and carboxylate or formate groups. The commonly observed bands (7), (8), and (9) for the films prepared by both methods corresponds to bridged, organic-like or monoand bidendate structures from CO and CO 2 adsorption.…”

Novel high-κ dielectrics for next-generation electronic devices screened by automated ab initio calculations

“…The large energy difference implies that c-BeO would be difficult to stabilize under ambient conditions. However, we pay attention to the experiments in Adelmann et al 25 , Kita et al 26 and Tsipas et al 27 , which indicate that the high-temperature phases of HfO 2 and ZrO 2 can be synthesized as thin films by external doping or strain. More importantly, the doped phases possessed increased dielectric constants, as predicted by theory.…”

On the structural origins of ferroelectricity in HfO2 thin films

“…Here, we focus on the lower symmetry phases of HfO 2 , i.e., monoclinic and orthorhombic, as the two higher symmetry phases Fm 3m and P4 2 nmc are paraelectric. 1, 18,19 Due to consistencies with the related ZrO 2 system, the Pca2 1 orthorhombic structure is primarily thought to be the cause of ferroelectricity in HfO 2 , but this has not been unambiguously confirmed by experiment. 10 While grazing incidence x-ray diffraction (GIXRD) experiments point to the existence of an orthorhombic phase, the analysis of the patterns is complicated due to the mixture of different phases in the film, similarities between the respective reference patterns of the potential HfO 2 phases, and severe peak broadening of polycrystalline thin films, as shown in Figure 1(b).…”