Role of Ge and Si substrates in higher-k tetragonal phase formation and interfacial properties in cyclical atomic layer deposition-anneal Hf1−xZrxO2/Al2O3 thin film stacks

Abstract

Using a five-step atomic layer deposition (ALD)-anneal (DADA) process, with 20 ALD cycles of metalorganic precursors followed by 40 s of rapid thermal annealing at 1073 K, we have developed highly crystalline Hf 1Àx Zr x O 2 (0 x 1) thin films (<7 nm) on $1 nm ALD Al 2 O 3 passivated Ge and Si substrates for applications in higher-k dielectric metal oxide semiconductor field effect transistors below 10 nm technology node. By applying synchrotron grazing incidence x-ray d-spacing maps, x-ray photoelectron spectroscopy (XPS), and angle-resolved XPS, we have identified a monoclinic to tetragonal phase transition with increasing ZrO 2 content, elucidated the role of the Ge vs Si substrates in complete tetragonal phase formation (CTPF), and determined the interfacial characteristics of these technologically relevant films. The ZrO 2 concentration required for CTPF is lower on Ge than on Si substrates (x $ 0.5 vs. x $ 0.86), which we attribute as arising from the growth of an ultra-thin layer of metal germanates between the Hf 1Àx Zr x O 2 and Al 2 O 3 /Ge, possibly during the first deposition and annealing cycle. Due to Ge-induced tetragonal phase stabilization, the interfacial metal germanates could act as a template for the subsequent preferential growth of the tetragonal Hf 1Àx Zr x O 2 phase following bottom-up crystallization during the DADA ALD process. We surmise that the interfacial metal germanate layer also function as a diffusion barrier limiting excessive Ge uptake into the dielectric film. An ALD Al 2 O 3 passivation layer of thickness !1.5 nm is required to minimize Ge diffusion for developing highly conformal and textured HfO 2 based higher-k dielectrics on Ge substrates using the DADA ALD process. Published by AIP Publishing.

On-Demand CMOS-Compatible Fabrication of Ultrathin Self-Aligned SiC Nanowire Arrays

“…The grazing incidence XRD (GIXRD) experiments were done at the Cornell High Energy Synchrotron Source (CHESS) using X-rays of energy 11.4 keV. The details of the experimental setup can be found elsewhere [ 41 ]. The vertical lines in the grazing incidence d-spacing map (GIDSM) confirmed the polycrystalline nature of the material.…”

Passivation of Ge surface treated with trimethylaluminum and investigation of electrical properties of HfTiO/Ge gate stacks

“…Compared with S1, the peaks of other samples shift to lower binding energy. It was reported that the introduction of Al2O3 passivation layer as well as TMA cleaning process can retard Ge outdiffusion and suppress the formation of GeOx and germanate [17,18,25,26] .…”

Optimizing the Ferroelectric Properties of Hf1–xZrxO2 Films via Crystal Orientation

“…In this study, angle-dependent X-ray photoelectron spectroscopy (AR-XPS) was used to probe the spatial distribution of O v within HZO. By changing the X-ray incident angle, , we can analyze the chemical state of each element in the HZO near the surface of the film (low X-ray angle) and inside the film (high X-ray angle). Figure a,b, respectively, presents the XPS spectra of the surface-Hf-4f and bulk Hf-4f in the RTA-standard sample.…”