Nucleation engineering for atomic layer deposition of uniform sub-10 nm high-K dielectrics on MoTe_2

摘要

Continuous, uniform, and sub-10 nm Al2O3 high-K dielectrics upon two-dimensional exfoliated multilayer MoTe2 are realized by atomic layer deposition (ALD) based on a nucleation layer (NL) prepared by the ozone-based process, interfacial AlN, and low-temperature (low-T) physical adsorption. The NLs gives rise to significant reduction of the leakage current in the sub-10 nm Al2O3 high-K dielectrics as shown by conductive atomic force microscopy. For the ozone-based NL, X-ray photoelectron spectroscopy (XPS) reveals the oxidation of MoTe2 which is detrimental to the electrical properties of MoTe2. For the AlN NL, XPS reveals that Mo-N bonds were formed without Mo-O bonds and no chemical shift appeared in Te-3d XPS spectrum, indicating the AlN NL did not result in the MoTe2 oxidation but instead the formation of an MoN layer. For the low-T NL, the XPS spectra of MoTe2 are the same as those of the as-exfoliated MoTe2 flake, consistent with the absence of chemical reactions during low-T physical adsorption. The result demonstrates that the NLs prepared by the low-T physical adsorption and the interfacial AlN are effective and favorable for nucleating high-quality high-K gate dielectrics on MoTe2 transistors.