Interface Optimization and Temperature Reliability Estimation of Er<i>ₓ</i>Y<i>y</i>O/Si Gate Stacks by ALD-Derived AlN Passivation Layer

A detailed investigation into the effects of atomic layer deposition (ALD)-derived AlN passivation layer on the interface chemistry, temperature stability, and leakage current conduction mechanism (LCCM) of ErxYyO/Si gate stacks has been carried out in this work. The findings have indicated that ALD-driven AlN passivation layer significantly suppresses the diffusion of substrate elements, thereby enhancing the quality of the interface. X-ray photoelectron spectroscopy (XPS) analysis revealed that the low valence oxides of silicon decrease with the increase of the passivation period, thus improving the interface state. Electrical characterizations demonstrated that the samples treated with 40 cycles of passivation exhibited the best electrical properties, including a high dielectric constant (17.69) and a low leakage current density of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$7.16\times 10^{-{8}}$ </tex-math></inline-formula> A/cm2. The interfacial state density, as determined by the conductivity method, indicated that the passivation treatment was effective in controlling the interfacial quality, demonstrating the lowest interfacial state density (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.79\times 10^{{12}}$ </tex-math></inline-formula> eV<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-{1}}\cdot $ </tex-math></inline-formula> cm−2) observed for the S2 sample. Temperature stability studies have demonstrated that high temperature leads to the decrease device stability, which can be mitigated by the AlN passivation layer. LCCM analysis has revealed that Schottky emission (SE) dominates at low electric fields, while Poole-Frenkel (PF) emission dominates at medium to high electric fields, and Fowler-Nordheim (FN) tunneling is exhibited at high electric fields. These findings suggest that the ErxYyO gate dielectric treated with AlN passivation layer exhibits excellent electrical properties and improved interface quality. Consequently, ALD-processed AlN may be a promising candidate for the passivation layer of metal-oxide–semiconductor (MOS) devices in the future.