Interfacial Layer Engineering in Sub-5-nm HZO: Enabling Low-Temperature Process, Low-Voltage Operation, and High Robustness

Abstract

For low-voltage reliable operation of ferroelectric devices, the scaling of Hf <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{1}-\textit{x}}$</tex-math> </inline-formula> Zr <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\textit{x}}$</tex-math> </inline-formula> O <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$_{\text{2}}$</tex-math> </inline-formula> (HZO) thickness ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{t}_{\text{HZO}}$</tex-math> </inline-formula> ) is important. Despite the importance of scaling, ferroelectricity degradation and increased process thermal budget hinder progress. In this work, we propose the use of an interfacial layer (IL) to mitigate these scaling issues and validate its effectiveness in thin <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\textit{t}_{\text{HZO}}$</tex-math> </inline-formula> . Our findings demonstrate that IL can activate ferroelectricity below the critical temperature of ferroelectric HZO. Moreover, we report 2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> polarization improvement, reduced operation voltage from 1.5 to 1.2 V, and substantially improved endurance with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt;$</tex-math> </inline-formula> 10 years of reliability, all based on experimental results. We believe this systematic work offers a simple yet efficient route toward HZO scaling in ferroelectric devices.