Towards Epitaxial Ferroelectric HZO on n+-Si/Ge Substrates Achieving Record 2Pr= 84 μC/cm2and Endurance > 1E11
Journal
Digest of Technical Papers - Symposium on VLSI Technology
Journal Volume
2023-June
ISBN
9784863488069
Date Issued
2023-01-01
Author(s)
Zhao, Zefu
Chen, Yu Rui
Chen, Yun Wen
Hsieh, Wan Hsuan
Wang, Jer Fu
Lee, Jia Yang
Xing, Yifan
Chen, Guan Hua
Abstract
Nearly epitaxially grown ferroelectric Hf0.5 Zr0.5 O2 (HZO) films on (001) n+-Si(3E19/cm 3) and n+ -Ge(3E20/cm 3) substrates exhibit record remanent polarization (2P r) of 84 and 73μC/cm2, respectively, which are higher than that on amorphous SiO2 (α-SiO2) and partially crystallized TiN underlayers. HZO films on n+ -Si and n+-Ge also show high coercive field (2Ec) of 8.8 and 5.8 MV/cm, respectively. Superlattice HZO films by plasma-enhanced atomic layer deposition (PEALD) show that c-axis is well-aligned with the growth direction in scanning transmission electron microscopy (STEM) images, consistent with observed high 2Pr of epitaxial HZO films on n+-Si(Ge). The density functional theory (DFT) indicates o-phase is greatly stabilized in the HZO films on n+- Si(Ge) substrates due to low interfacial energy at o-phase/Si(Ge) interfaces as compared to m-(t-)phase/Si(Ge). After 1E9 and 1E11 endurance cycles, the HZO on n+-Si and n+-Ge substrates have record finial 2P r of 51 and 47 μC/cm2, respectively. Our study demonstrates the way to achieve single crystalline ferroelectric HZO films by using small misfit substrates without interfacial layers. The thermal budget is as low as 450°C.
Type
conference paper