Investigation of TiN/LaO x Interface Dipole Effect on Negative Flat-Band Voltage ( V FB ) Shift in TiN/LaO x /HfO 2 /SiO 2 Gate Stacks Using Dipole-Last Technology

作者：Yu Wang, Jiaxin Yao, Yanzhao Wei, Qingzhu Zhang, Nannan You, Shuai Yang, Huaxiang Yin · 发表于：IEEE Transactions on Electron Devices · 年份：2025 · DOI：10.1109/ted.2025.3614523 · 被引用次数：4 · 研究领域：Semiconductor materials and devices、Integrated Circuits and Semiconductor Failure Analysis、Advancements in Semiconductor Devices and Circuit Design

In this study, the effect of the TiN/LaOxinterface dipole on the negative flat-band voltage (${V}_{\text {FB}}$) shift in TiN/LaOx/HfO2/SiO2gate stacks using La dipole-last technology was investigated. The experimental results demonstrated that the La dipole-last drive-in and removal (D&R) process enabled${V}_{\text {FB}}$modulation of −171 mV, with the D&R process itself accounting for −123-mV shift. Due to the high thermal budget, although the LaOxdipole layer suppressed the increase in trap/detrap electron density (${N}_{\text {ot}}$), it also led to an increase in equivalent oxide thickness (EOT), interface trap density (${D}_{\text {it}}$), and gate leakage current. Furthermore, high-resolution transmission electron microscopy (HRTEM) and X-ray photoemission spectroscopy (XPS) analyses revealed that La did not diffuse to the high-$_{\kappa}$/SiO2interfacial layer (IL) to form La–O–Si bonds. Instead, the detected La–N bonds indicated that interface dipole formation at the TiN/LaOxinterface was responsible for the negative${V}_{\text {FB}}$modulation. Based on these experimental findings, a TiN/LaOxinterface dipole mechanism was proposed and subsequently validated through the fabrication and characterization of a La laminate stack using the La dipole-last laminate process. These findings provide insights into the${V}_{\text {FB}}$tuning mechanism of the La dipole-last technology in HfO2high-$_{\kappa}$dielectric layers.