硅酸盐学报2025，Vol.53Issue(9)：2430-2440,11.DOI:10.14062/j.issn.0454-5648.20250236
界面效应对铝掺杂氧化铪铁电薄膜极化翻转特性的影响
Influence of Interface Effects on Polarization Switching Characteristics of Al-Doped Hafnium Oxide Ferroelectric Films
摘要
Abstract
Introduction Hafnium oxide-based ferroelectric memory has become a research hotspot due to its compatibility with CMOS processes,low power consumption,and inverse size effect.Memory technology has transitioned from 2D planar to 3D vertical stacking,enabling the stacking of multiple memory cells.The gate first process of 3D NAND architecture requires the ferroelectric layer to withstand high annealing temperature.Al-doped hafnium oxide films can endure annealing at 700-1000℃,meeting the process requirements.Florent et al.first demonstrated a 3D NAND device based on Al:HfO2,achieving a 2Pr value of 17 μC/cm² after annealing at 850℃,showcasing its potential in non-volatile memory applications.As devices trend toward miniaturization and integration,reducing the thickness of the ferroelectric layer is key to achieving high-density stacking and lowering power consumption.When the thickness is scaled down to the nanoscale,interface effects become significant.Studies show that an interfacial oxide layer forms between the ferroelectric film and the metal electrode,leading to the accumulation of oxygen vacancies,the generation of a built-in electric field,and polarization asymmetry.To understand interface effects,it is essential to study them from the perspective of polarization switching.This work focuses on Hf1-xAlxO2 films to investigate the influence of interfaces on polarization switching behavior.The study reveals that the interfacial layer between the ferroelectric layer and the metal electrode hinders polarization switching in the programmed state. Methods First,a 40 nm tungsten(W)bottom electrode was deposited on a p+-Si substrate at room temperature using magnetron sputtering.Subsequently,Al-doped HfO2(HAO)ferroelectric films with thicknesses of 6.8 nm,15.8 nm,and 20.4 nm were prepared by atomic layer deposition(ALD)at a deposition temperature of 295℃.Tetrakis(ethylamido)hafnium(TEMA-Hf),trimethylaluminum(TMA-Al),and water(H2O)were used as the hafnium source,aluminum source,and oxygen source precursors,respectively.The cycle ratio of aluminum to hafnium deposition was 1:29.Total cycles for HAO films with thicknesses of 6.8,15.8 nm and 20.4 nm are 90,210 and 270,respectively.Then,a 40 nm W top electrode was deposited using magnetron sputtering,resulting in W/HAO/W capacitor structures.Finally,the two capacitor structures were subjected to rapid thermal annealing at 700℃for 30 s in a nitrogen atmosphere. Results and discussion The 6.8 nm,15.8 nm,and 20.4 nm HAO films fabricated on W electrodes exhibited remanent polarization(2Pr)values of 38.8,43.2 μC/cm² and 37.6 μC/cm² after waking up,demonstrating excellent ferroelectric properties.During the fabrication of 6.8 nm HAO films,interfacial WOx layers with thicknesses of 0.5 nm and 1.8 nm were formed.Based on this observation,ERS and PRG polarization switching behaviors were designed to investigate interfacial effects on switching dynamics.Under an electric field of 1.8 MV/cm,the divergence in switching time between these two states amplifies with HAO film thickness scaling.Polarization switching in PRG state of 6.8 nm HAO film is hindered by the built-in electric field,exhibiting ∆P/2PS significantly below 1,whereas ERS state achieves near-complete switching(∆P/2PS is about 1)with substantially faster kinetics.Comparative analysis of COD values from NLS model and KAI model fittings reveals:For ERS state,both models yield COD>0.9,indicating comparable timescales for domain nucleation and growth.In contrast,PRG state polarization switching behaviors at 1.8 MV/cm requires exclusive description by the NLS model,demonstrating nucleation-limited behavior under low fields.With increasing electric field,decreasing COD values for NLS fittings and increasing COD values for KAI fittings suggest a gradual transition from nucleation-dominated to growth-dominated switching mechanisms in ERS and PRG states. Conclusions This paper prepared HAO ferroelectric films with three thicknesses(6.8,15.8 nm,and 20.4 nm)via ALD,and investigated the influence of interface effects on polarization switching characteristics by comparing differences in polarization switching behavior between ERS and PRG states.The results indicate that the divergence in polarization switching time between ERS and PRG states increases with HAO film thickness scaling,attributed to the thicker interfacial oxide layer at the bottom interface compared to the top interface.This asymmetry leads to higher oxygen vacancy concentration at the bottom interface,generating a built-in electric field directed from the film toward the top electrode.As HAO film thickness decreases,the proportion of interfacial oxide layers increases,amplifying the built-in electric field that hinders polarization switching in PRG state.For the 6.8 nm HAO film under ERS state,the COD values fitted by both NLS and KAI models exceed 0.9,indicating comparable timescales for domain nucleation and growth.However,in PRG state at 1.8 MV/cm,the ∆P/2PS is significantly below 1.,requiring description by the NLS model.With increasing electric field,the ∆P/2PS progressively rises to 1(Complete polarization reversal),accompanied by a transition from NLS to KAI model behavior.This arises because the built-in electric field impedes polarization switching in PRG state,necessitating additional energy to overcome nucleation barriers.Under high electric fields,sufficient energy is provided to surmount interfacial domain nucleation barriers,significantly enhancing PRG domain nucleation rate and accelerating polarization switching dynamics.关键词
界面效应/铝掺杂氧化铪铁电薄膜/极化翻转Key words
interface effects/aluminum doped hafnium oxide ferroelectric thin films/polarization switching分类
通用工业技术引用本文复制引用
范宇昕,贾世杰,廖佳佳,周益春..界面效应对铝掺杂氧化铪铁电薄膜极化翻转特性的影响[J].硅酸盐学报,2025,53(9):2430-2440,11.基金项目
国家自然科学基金(12302429). （12302429）
