原子层沉积的TiN/HZO堆栈界面元素的扩散研究

Diffusion of Interfacial Elements in TiN/HZO Stacks Deposited by Atomic Layer

传统钙钛矿材料微缩后难以保存铁电性,并且与CMOS的兼容性差,而薄至10 nm以内的铪锆氧化物(HZO)材料仍然具有铁电性且与CMOS兼容性好,这弥补了传统钙钛矿的本征短板,备受学界和产业界关注,有望替代动态随机存储器应用于非易失性铁电存储器(FERAM)和铁电晶体管基集成电路中。基于目前应用最广泛的TiN/HZO/TiN堆栈,采用具有高端应用前景的原位ALD技术生长TiN电极,很好地控制了电极层的生长速度及其纳米级的膜厚。研究了堆栈界面元素扩散问题,通过飞行时间二次离子质谱技术发现了界面元素的外扩散现象,采用角分辨X射线光电子能谱研究了外扩散行为的机制,提出了一个可能的理论解释,即由于TiN和HZO之间发生了氧化还原反应引发表面活性剂效应,导致界面元素外扩散。本研究将为HZO基FERAM的应用奠定基础。

Conventional chalcogenide materials are hard to remain ferroelectricity when miniatured and poorly compatible with CMOS,hafnium zirconium oxide(HZO)ferroelectric devices compensate the intrinsic defects of conventional chalcogenide with their ability to be miniaturized to within 10 nm with good ferroelectric capacity and still have good compatibility with CMOS.That is why HZO materials have attracted much attention from academia and industry,this material is a promising alternative to dynamic random memories for non-volatile ferroelectric memories(FERAM)and ferroelectric transistor-based integrated circuits.Based on the most widely used TiN/HZO/TiN stack,the in-situ ALD technique with highend application prospects was used to grow TiN electrodes,and the growth rate of the electrode layers and their nanometerscale film thickness were well controlled.The diffusion of elements at the stack interface was investigated,and the phenomenon of external diffusion of interfacial elements was found by time-of-flight secondary ion mass spectrometry.The mechanism of the external diffusion behaviour was investigated by angle-resolved X-ray photoelectron spectroscopy,and a possible theoretical explanation was proposed,i.e.,the external diffusion of interfacial elements due to the surfactant effect triggered by the redox reaction between TiN and HZO.This work shed light to the application of HZO-based FERAM.