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随着特征尺寸不断缩小,CMOS器件已步入纳米尺度范围,因此纳米尺度器件的结构表征变得尤为关键。完备的半导体器件结构分析,要求确定原子位置、局部化学元素组成及局域电子结构。高分辨(分析型)透射电镜及其显微分析技术,能够提供衍衬像(振幅衬度像)、高分辨像(相位衬度像)、选区电子衍射和会聚束电子衍射、X射线能谱(EDS)及电子能量损失谱(EELS)等分析手段,已作为半导体器件结构表征的基本工具。配有高角度环形暗场探测器的扫描透射电镜(STEM),因其像的强度近似正比于原子序数(Z)的平方,它可在原子尺度直接确定材料的结构和化学组成。利用Z-衬度像配合高分辨电子能量损失谱技术,可确定新型CMOS堆垛层中的界面结构、界面及界面附近的元素分布及化学环境。近年来新开发的球差校正器使得HRTEM/STEM的分辨率得到革命性提高(空间分辨率优于0.08 nm,能量分辨率优于0.2 eV),在亚埃尺度上实现单个纳米器件的结构表征。装备球差校正器的新一代HRTEM和STEM,使得高k栅介质材料的研究进入一个新时代。本文首先介绍了原子分辨率电镜(HRTEM和STEM)的基本原理和关键特征,对相关高分辨谱分析技术(如EDS和EELS)加以比较;然后综述了HRTEM/STEM在高k栅介质材料(如铪基氧化物、稀土氧化物和外延钙钛矿结构氧化物)结构表征方面的最新进展;最后对亚埃分辨率高k栅介质材料的结构表征进行了展望。
As feature sizes continue to shrink, CMOS devices have entered the nano-scale range and structural characterization of nano-scale devices has become especially critical. Complete semiconductor device structure analysis, requires the determination of atomic position, local chemical element composition and local electronic structure. High Resolution (Analytical) TEM and its microanalysis technology provide diffraction image (amplitude contrast image), high resolution image (phase contrast image), selected area electron diffraction and convergent beam electron diffraction, X-ray energy spectrum (EDS) and electronic energy loss spectroscopy (EELS) analysis tools have been used as the basic tools for characterization of semiconductor devices. Scanning Transmission Electron Microscopes (STEMs) with high-angle circular dark-field detectors, whose intensity is approximately proportional to the square of the atomic number (Z), directly determine the structure and chemical composition of the material at the atomic scale. Using Z-contrast as well as high-resolution electron energy loss spectroscopy techniques, the interfacial structure, interface and elemental distribution and chemistry of the new CMOS stack can be determined. In recent years, the newly developed spherical aberration corrector has revolutionized the resolution of HRTEM / STEM (better than 0.08 nm in spatial resolution and better than 0.2 eV in energy resolution), enabling structural characterization of individual nanodevices on the Eurasian scale . A new generation of HRTEM and STEM equipped with spherical aberration correctors has led to a new era in the research of high-k gate dielectric materials. In this paper, the basic principles and key features of HRTEM and STEM are introduced firstly, and the related high-resolution spectral analysis techniques (such as EDS and EELS) are compared. Then the HRTEM / STEM is reviewed in high-k gate dielectric materials Hafnium-based oxides, rare earth oxides and epitaxial perovskite structure oxides). Finally, the structural characterization of high-k dielectric materials with high resolution and high resolution is discussed.