CAJ | 학술논문

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HRTEMISTEM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.
수착특정척촌불단축소,CMOS기건이보입납미척도범위,인차납미척도기건적결구표정변득우위관건.완비적반도체기건결구분석,요구학정원자위치、국부화학원소조성급국역전자결구.고분변(분석형)투사전경급기현미분석기술,능구제공연츤상(진폭츤도상)、고분변상(상위츤도상)、선구전자연사화회취속전자연사、X사선능보(EDS)급전자능량손실보(EELS)등분석수단,이작위반도체기건결구표정적기본공구.배유고각도배형암장탐측기적소묘투사전경(STEM),인기상적강도근사정비우원자서수(Z)적평방,타가재원자척도직접학정재료적결구화화학조성.이용Z-츤도상배합고분변전자능량손실보기술,가학정신형CMOS퇴타층중적계면결구、계면급계면부근적원소분포급화학배경.근년래신개발적구차교정기사득HRTEM/STEM적분변솔득도혁명성제고(공간분변솔우우0.08 nm,능량분변솔우우0.2 ev),재아애척도상실현단개납미기건적결구표정.장비구차교정기적신일대HRTEM화STEM,사득고k책개질재료적연구진입일개신시대.본문수선개소료-원자분변솔전경(HRTEM화STEM)적기본원리화관건특정,대상관고분변보분석기술(여EDS화EELS)가이비교;연후종술료HRTEMISTEM재고k책개질재료(여협기양화물、희토양화물화외연개태광결구양화물)결구표정방면적최신진전;최후대아애분변솔고k책개질재료적결구표정진행료전망.
As the downscaling of the feature sizes of complementary metal oxide semiconductor (CMOS) devices enters into the "nuno" era, nanoscale structural characterization at device dimensions becomes critical. A full structural analysis of processed semiconductor devices reqnires an ability to determine atomic positions and local chemical elements and electronic structure. Highresolution (analytical) transmission electron microscopes (HR (A)TEM ), which provide the microscopy techniques such as diffraction contrast imaging (smplimde contrast imaging), high-resolution TEM imaging (phase contrast imaging), selected area electron diffraction and convergent beam electron diffraction, and X-ray energy-dispersive spectroscopy (EDS) and electron energy loss spectroscopy (EELS), have become essential metrology tools in the semiconductor industry. Scanning transmission electron microscope (STEM) with high-angle annular dark field (HAADF) imaging (or Z-contrast incoherent imaging) can directly reveal the structure and chemistry of materials at the atomic scale, due to its imaging intensity being approximately proportional to the square of atomic number (Z) of element. By using Z-contrast imaging and high-resolved EELS spectroscopy, it is very powerful to determine the interfacial structures and the elemental/cbemical environment at/around interfaces within advanced CMOS gate stacks. In recent years the new development of aberration corrector (or, Cs-corrector) makes a revolutionizing the performance of HRTEM/STEM instruments, allowing one to achieve a spatial resolution better than 0.08 nm and an energy resolution better than 0.2 eV, thereby making the characterization of individual nanoscale device structure at sub-atomic scale available. The new generation HRTEM/STEM facility equipped with Cs-corrector will benefit high-k gate materials research in the new era. In this review, some basic principles and key features of atomic-resolution electron microscopy, and the associated high-resolution spectroscopy techniques such as EELS and EDS are first introduced. Second, applications of HRTEM/STEM to structural characterizing high-k gate materials, including Hf-bnsed oxides, rare-earth oxides, and epitaxial perovskite oxides, are critically reviewed. Finally, we conclude this review with personal perspectives towards the future prospects of the characterization of highk gate dielectrics at sub-angstrom level.