High-resolution three-dimensional scanning transmission electron microscopy characterization of oxide-nitride-oxide layer interfaces in Si-based semiconductors using computed tomography

Oxide-nitride-oxide (ONO) layer structures are widely used for charge storage in flash memory devices. The ONO layer interfaces should be as flat as possible, so measurement of the nanoscale roughness of those interfaces is needed. In this study, quantification of an ONO film from a commercially available flash memory device was carried out with a pillar-shaped specimen using scanning transmission electron microscopy (STEM) and computed tomography. The ONO area contained only low Z- and low STEM-contrast materials, which makes high-quality reconstruction difficult. The optimum three-dimensional reconstruction was achieved with an STEM annular dark-field detector inner collection angle of 32?mrad, a sample tilt range from -78° to +78° and 25 iterations for the simultaneous iterative reconstruction technique.     

Progress in aberration-corrected scanning transmission electron microscopy

A new corrector of spherical aberration (C(S)) for a dedicated scanning transmission electron microscope (STEM) is described and its results are presented. The corrector uses strong octupoles and increases C(C) by only 0.2 mm relative to the uncorrected microscope. Its overall stability is greatly improved compared to our previous design. It has achieved a point-to-point resolution of 1.23 A in high-angle annular dark field images at 100 kV. It has also increased the current available in a 1.3 A-sized probe by about a factor of ten compared to existing STEMs. Its operation is greatly assisted by newly developed autotuning software which measures all the aberration coefficients up to fifth order in less than one minute. We conclude by discussing the present limits of aberration-corrected STEM, and likely future developments.     

透射电镜电子染色方法的改良

为提高透射电镜生物样品超薄切片的染色效率,在传统染色方法基础上进行改良,使用自制染色装置,在较短时间内完成大批生物样品超薄切片的电子染色。与传统方法相比较省时省药,减少污染机率,电镜观察的超微结构清晰,反差较好。     

Correlative light microscopy, scanning electron microscopy, and transmission electron microscopy of osmium-macerated biological tissues

A method facilitating correlation of light microscopic (LM), scanning electron microscopic (SEM) and transmission electron microscopic (TEM) images was developed. Rat kidney and heart were initially subjected to the osmium maceration procedure and then embedded in acrylic resin. Semithin sections of the tissue blocks were first provided for LM and then examined by SEM after resin removal. Furthermore, the ultrathin sections adjacent to the semithin sections were observed by TEM. The three-dimensional images of intracellular organelles provided an informative adjunct to LM and TEM.     

Optimizing the environment for sub-0.2 nm scanning transmission electron microscopy

Sub-0.2 nm probes can now be readily obtained on Schottky field-emission microscopes. However, environmental instabilities are proving to be the limiting factors for atomic resolution spectroscopy and distortion-free annular-dark field imaging. This is a result of the long acquisition times and the serial nature of the scanning system where instabilities result in image distortions rather than reductions in contrast. Troubleshooting the most common environmental problems is discussed here. In addition to the expected sensitivity to mechanical vibration, electromagnetic interference and temperature variations, air-pressure fluctuations are found to have a significant impact on microscopes with side-entry goiniometers.     

家兔骨骼肌样品染色技术的改进

采用常规染色方法所制备的家兔骨骼肌样品,其图像中易出现小黑斑。本文在常规染色方法基础上进行改良,有效减少了黑斑的出现,其超微结构清晰,反差也有所增强。     

Electron-beam-induced-current investigation of GaN/AlGaN/Si heterostructures using scanning transmission electron microscopy

An electron-beam-induced-current technique has been applied to scanning transmission electron microscopy to characterize GaN/AlGaN/n-Si heterostructures. The structure was formed by metalorganic vapor phase epitaxy using AlGaN as an intermediate layer. Two samples with nominal intermediate layer thicknesses of 60 and 120 nm were studied. It was found that there is a junction in the n-type Si region underneath the nitride/Si interface irrespective of the intermediate layer thickness, whereas induced current occurred neither in the nitride region nor at the nitride/Si interface. The junction formed was found to be undulated. The sample with the thin intermediate layer had undulations of a shorter periodicity than that with the thick intermediate layer. The formation of the junction is attributed to the diffusion of Al during the nitride growth.     

放线菌扫描电镜样品制备方法比较研究

目的:比较和筛选放线菌扫描电镜样品制备方法。方法:通过培养获得插片、菌饼和发酵液3种待处理样品,根据单因素试验设计原则采用双固定、单固定、磷酸缓冲液清洗、生理盐水清洗、蒸馏水清洗、丙酮脱水、乙醇脱水和直接表面镀金等8种方法对样品进行处理。结果:取样时间直接影响观察样品形态的丰富度;插片样品扫描获得的结果较为理想;不同的固定、清洗和脱水等处理过程也对样品的细节产生了影响。结论:插片样品直接干燥喷金扫描观察是一种简便、快速的方法,对于常规的放线菌观察与鉴定较为实用,也为其它微生物扫描电镜观察提供了参考。     

New views of materials through aberration-corrected scanning transmission electron microscopy

The successful correction of third-order and, more recently, fifth-order aberrations has enormously enhanced the capabilities of the scanning transmission electron microscope (STEM), by not only achieving record resolution, but also allowing near 100% efficiency for electron energy loss spectroscopy, and higher currents for two-dimensional spectrum imaging. These advances have meant that the intrinsic advantages of the STEM, incoherent imaging and simultaneous collection of multiple complementary images can now give new insights into many areas of materials physics. Here, we review a number of examples, mostly from the field of complex oxides, and look towards new directions for the future.     

Bond integrity evaluation using transmission scanning acoustic microscopy

Low frequency transmission scanning acoustic microscopy is capable of revealing voids and delaminations at substantial depths inside a solid material. The technique is demonstrated with reference to the bond between a carbon diamond compound sintered to a steel base. A resolution comparable to the wavelength inside the solid material is achieved.     

小血管的扫描电镜样品制备法

在小血管的扫描电镜样品制备过程中 ,由于血管干燥之后 ,血管弹力板层像棉花一样极不易切割 ,强行切割时会出现撕裂血管壁的现象。我们试用强力万能胶粘剂对样品进行处理 ,获得了满意的效果 ,此法尚未见文献报道 ,现介绍如下。材料和方法取白鼠做显微手术 ,经腹动脉插管 ,开放下腔静脉 ,行生理压原位固定 ,肝素化的林格氏液(Ｒｉｎｇｌｒｓ)冲洗 ,在吻合口取 4～ 8ｍｍ长的小血管 ,放入 3%戊二醛固定液中固定 2ｈ ,用 0 1ｍｏｌ Ｌ磷酸缓冲液冲洗 3次 ,每次 1 5ｍｉｎ ,用 5 0 %、70 %、80 %、90 %、95 %、1 0 0 %的液体叔丁醇梯度脱水置换…     

游离细胞超快扫描电镜样品制备法

在游离细胞的扫描电镜样品制备方法中 ,需要解决的关键问题是如何使细胞均匀而又不重叠地分布于盖玻片上 ,同时在一系列处理过程中细胞不易脱落。用常规的方法进行处理 ,步骤繁琐 ,所用时间又长且在样品处理过程中细胞有丢失现象。我们用细胞沉淀器加微波辐射技术进行游离细胞快速扫描电镜样品制备 ,获得满意的结果 ,现介绍如下。材料和方法1 .主要仪器 :本实验所用微波炉的型号为ＷＢＬ 5 30 0 1型 (国营陕西商洛通达电器厂生产 ) ,工作频率 2 45 0ＭＨｚ ,最大输出功率为 5 30Ｗ ,微波辐射时在微波炉底盘一边放一个 5 0 0ｍｌ烧杯 ,内盛5…     

A modified back-etch method for preparation of plan-view high-resolution transmission electron microscopy samples

A modified back-etch method is described that has been successfully used to prepare samples of thin films and nanoparticles on Si wafer substrates for examination by high-resolution transmission electron microscopy (HRTEM). This process includes ultrasonic cutting, abrasive pre-thinning and a two-stage etching procedure. Unlike previous reports of back-etching methods, tetramethyl ammonium hydroxide, which has a very high-etching selectivity of Si to SiO(2), is used for the final etching to allow removal of the Si without degradation of the SiO(2) membrane. An innovative wrapping method is also described. This novel approach reduces the preparation time for HRTEM samples to <1 h per sample for groups of 10 or more samples. As an example, the preparation of FePt nanoparticle samples for HRTEM imaging is described.