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To realize high specific capacity Li-metal batteries, a protection layer for the Li-metal anode is needed. We are carrying out combinatorial screening of Li-alloy thin films as the protection layer...

The scanning electron microscope (SEM) has been reassembled into a new type of cryo-electron microscope (cryo-TSEM) by installing a new cryo-transfer holder and anti-contamination trap, which allowed simultaneous acquisition of both transmission images (STEM images) and surface images (SEM images) in the frozen state. The ultimate temperatures of the holder and the trap reached − 190 °C and − 210 °C, respectively, by applying a liquid nitrogen slush. The STEM images at 30 kV were comparable to, or superior to, the images acquired with conventional transmission electron microscope (100 kV TEM) in contrast and sharpness. The unroofing method was used to observe membrane cytoskeletons instead of the frozen section and the FIB methods. Deep sublimation of ice surrounding unroofed cells by regulating temperature enabled to emerge intracellular fine structures in thick frozen cells. Hence, fine structures in the vicinity of the cell membrane such as the cytoskeleton, polyribosome chains and endoplasmic reticulum (ER) became visible. The ER was distributed as a wide, flat structure beneath the cell membrane, forming a large spatial network with tubular ER.

A new type of cryo-electron microscopy (cryo-S(T)EM) technique made possible by installing a new cryo-transfer holder and an anti-contamination trap on a scanning electron microscope (Hitachi SU9000) allowed simultaneous collection of both transmission (transmission electron microscopy, TEM) images and surface (scanning electron microscopy, SEM) images at -180°C. The ultimate temperatures of the cryo-transfer holder and the anti-contamination trap reached − 190°C and − 210°C, respectively, by applying a liquid nitrogen slush. The TEM images obtained by the new cryo-S(T)EM method showed quality equal or superior to that of images obtained by conventional 100 kV TEM, although the resolution did not improve at -180°C due to slight drifting of the sample stage. Cryo-S(T)EM also had the unexpected advantage of enabling observations of intracellular structures in thick frozen cells by accelerating the sublimation of ice surrounding the specimens. The spatial architecture of the cytoskeleton, poly-ribosome-chains, endoplasmic reticulum (ER), mitochondria, etc., became visible in thick frozen cells via sufficient (deep) sublimation of ice in combination with the unroofing method. In particular, it should be noted that the ER appeared as a wide and flat structure beneath the cell membrane while forming a large spatial network together with tubular ER.

A new and exciting imaging technique being applied to thin films, nanocoatings, nanogels, and nanoparticle analysis is ultra-low accelerating voltage or ultra-low-landing-energy scanning electron microscopy (ULVSEM). Instrument conditions in this mode are different than with typical SEM observation or contemporary low accelerating voltage (LVSEM) imaging. Hence, the images appear far different due to reduced beam penetration. The landing energy of the primary electron beam can be much lower than LVSEM, it can be reduced to far below 500 electron volts (eV), even as low as 10 eV. Thus, the electron beam range and penetration are reduced tremendously with some unavoidable loss of spatial resolution. Surface details are enhanced, contrast might favorably change, and secondary electron (SE) edge enhancement or “blooming” contributing to measurement uncertainty is greatly reduced, potentially allowing for more precise and new measurements once this imaging mode is fully characterized and accurately modeled. High-resolution field-emission electron sources, improved lens, detector designs, and sample biasing all contribute to the ability to image at such low electron landing energies. The techniques of ULVSEM are discussed, and an application example is presented.

Carbon-black-supported nanoparticles (CNPs) have attracted considerable attention for their intriguing catalytic properties and promising applications. The traditional liquid synthesis of CNPs commonly involves demanding operation conditions and complex pre- or post-treatments, which are time consuming and energy inefficient. Herein, a rapid, scalable, and universal strategy is reported to synthesize highly dispersed metal nanoparticles embedded in a carbon matrix via microwave irradiation of carbon black with preloaded precursors. By optimizing the amount of carbon black, the microwave absorption is dramatically improved while the thermal dissipation is effectively controlled, leading to a rapid temperature increase in carbon black, ramping to 1270 K in just 6 s. The whole synthesis process requires no capping agents or surfactants, nor tedious pre- or post-treatments of carbon black, showing tremendous potential for mass production. As a proof of concept, the synthesis of ultrafine Ru nanoparticles (≈2.57 nm) uniformly embedded in carbon black using this microwave heating technique is demonstrated, which displays remarkable electrocatalytic performance when used as the cathode in a Li-O2 battery. This microwave heating method can be extended to the synthesis of other nanoparticles, thereby providing a general methodology for the mass production of carbon-supported catalytic nanoparticles.

A new band-pass energy filter (BPF) technique of secondary electron (SE) detection using scanning electron microscope (SEM) was developed to enhance voltage contrast (VC) in SEM images. The energy filtering condition was optimized to enhance VC of dopant distribution using Si p-n structure. The relation between VC and SE energy was investigated by BPF as well as a conventional high-pass filter (HPF). Whereas the p-type regions were always brighter than the n-type region in the case of HPF, the contrast reversal between p region and n region occurred at the low SE energy range in the case of BPF. The variation of signal intensity of BPF against specimen bias voltage can be considered as SE spectrum analysis, and the peak split of the spectra between n-type and p-type regions was obtained. The peak split can be explained with a model with metal-semiconductor contact. This peak split causes the contrast reversal.

Miniaturization scaling of technology node is advancing in recent years, we are almost facing to the age of mass production for ultra-fine devices with the design rule of one-digit nanometers. Along with the scaling of technology node, distance of neighboring wires or contact plugs is inevitably reduced, and so, occurrences of short circuit defect are increasing. So far, various methods had been applied for investigating short-circuit failures. The failure analysis by SEM based electron beam absorbed current (EBAC) technique recently becomes main-stream technique among them because of its spatial resolution to determine the failure position. The DI EBAC that is the EBAC observation acquired by applying some voltage to the failure short circuit and forcing to run bias current through it was known to be effective to fix the malfunction position of failure short circuit. However, it is necessary for making the evaluation condition of the DI EBAC to have the best results. Especially, malfunction area localization for low resistive short failure is difficult by conventional technique, thus, the focus point of measurement condition is to find out DI EBAC short failure localization ability for low resistive short failure mode. In this study, several samples and measuring parameters were evaluated to find the most effective conditions in the DI EBAC. We confirmed that suitable measurement condition was possible to obtain hotspot signals in actual short failure analyses as low resistive shorted failure sample.

It is challenging to obtain the dopant profile within semiconductor devices with sufficient contrast from FIB milled cross sections due to a damage layer being formed during the milling process. In order to obtain accurate and sufficient dopant profile information, we examined FIB processing conditions and Ar ion milling conditions using a standard sample. As a result, an accelerating voltage of 40 kV for FIB processing and an accelerating voltage of 0.5 kV in Ar ion milling is the most suitable combination for observing a dopant profile clearly. We also applied an optimized preparation protocol to a commercial NMOS sample to demonstrate dopant profile visualization.

Mechanisms for electrical characteristic changes in MOSFET caused by electron beam irradiation were studied using a SEM-based nano-probing system. A shift in V th occurs when a hole is trapped in a defect (oxygen vacancy) in the gate dielectric layer. Holes are generated when the plasmon is excited by electron beam irradiation. Further, an electric field is created by the positive charge-up resulting from electron beam irradiation of the ILD, causing an increase in leakage between gate and drain leading to an increase in I off . This study shows that advanced devices can be measured using a SEM-based nano-probing system without inducing electrical characteristic changes by optimizing the measurement conditions such as acceleration voltage, electron beam current, image magnification, ILD thickness, and electron beam irradiation time.

We have developed a hierarchical nanoporous layer (HNL) on silicate glass by a simple one-pot etching method. The HNL has a three-dimensionally continuous spongelike structure with a pore size of a few tens of nanometers on its apparent surface. The pore size gradually decreases from the apparent surface to the HNL–bulk interface. This HNL bestows significant properties to glass: low optical reflectivity that reflects 7% less visible light than nontreated glass and long-persistence superhydrophilicity that keeps its water contact angle at about 5° for more than 1 year. The superhydrophilicity also realizes antifogging and antifouling functionalities.

We reported investigation of lattice resolution imaging using a Hitachi SU9000 conventional in-lens type cold field emission scanning electron microscope without an aberration corrector at an accelerating voltage of 30kV and discuss the electron optics and optimization of observation conditions for obtaining lattice resolution. It is possible to visualize lattice spacings that are much smaller than the diameter of the incident electron beam through the influence of the superior coherent performance of the cold field emission electron source. The defocus difference between STEM imaging and lattice imaging is found to increase with spherical aberration but it is possible to reduce the spherical aberration by reducing the focal length (f) of the objective lens combined with an experimental sample stage enabling a shorter distance between the objective lens pre-field and the sample. We demonstrate that it is possible to observe the STEM image and crystalline lattice simultaneously. STEM and Fourier transform images are detected for Si{222} lattice fringes and reflection spots, corresponding to 0.157nm. These results reveal the potential and possibility for a measuring technique with excellent precision as a theoretically exact dimension and established the ability to perform high precision measurements of crystal lattices for the structural characterization of semiconductor materials with minimal radiation beam damage.

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.