Takeshi Sunaoshi

Hierarchical nanoporous glass with antireflectivity and superhydrophilicity by one-pot etching.

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.

Lattice imaging at an accelerating voltage of 30kV using an in-lens type cold field-emission scanning electron microscope.

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.

STEM/SEM, Chemical Analysis, Atomic Resolution and Surface Imaging At ≤ 30 kV with No Aberration Correction for Nanomaterials on Graphene Support

Full analytical capabilities considered standard for high-voltage STEM/TEMs at 30kV are expensive and typically require monochromators especially for Schottky emitter based instrumentation [1-3] due to the strangle-hold of the chromatic aberrations. In addition, the power supplies for lenses designed for 200/300kV contribute increasingly to the energy width of the electron beam at the low level currents needed for ≤ 30kV instrumentation. Therefore, enhancing an atomic resolution SEM with a cold field emission gun (cFEG) with STEM, EELS and diffraction capabilities provides an excellent platform for combining surface investigations typically for SEMs with high resolution and analysis capabilities of a typical STEM at comparatively low cost.

A study of electrical characteristic changes in MOSFET by electron beam irradiation

Abstract 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.

Study on short failure localization approach by newly developed EBAC technique

Demand of short failure analysis has been increasing in semiconductor failure analysis. It is known from the previous studies that many short failure analysis methods are suggested. However, it is extremely difficult to identify the short failure location in recent advanced devices due to the fact of optical resolution limit. On the other hand EBAC has been noted as the high resolution method to identify an open or a high resistance failure while it is rather difficult for EBAC to identify a short failure. In this study we have developed a new EBAC amplifier and evaluated a short failure case for identifying the location clearer enough than conventional analysis methods. This paper describes successful use of the new EBAC amplifier which has sufficient enough resolution of EBAC signal to identify the failure locations for next step physical analyses of FIB, STEM or so on.

High Contrast SEM Observation of Semiconductor Dopant Profile using TripleBeam® System

Low-energy Focused Ion Beam (FIB) processing is a key technique to acquire high quality images. The TripleBeam® system to reduce Ga ion milling related damage has been developed [1]. This system has been applied to lamella preparation for several types of materials such as silicon semiconductor integrated circuits and ceramics. This application includes cross sectional high contrast Scanning Electron Microscope (SEM) observation. Experiments conducted by our group have shown that cross sectional observation of high contrast dopant profiling on a SiC semiconductor specimen using Ar ion milling is possible [2]. Despite our success, multiple complex steps with several systems were used for the study such as the use of a FIB, Ion Milling system and a SEM, therefore the throughput was degraded. This paper discusses the high contrast observation of dopant profiling in semiconductor using a triplebeam® system.

Energy Filtered STEM Imaging at 30kV and Below - A New Window into the Nano-World?

Energy filtered imaging has been available for many years for TEMs. Both, the in-column filter by Carl Zeiss [1] and the Gatan Imaging Filter [2] have proven useful and are well documented. Compared to TEM, energy filtering combined with BF-STEM has seen less publicity. This is surprising because BFSTEM by itself has an advantage over TEM: inelastically scattered electrons have less of an effect on the final image quality when compared to TEM. Furthermore, EF (energy-filtered) BF-STEM imaging has been reported as a promising approach [3]. However, EF BF-STEM imaging is handicapped by the requirement of a fast EELS detector: for acquiring a 512 × 512 pixel image in under 1s, an EELS detector capable of 512 × 512 = 262,144 EELS spectra /s is required.

Expanding the Depth of Field for Imaging with Low keV Electrons: High Resolution Surface Observations of Nanostructured LaB6 Using Low keV Secondary and Backscattered Electrons

1. Hitachi High-Technologies Corp., Application Development Department, Ibaraki, Japan. 2. Hitachi High-Technologies Corp., Electron Microscope Systems Design 1st Dept., Ibaraki, Japan. 3. Hitachi High Technologies America, NSD, Clarksburg, Maryland, USA. 4. University of Georgia, Department of Chemistry, Athens, Georgia, USA. 5. University of Georgia, Georgia Electron Microscopy, Athens, Georgia, USA.

Sample preparation technique for the revelation of a semiconductor dopant using an FE-SEM

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.