Masakatsu Hasuda

A nanofactory by focused ion beam

A focused ion beam (FIB) system is process equipment used to make a wide variety of small structures of various materials by irradiating a focused gallium ion beam of nanometer-order diameter to a surface of specimens and by utilizing spattering etching and ion beam induced deposition. In order to realize greater diversity of structures with use of the FIB system, we developed a technology of making three-dimensional structures by using gas assist etching, and a precision wheel stage to be used in the focused ion beam (FIB) system. Using these technologies with the FIB system, we achieved a nano processing machine which can be called a nano milling machine or a nano lathe.

FIB mask repair technology for electron projection lithography

We have studied stencil mask repair technology with focused ion beam and developed an advanced mask repair tool for electron projection lithography. There were some challenges in the stencil mask repair, which were mainly due to its 3-dimensional structure with aspect ratio more than 10. In order to solve them, we developed some key technologies with focused ion beam (FIB). The transmitted FIB detection technique is a reliable imaging method for a 3-dimensional stencil mask. This technique makes it easy to observe deep patterns of the stencil mask and to detect the process endpoint. High-aspect processing can be achieved using gas-assisted etching (GAE) for a stencil mask. GAE enables us to repair mask patterns with aspect ratio more than 50 and very steep sidewall angle within 90±1°precisely. Edge placement accuracy of the developed tool is about 14nm by manual operation. This tool is capable to achieve less than 10nm by advanced software. It was found that FIB technology had capability to satisfy required specifications for EPL mask repair.

3D Atom Probe Microscopy Sample Preparation by Using L-Shape FIB-SEM-Ar Triple Beam

3D atom probe microscopy (3DAPM) is used as the technique of analyzing the three-dimensional information including chemical composition and atomic structure with near atomic-scale resolution [1]. The near atomic-scale resolution is realized by extracting atoms on a sample surface one by one with electric field evaporation. The needle-like sample with a tip diameter of about 50 nm is required in order to apply the local high electric field to the sample surface.

Transition Edge Sensor (TES) X-ray detecting system with sensitivity correction to stabilize the spectrum peak center

Transition Edge Sensor (TES) is an energy dispersive X-ray detecting system with high energy resolution. The energy resolution of this system depends on the steepness of superconducting transition curve from normal to superconducting state, heat capacitance and the operating temperature. The TES is based on the dilution refrigerator cooled by about 100 mK. The energy resolution is calculated about 1-2 eV for the detector with maximum detecting energy as 10 eV. The energy resolution also depends on the superconducting current flowing through the TES device because the superconducting current is affected by the temperature stability of the refrigerator. The fluctuation of the superconducting current means the fluctuation of the X-ray spectrum peak center. We have developed the sensitivity correction system to stabilize the peak center of the X-ray spectrum. The peak center of X-ray spectrum correlates with heater power to keep the base temperature of TES device at a constant temperature. The peak center of X-ray spectrum is calibrated by monitoring the heater power at constant time interval using the correlation curve between the peak center of X-ray spectrum and heater power.

SEM-TES application to chemical state analysis on cation of electrode materials for electrochemical capacitors based on the sensitivity correction of X-ray intensity data

The microcalorimeter detects the energy of incidentX-ray photon by the slight temperature rise of a device at a very low temperature, and the detector of a superconducting transition-edge sensor (TES) microcalorimeter has been developed for the measurement of energy dispersive X-ray photons of the energy of 10 to 20 keV with the energy resolution better than 100 eV of FWHM value by having the counting rate over 100 counts per second. A FE-SEM with a detector of TES microcalorimeter (SEM-TES) has already been developed for the extra-high resolution energy-dispersive X-ray spectrometry system to apply in electron-microprobe chemical analyses. Recently, we developed the sensitive correct function on the observed X-ray intensity data measured in the system. Then, the high energy resolution of revised SEM-TES system is precisely able to determine the element contents on the sample. In addition, the chemical bonding states can be clarified by the fluorescent X-ray intensities in the lower energy region derived with a low accelerating voltage of SEM-TES system. We applied the revised SEM-TES system to analyze chemical state on the electrode of nanosheets-derived Hx(Ni1/3Co1/3Mn1/3)O2 for newly developing electrochemical capacitors. We investigated the chemicalstate of cations by not the M-lines but the L-beta and L-alpha lines as the lower energy lines having relative large contribution on chemical bonding. As a result, we revealed a specific chemical state of the Mn different from that of Li(Ni1/3Co1/3Mn1/3)O2 electrode in LiB, that was supported by the result of TEM-EELS analysis. These results show that the SEM-TES system can be a useful analytical tool for the chemical bonding state and electronic structure determinations in a wide range of materials.

3D Structure Fabrication by FIB Milling and Deposition

Focused Ion Beam (FIB) system is equipment used to make a wide variety of micro and Nano structures. Structures can be created using various materials by irradiating focused gallium ion beam on to the surface of specimens and by sputtering, etching and ion beam induced deposition. In order to realize greater diversity for nano construction by using the FIB system, we have developed technologies incorporating: - Built-in pattern signal generator - Multiple Gas Unit for gas assisted etching and beam induced deposition - A precision wheel for the stage. This latest FIB system has a narrow Ion beam with a diameter of better than 4nm. Beam current is controlled from 0.15pA to 20nA. These performances contribute significantly to the study 3D structures fabrication and modification.