Focused Ion Beam Microsampling Research Articles

Combined FIB microsampling and X-ray microtomography: a powerful tool for the study of tiny fluid inclusions

Detailed morphological studies including phase-volume estimation were performed on a natural fluid inclusion in an eclogite-facies rock collected from the Sanbagawa metamorphic belt in Japan. The studied fluid inclusion, which is composed of H2O–NaCl liquid and a CH4 bubble, was picked up by using a focused ion beam (FIB) system and investigated by synchrotron-radiation-based X-ray microtomography (XCT), which provides a submicrometer spatial resolution. By using the FIB-XCT technique, we can perform detailed three-dimensional morphological studies on tiny objects (<10 μm) in combination with several other analytical techniques, such as Raman spectroscopy. The XCT image of the fluid inclusion (~7 μm in size) clearly shows a faceted shape, which corresponds fairly well to the interfacial relationship of α -quartz. This euhedral morphology also satisfies the crystal orientation of the host quartz, and hence is considered a negative crystal. The XCT determination of liquid and vapor-phase volumes in the fluid inclusion is in excellent accordance with the value estimated by the combination of microthermometry and the equation of state of the H2O–NaCl–CH4 system. Furthermore, this agreement indicates that XCT observation is applicable for volumetric analysis of more complex multi-phase systems, regardless of their compositions and phase numbers. Combining the volume fraction of the fluids with the characterization and densimetry of each liquid/gas phase, we can accurately estimate the bulk composition and molar volume of the fluid inclusion. The isochore calculation of the estimated bulk properties shows lower- P conditions than the peak P-T conditions of the rock, although the inclusion was trapped during the pressure-increasing stage. This is possibly caused by density reequilibration during decompression and cooling of the host metamorphic rock. The estimated isochore and the decompression P-T path from literature intersect at 0.2–0.3 GPa and 300°C, which is consistent with the fluid density closure temperature proposed in the literature for quartz-hosted fluid inclusions. The present study demonstrates powerful potential of the FIB-XCT technique for performing morphological observations on tiny fluid inclusions a few micrometers across. With increasing availability of high-resolution XCT systems, the FIB-XCT technique combined with existing fundamental methods provides a new investigative tool for fluid inclusion studies, and may be especially valuable for complex inclusions that are difficult to analyze by other methods.

Shave-off depth profiling: Depth profiling with an absolute depth scale

Shave-off depth profiling provides profiling with an absolute depth scale. This method uses a focused ion beam (FIB) micro-machining process to provide the depth profile. We show that the shave-off depth profile of a particle reflected the spherical shape of the sample and signal intensities had no relationship to the depth. Through the introduction of FIB micro-sampling, the shave-off depth profiling of a dynamic random access memory (DRAM) tip was carried out. The shave-off profile agreed with a blue print from the manufacturing process. Finally, shave-off depth profiling is discussed with respect to resolutions and future directions.

A FIB Micro-Sampling Technique for Three-Dimensional Characterization of a Site-Specific Defect

Abstract In characterization or failure analysis of new materials and semiconductor devices, the requirements for three dimensional observation and analysis are rapidly increasing. We discuss techniques for specimen preparation, three-dimensional observation, and elemental analysis of semiconductor devices that we developed using a system consisting of a dedicated focused ion beam (FIB) instrument and a scanning transmission electron microscope (STEM). The system utilizes a FIB-STEM compatible specimen holder with a specially designed rotation mechanism, which allows 360° rotation of a specimen on a conical stage (needle stub) around the ion beam axis of the FIB system and 360° rotation perpendicular to the electron beam in the STEM. A piece of sample (micro sample) is extracted from a specific-site by the micro-sampling technique and mounted on the needle stub. Instruments used in the study are the Hitachi FB-2100 FIB system with a micro-sampling attachment and the HD-2300 field emission 200kV STEM.

Specimen preparation for high-resolution transmission electron microscopy using focused ion beam and Ar ion milling

We have developed a focused ion beam (FIB)-Ar ion-milling technique for high-resolution transmission electron microscopy. A micrometresized specimen was mounted on a cross section of metal foil of a few micrometres thick, using FIB microsampling. Following this, a 2 degrees wedgeshaped part was made in the specimen using FIB. Finally, the specimen was milled using an Ar ion beam to remove the FIB-damaged layers. We applied the FIB-Ar ion milling technique to a CeO(2)/Gd(2)Zr(2)O(7) multilayer specimen, resulting in the crystal lattice fringes of both layers being clearly observable in comparison to a specimen finished using a Ga ion beam at an accelerating voltage of 10 kV.

Application of FIB microsampling technique to long-period ordered TiAl single crystal with composition gradient

Metastable long-period superstructures in an L10-TiAl single crystal with a composition gradient were observed successfully by transmission electron microscopy with a focused ion beam (FIB) microsampling technique. The composition gradient from 54.7 to 75 at.% Al with approximately 6 microm width was detected by electron probe microanalysis and foil specimens containing the composition-gradient area were fabricated by the FIB microsampling method. The foil specimens clearly exhibit sequential changes in long-period superstructure depending on the Al concentration.

Application of a FIB-STEM system for 3D observation of a resin-embedded yeast cell

The combination of a focused ion beam (FIB) system and a scanning transmission electron microscope (STEM) has been applied to the three-dimensional (3D) observation of a resin-embedded yeast cell. Using a FIB microsampling technique, a sample with a thickness of tens of micrometres was extracted from a resin-embedded block sample. The extracted sample was transferred to a FIB-STEM-compatible specimen rotation holder and trimmed by FIB milling for 3D STEM observation. Although the FIB milling was carried out at an operating voltage of 40 KV, the sample was cross sectioned without forming a harmful damage layer on its surface. Cell structures, such as cell wall, cell membrane, mitochondria, peroxisomes, endoplasmic reticulum and vacuoles, were observed clearly in a pillar-shaped sample of 20 microm long, 4 microm wide and 3 microm deep.

A FIB Micro-Sampling Technique and a Site-Specific TEM Specimen Preparation Method for Precision Materials Characterization

AbstractA technique to cut out small pieces of samples directly from chips or wafer samples in a focused ion beam (FIB) system has been developed. A deep trench is FIB milled to cut out a small, wedge-shaped portion of the sample from the area of interest A micromanipulator with tungsten (W) probe is employed for lifting the micro-sample. The lifted micro-sample is then mounted on a carrier to prepare electron transparent thin foil specimens for transmission electron microscope (TEM) observation. We have also developed a method for site-specific TEM specimen preparation. In this method, FIB system and TEM/scanning transmission electron microscope (STEM) equipped with secondary electron (SE) detector are employed. An FIB–TEM/STEM compatible specimen holder has also been developed so that a specimen can be milled in the FIB system and observed in a TEM/STEM without remounting the specimen. STEM and scanning electron microscopy (SEM) images are used for locating a specific site on a specimen. SEM image observation at an accelerating voltage of 200kV enabled us to observe not only surface structures but also inner structures near the surface of a cross section with depth of field of around 1 micrometer. The STEM image allows the observation of inner structures of 3-5 micrometer thick specimens. Milling of a specimen by FIB and observation of the milled sample by SEM and STEM are alternately carried out until an electron transparent thin foil specimen is obtained. The position accuracy of the method in TEM specimen preparation is approximately 100nm.