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The present reconstruction method of Atom Probe Tomography (APT) has the problem that the parameter, in particular the shank angle which represents the region the signal of APT is detectable, is adjusted according to the internal length reference of the sample. The reliable APT reconstruction image could not be obtained in the sample without the reference. We propose the method to calculate the value of the shank angle from the shape of sample and the geometric position relationship between the sample and the detector. We compared the APT reconstruction image in this method to the image in the conventional method with the sample of Si isotope superlattice. The result is that APT 3D image by the new method was reconstructed equivalently to the image by the conventional method. [DOI: 10.1380/ejssnt.2015.235]

Shave-off depth profiling uses a Ga focused ion beam micro-machining process to provide highly precise depth profiles with nanometer-scale resolution. This method is a very unique process for acquiring a depth profile using the shave-off scan mode, in which the primary ion beam perpendicular to the direction of depth irradiates the sample. In our previous study, we confirmed by molecular dynamics simulation that the shave-off scan mode has a low mixing effect compared with the conventional scan mode, which uses the normal incident angle. However, the current understanding of measurement using the shave-off scan mode is insufficient. In this study, in order to estimate the sample damage in the shave-off scan mode, we investigated the degree of mixing effects after the primary ion bombardment under shave-off conditions using atom probe tomography. To evaluate the mixing effects, the intermixing of silicon isotope multilayers induced by ion beam irradiation was investigated. The depth of the damage from the sample surface caused by Ga focused ion beams was analyzed for both the shave-off scan mode and the conventional scan mode using the normal incident angle. Results showed that the shave-off scan mode has a significantly smaller mixing effect thanthe conventionalscanmode. Inaddition, results showed that the attenuations of the damage and the Ga concentration exhibited almost the same tendency. Copyright © 2014 John Wiley & Sons, Ltd.

Three-dimensional microanalysis of the microstructure of organic materials is important in the development and progress of analytical methods on the micro-to-nanometer scales. We have developed a novel three-dimensional microanalysis method using focused ion beams for section processing (shave-off scanning) and time-of-flight secondary ion mass spectrometry for mapping. Shave-off scanning can effectively create an arbitrary section on a sample set against composites materials with a wide variety of shapes; three-dimensional sample images are then obtained by alternately operating two focused ion beams. In this study, we adapted metal-assisted secondary ion mass spectrometry for three-dimensional microanalysis. We have devised a unique method whereby gold is deposited on a section to be analyzed after every shave-off sectioning by setting a gold plate at the back of the sample. Consequently, gold was observed to be deposited on the created cross-section concurrently with shave-off sectioning, resulting in a substantially enhanced secondary ion intensity. Copyright © 2014 John Wiley & Sons, Ltd.

Shave-off depth profiling achieves the highly precise depth profiling with nanometre-scaled depth resolution by using a focused ion beam micro-machining process to provide depth profile. This method has its own features: absolute depth scale, pinpoint depth profiling and application for rough surface and/or hetero interface. Although this method has significant features, the quantitative evaluation of the fundamental predominance in shave-off depth profiling is still insufficient because the shave-off scanning mode has a distinctive position of the primary ion beam against the sample. In this study, the sputtering yield and the mixing effects under the shave-off scan mode were investigated using molecular dynamics simulation. The obtained sputtering yields under the shave-off and the raster modes accorded well with experimental results. The results of sputtering yields and root mean square displacement suggested that the shave-off scan mode has a high sputtering yield and low mixing effects compared with the raster scan mode. In addition, the distribution of the marker atoms clearly showed the process of mixing. Copyright © 2012 John Wiley & Sons, Ltd.

Recently, laser pulses on a three-dimensional atom probe have been used to trigger the field evaporation. The advantages of laser-pulse atom probes are high mass resolution and application to higher resistivity materials such as semiconductors. Most recent studies using laser pulses have indicated that the field evaporation of atoms occurred by a thermal pulsing mechanism. In this study, we analyzed the metal specimens, tungsten, nickel and aluminum, by using the hand-made 3DAP in our laboratory, and verified the mechanism of field evaporation by laser pulses. From the results, the spatial resolution might be extremely better at lower tip temperature. The difference of mass resolution between the laser-irradiated and shadow sides was observed and this might resulted from the difference of cooling duration in both sides. In the reconstruction calculation, the difference of curvature radii in the laser-irradiated and shadow sides was compensated and the spatial resolution was evaluated. [DOI: 10.1380/ejssnt.2011.375]

Secondary Ion Mass Spectrometry (SIMS) has been used as an analysis tool for biological samples using cluster ions of C60, Bin, etc. However, because of bad focusing of cluster ions, accurate three-dimensional analysis is difficult. On the other hand, FIB (Focused Ion Beam) using Ga ions can be focused to about 50 nm, and applied to samples of micro region such as biological samples. However, three-dimensional analysis is difficult because of surface damage by primary ions. Therefore, we have developed Shave-off section processing method. Shave-off scan is extremely unique section processing method. Raster scan of FIB is very slow in vertical direction compared with in horizontal direction. In this study, we evaluated surface damage in section processing and carried out three-dimensional analysis of biological sample using Dual FIB ToF-SIMS with Shave-off scan. We evaluated surface damage by primary ions and actually analyzed biological sample with Shave-off scan. We demonstrated the utility of this instrument by analyzing biological samples.

Shave-off profiling with nano-beam SIMS achieves the highly precise depth profiling with nanometer-scaled depth resolution by utilizing FIB micro-machining process to provide depth profile. This method is very unique depth profiling for acquiring a depth profile by shave-off scanning mode (A fast horizontal sweep of FIB is combined with the very slow vertical sweep). Shave-off profiling has its own features; absolute depth scale, pin point depth profiling and application for rough surface and/or hetero interface. However, the discussion of the sputtering mechanism in shave-off profiling is still insufficient because shave-off scanning mode has distinctive position of the primary ion beam against the sample. In this study, we discussed the difference of sputtering mechanism between shave-off scan and conventional raster scan from the view point of sputtered atom yields of experimental results and calculation results. In addition, the molecular dynamics (MD) simulation under shave-off condition is improved in order to visualize the sputtering mechanism of shave-off profiling. As a result,‘shave-off sputtered atom yield’is rather high compared to conventional sputtered atom yield according to distinctive sputtering mechanism of shave-off scanning mode. [DOI: 10.1380/ejssnt.2011.386]

Three-dimensional microanalysis for a minute structure that consists of organic compounds and polymers is important to make progress and to practically use the method to analyze a micro-nanometer order area. We developed a novel three-dimensional microanalysis method by means of focused ion beams (FIB) for section processing (shave-off scanning) and ToF-SIMS for mapping method. In this study, in order to obtain three-dimensional sample image, we used a laminated film as a sample and examined two-dimensional ToF-SIMS mapping over the cross-section created by shave-off scanning. We could obtain ion map and ToF-Mass spectra of polymer samples. This result suggested that shave-off section processing can suppress the damage by primary ions. [DOI: 10.1380/ejssnt.2011.426]

In our previous study, we proposed the optimum specimen preparation method in atom probe analysis, in which the analytical part was attached to the support needle by the physical strength of carbon deposition in connected hole. The optimum method was concluded from the point of view of the strength at the attachment part under high electric stress and fabrication feasibility. In this study, the rupture frequency of the specimens and the fabrication time were also evaluated, and an optimum method was reexamined. As a result, it was concluded that the optimum methods were the methods in which the analytical part was attached to the support needle by the physical strength of carbon deposition in connected hole and by the physical strength of the hooked joint of analytical part and support needle. [DOI: 10.1380/ejssnt.2011.348]

T.Yamamoto,, Y. Hanaoka, N. Mayama, T. Kaito, T. Adachi, M. Nojima 3 and M. Owari 1,4 1 Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan 2 SII Nanotechnology Inc., 36-1 Takenoshita, Oyama-cho, Sunto-gun, Shizuoka 410-1393, Japan 3 Research Institute of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan 4 Environmental Science Center, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan y1ndggi7@iis.u-tokyo.ac.jp

Yuya Hanaoka,* Norihito Mayama, Tetsuo Terakawa, Takuya Yamamoto, Yasuko Kajiwara, Tatsuo Iwata, Masahiro Taniguchi and Masanori Owari Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan Department of Electrical and Electronic Engineering, Mie University, 1577 Kurimamachiya, Tsu, Mie, 514-8507, Japan Division of Applied Chemistry, Department of Bioengineering and Chemistry, Kanazawa Institute of Technology, 7-1 Ohgigaoka, Nonoichi, Ishikawa 921-8501, Japan Environmental Science Center, The University of Tokyo,7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japam *yhanaoka@iis.u-tokyo.ac.jp

Shave-off depth profiling is one of the powerful methods that can be applied to the analysis of pin point and small region devices. However, acquired shave-off depth profile is affected by a long tail of the FIB because shave-off scanning mode has the distinctive position of the primary ion beam against the sample. In this study, we evaluated the influence of the long tail of the FIB in detail by the simulation method we newly proposed. The evaluation was carried out from the point of view of mainly two factors. One is thickness of the protection film. The other is the scanning speed toward the depth direction. In addition, we newly proposed the notion of ‘shave-off sputtered atom yield’, the important factor of shave-off depth profiling. As a result, it became possible that the determination of optimized experimental condition for the achievement of the ultimate depth resolution.

Three-dimensional atom probe (3DAP) has been developed in our laboratory. In our instrument, the position-sensitive detector with a diameter of 120 mm following a pair of microchannel plates (MCP) was set up at a distance of 110 mm in front of the apex of the sample. Our original preset-type sample stage with a local microelectrode was adopted. The pulse laser, or voltage pulse, was used as a trigger for field evaporation. The pulse width of the laser was 180 fs at a wavelength of 1030 nm. The pulse width of the voltage pulse was less than 10 ns. The performance of our instrument was widely tested with the pure tungsten samples fabricated by the electropolishing and focused ion beam methods. The flight path compensation of detected ions, including the small inclination of MCP assembly, led to the good mass resolution approximately 220 (FWHM). By this compensation, we realized full 0.75 sr acceptable angle 3DAP. The detection efficiency of emitted ions was estimated to be about 50% from the three-dimensional reconstruction images of samples.

In this study, we report the characterization of carbonaceous films deposited on metal substrates by liquid-phase electrodeposition in methanol. The characterization of carbonaceous films by electrodeposition was examined by means of Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), electron energy loss spectroscopy (EELS), secondary ion mass spectrometry (SIMS), atom probe (AP) and high resolution-elastic recoil detection analysis (HR-ERDA). From these results, it was found that the films deposited on the metal substrates were composed of the sp2 and sp3 carbon contents, of which the ratio was about 7:3. Furthermore, the films by electrodeposition contained much hydrogen. The hydrogen contents in the surface were about 60 at.% and those in the subsurface were a few 10 at.%.

We focused on failure within fine copper patterning on a semiconductor chip. Three grades of samples were prepared; hard CMP treatment, soft CMP treatment and standard, and compared the differences by shave-off profiling. The shave-off profiles of CMP treatment revealed a saw-toothed structure, and the shave-off profile of a standard chip was revealed as a periodic triangular wave. The difference can be explained by the existence of residue on the CMP process. Copyright © 2010 John Wiley & Sons, Ltd.

In our previous study, we introduced a new specimen preparation method for the three-dimensional atom probe in which the materials were pared off from oblique back by Ga-FIB. It was suggested that there was a possibility of reducing the gallium implantation in the analyzable regions by using the method. In this study, the gallium implantation level of the method was evaluated with better statistical accuracy by extending the analyzed volume and improving the mass resolution. The specimens were fabricated by means of the conventional and our new methods, and analyzed by atom probe with voltage or laser pulses. The mass spectra with the larger analyzed volume or counts of detected ions and the higher mass resolution than those of our previous study were obtained. Then, the ratio of gallium ions to all detected ions was calculated with better statistical accuracy and it was confirmed that the gallium ion concentration at the surface area was reduced close to or less than the detection limits of our instrument by our new method. [DOI: 10.1380/ejssnt.2010.141]

Shave-off depth profiling utilizes a focused ion beam (FIB) micro-machining process to provide the depth profile. This method is a very unique depth profiling for acquiring a depth profile by the shave-off scanning mode (The fast horizontal sweep of FIB is combined with the very slow vertical sweep). Shave-off depth profiling has its own features, absolute depth scale, pin point depth profiling and application for rough surface and hetero interface. However, the shave-off depth profile is affected by the long tail of FIB because shave-off scanning mode has the distinctive position of the primary ion beam against the sample. In this study, we acquired the different shave-off depth profiles by changing the speed of shave-off scan. Then, we estimated the approximate intensity profile of FIB by the change of the depth resolution of experimental depth profiles. By using this estimated intensity profile of FIB, we carried out the deconvolution to remove the influence of the long tails of FIB. As a result, this new data analysis method enables us to reconstruct highly precise calculated depth profile that reflects not the intensity profile of FIB but the true elemental distribution. [DOI: 10.1380/ejssnt.2010.237]

We have observed the laser wavelength (1064, 532, 355 nm) and power (2, 10, 20 nJ per pulse) dependence of field evaporation of carbonaceous material on a tungsten needle by a three dimensional atom probe (3DAP). Carbonaceous materials were deposited by gallium focused ion beam-chemical vapor deposition. Several peaks corresponding to low mass carbon compounds were highest at 355 nm. On the other hand, predominant gallium peaks were observed with 20 nJ per pulse. These results indicate that incident photon energy and tip temperature rising should be taken into consideration when using a femtosecond pulsed-laser atom probe. [DOI: 10.1380/ejssnt.2010.217]

Recently, laser pulses on a three-dimensional atom probe have been used to induce field evaporation. The advantages of laser-pulse atom probes are application to higher resistivity materials such as semiconductors and high mass resolution. Early studies of laser-pulse atom probes were performed with laser pulses of nanosecond duration. All evidence from these early studies and most recent studies using sub-picosecond laser pulses have indicated that the field evaporation of atoms by laser pulses occurred by a thermal pulsing mechanism. On the other hand, some recent experiments with sub-picosecond laser pulses have resulted in the proposal of athermal mechanisms (e.g., optical rectification) of field evaporation. Thus, the mechanism of field evaporation at the apex of a needle specimen by sub-picosecond laser pulses has not yet been established. We report the dependence of field evaporation voltage on the polarization angle of femtosecond laser pulses for metal specimens. [DOI: 10.1380/ejssnt.2009.70]

A wide-angle laser-assisted three-dimensional atom probe (3DAP) was developed, with a wide angle (0.75 sr) and short flight distance (110 mm) adopted to enlarge the analysis area of the tip. However, the short flight distance of ions resulted in the degradation of mass resolution. Therefore, flight path compensation was examined to improve the mass resolution in the 3DAP with a flight distance of 110 mm. With geometric compensation based on a simple concentric sphere model, the detected ions could be identified. By the compensation of the flight path for a small inclination on the microchannel plate (MCP) in the direction normal to the tip axis, the isotopes of detected ions were identified and high mass resolution was attained for a very short flight distance. [DOI: 10.1380/ejssnt.2009.35]

Differential photoelectron holography (DPH) is a new technique to overcome the forward-scattering problem of photoelectron holography (PH). DPH has the advantage to obtain three-dimensional atomic structure around each type of photoelectron emitter of solid surfaces and/or interfaces. However, DPH had been applied by using the synchrotron radiation (SR), not the laboratory-scale X-ray source. Therefore, we used a new rotating anode (dual target) in high-power X-ray source, along with two new artificial multilayer toroidal mirrors to obtain two X-rays at once, and realized DPH in a laboratory-scale experiment by applying DPH to the structure determination of TiO2 (110) surface. Copyright © 2008 John Wiley & Sons, Ltd.

We have studied the atomic structure of the surface and interface of VOX/TiO2 (110) by X-ray photoelectron diffraction (XPED). The TiO2 (110) crystal surface was cleaned by cycles of Ar+ sputtering followed by annealing. The TiO2 (110) crystal surface was deoxidized by annealing. Therefore, TiO2 (110) crystal surface was annealed in oxygen atmosphere. Vanadium oxides were deposited by two processes. In process A, vanadium was first deposited on the TiO2 crystal and then oxidized in an O2 atmosphere. In process B, vanadium was deposited in an atmosphere of low-pressure O2. We characterized the VOX ultrathin film grown on the TiO2 (110) surface by low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), and XPED. Finally the surface and interface structures of the VOX/TiO2 (110) were clarified by using the multiple scattering cluster model with spherical wave (MSC-SW) method and a reliability factor R(R factor). Copyright © 2008 John Wiley & Sons, Ltd.

It took several hours to obtain one X-ray photoelectron diffraction (XPED) pattern because XPED measurement requires repeated acquisition of XPS as a function of emission angle. The measurement time using our previous XPED system was too long to clarify the dynamics of epitaxial growth and catalytic reaction. In the present study, in order to minimize the measurement time, we improved the software used to control the XPED system. Then, by using the improved system, we obtained information on the structural changes during the heating process of an ion-bombarded silicon surface. Copyright © 2008 John Wiley & Sons, Ltd.

Three-dimensional atom probe (3DAP) equipped with a newly designed preset-type sample stage has been developed. This new type of sample stage can reduce the costs of constructing a 3DAP instrument, and this instrument consists of quite simple components because the complicated mechanism to make any desired adjustment is no longer required to be done in a vacuum. These advantages are expected to lead to the wider distribution of 3DAP. In addition, a wider range of applications is also expected in our equipment because the atoms can be field-evaporated by means of either high-voltage pulses or femto-second laser pulses. In this article, the performance of the pulse voltage mode and pulse laser mode are described and illustrated through the investigation of metals. Copyright © 2008 John Wiley & Sons, Ltd.

This paper reports the evaluation and operation of laser pulse assisted three-dimensional atom probe (3DAP). With wide angle acceptance using femto second pulse laser, high speed time to digital converter, and newly designed sample-extraction electrode integrated sample holder, we can get high performance, easy to treat and wide angle 3DAP. The change of the resolution in the application to pure metals such as Mo was observed when the laser condition (laser polarization and implied voltage) was changed. Copyright © 2008 John Wiley & Sons, Ltd.

The three-dimensional atom probe (3DAP) is one of the ways to image materials three-dimensionally on atomic scale. However, some technical issues in 3DAP are still unresolved. One of them is the rupture of a specimen that sometimes occurs when the atoms are field-evaporated at the apex of a needle specimen. This is caused by the high electric stress around the tip of the needle specimen. One way to reduce the stress is to enlarge the taper angle of the needle specimen. In this study, adapting this idea to 3DAP, we estimated the appropriate values of not only the taper angle of the needle specimen but also its diameter, length, radius of curvature, and distance between the tip and local electrode by simulation. Furthermore, we calculated the average value of field-induced stress on each plane for z-direction in the specimen. Copyright © 2008 John Wiley & Sons, Ltd.

We have studied the atomic structure of the surface and interface of VO2/TiO2(110) model catalyst by X-ray photoelectron diffraction (XPED). In this study, vanadium was deposited on the TiO2(110) surface in the oxygen atmosphere. We characterized the VO2 ultra-thin film grown on the TiO2(110) surface by low energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS), and XPED. As a result, VO2 ultra-thin film grown epitaxially on TiO2(110) was determined by using the multiple scattering cluster model with spherical wave (MSC-SW). Finally, we carried out the quantitative analysis by using the reliability factor R (R-factor) method and clarified the surface and interface structures of VO2/TiO2(110). [DOI: 10.1380/ejssnt.2008.272]

The growth of ultrathin Fe films of various coverages on Ge(1 1 1) at room temperature using molecular beam epitaxy (MBE) was studied via X-ray photoelectron diffraction (XPD or XPED) together with low energy electron diffraction (LEED) and X-ray photoelectron spectroscopy (XPS). All experimentally observed XPD patterns suggested local order structures of the Fe layers for all thicknesses studied. The short-range order of the resulting structures was found to be enhanced for thinner layers whereas the long-range order was gradually lost with increasing Fe thicknesses. At a very low coverage of 0.8 A Fe and Ge tend to react to the partly ordered structure in which Fe atoms were located in local environments similar to those for higher Fe coverages. Comparison of theoretical and experimental XPD patterns, along with XPS results, showed that intermixing between Fe and Ge occurred during the pseudomorphic growth with a stacking fault near the interface for all Fe coverages under study. Nevertheless, small percentage of domains without the stacking fault was also found to coexist with those with the stacking fault by performing a quantitative analysis of a reliability factor R of the Fe2p pattern for 5.4 A. The orientation changes of the Ge2p and Ge3d XPD patterns with Fe thickness were unambiguously explained in terms of their different dependencies on the overlayer thickness due to the different inelastic mean free path lengths used in the simulations. Also, Fe got increasingly enriched in the grown layers with increased Fe coverage. The resulting structures and intermixing are discussed in detail.

We obtained the detailed compositional information of diesel and gasoline exhaust particles, and discussed the possibility of the classification into each emission source. The intensities of Ca + and hydrocarbons were relatively high in the TOF-SIMS spectrum of the gasoline exhaust particles. The secondary ions such as NH 4 + and Si(CH 3 ) 3 + were strongly detected from the diesel exhaust particles. From TOF-SIMS images of each type of exhaust particles, Ca + of the gasoline exhaust particles and Si(CH 3 ) 3 + of diesel exhaust particles were strongly detected from the large particles with diameter of 0.3 μm. From these results, the exhaust particles collected in the atmosphere near the traffic route can be classified by their origin by using TOF-SIMS information.

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.

Shave-off depth profiling completely differs from ultra shallow depth profiling and has an absolute depth scale and a 50 µm wide dynamic range. In this paper we report on shave-off depth profiling of a nano-device with a complex nano-structure consisting of dynamic random access memory and introduces an analytical tool for advancing of nano-devices.