Masanori Owari

DEVELOPMENT OF AN ION AND ELECTRON DUAL FOCUSED BEAM APPARATUS FOR THREE-DIMENSIONAL MICROANALYSIS

We are developing a novel three-dimensional (3D) microanalysis method by means of successive cross-sectional Auger mapping. In this method, a 3D elemental map will be obtained by repetition of the cross-sectioning of a sample using a gallium focused ion beam (Ga FIB) and Auger mapping of the cross section using an electron beam (EB). On the basis of this concept, an ion and electron dual focused beam apparatus was developed by combining a Ga FIB and a mass spectrometer with a scanning Auger microprobe. In this paper, we describe the concept and instrumentation of the dual focused beam apparatus. Two types of preliminary experiments; i) successive cross-sectioning of a microparticle (6.8 µm) and ii) successive cross-sectional sample current imaging of a bonding wire of an IC, demonstrated the capability to create flat analytical surfaces favorable for the 3D analysis with arbitrary shape and heterogeneity.

Quantitative analysis by submicron secondary ion mass spectrometry

In order to apply secondary ion mass spectrometry (SIMS) to quantitative analysis of submicron areas, we made a high‐spatial resolution SIMS (submicron SIMS) by combining a focused metal ion beam, a plane‐focusing mass spectrometer, and a multichannel parallel detection system. A 35 kV, 100 pA beam with diameter on the sample of <0.1 μm was used. During measurements, this high‐current density ion beam can destroy the sample with a large sputtering rate when slowly rastered. This causes rapid changes in both absolute and relative intensities of secondary ions. In our system, a 120‐channel parallel detector covers the 1:2 mass range of m/e dispersion. By using this submicron SIMS, quantitative factors in the analysis of microstructures on the surface were investigated. Sputtering yield and, consequently, secondary ion intensity depend largely upon the angle between the primary beam and the sample surface just under the beam irradiation; such topographic effects distort the quantitative results. In order to ...

Photoelectron diffraction effects in XPS angular distributions from GaAs(110) and Ge(110) single crystals

Abstract Angular distribution measurements of XPS intensities have been made for various spectral lines from GaAs(110) and Ge(110) single-crystal surfaces. Observed angular distribution curves (ADCs) showed steep intensity variations and sharp peaks due to X-ray photoelectron diffraction (XPED) phenomena. The effects of the type of transition process (photoelectron or Auger), electron kinetic energy and crystal structure on the XPED patterns were examined. Considerably different ADC patterns were observed for high-energy photoelectrons and Auger electrons and for low-energy photoelectrons. ADCs for Ga 3d, As 3d and Ge 3d showed almost the same patterns for scans of the type [110] → [100] → [1 1 0], but they showed substantially different patterns for [110] → [11 1 ] → [00 1 ] scans. These features correspond well with the structural characteristics of GaAs and Ge crystals. A discussion of the applicability of XPS angular distribution measurements to the geometric analysis of crystal surfaces is presented.

Angular resolved x-ray photoemission study of defects induced by ion bombardment on the TiO2 surface

Angular resolved X-ray photoelectron spectroscopy was used to study single crystal TiO2 surfaces where defects (that is Ti3+ ions) were created by Ar+ ion bombardment. An estimate of the thickness of the disordered layer was obtained by an analysis of the attenuation of the oscillations in the polar photoelectron diffraction patterns of the Ti 2p signal. The intensity of the Ti3+ /Ti4+ signal ratio as a function of the electron collection angle was analyzed by means of simple structural models. The best agreement of calculations and experiment was obtained with a model which assumes that partially reduced titanium is present mainly in the subsurface region.

High spatial resolution 3D analysis of materials using gallium focused ion beam secondary ion mass spectrometry (FIB SIMS)

Abstract The sharpness and high density of focused ion beams (FIB) enable micromachining of materials. When a gallium FIB is used as a primary beam for secondary ion mass spectrometry (SIMS), 2D analysis with submicron resolution is easily achieved. In situ combination of micromachining and high spatial resolution analysis brings a new field of microbeam analysis of materials. The gallium FIB SIMS apparatus was developed by combining a FIB and a plane-focusing mass analyzer equipped with a multichannel ion detection system (120 channel). Both a high-spatial resolution and a large sputtering rate are realized. Multielement parallel detection has a great advantage for obtaining precise distribution of elements in microstructure samples. In this paper, a new type of 3D analysis and depth profiling technique is introduced and applied to single particle analyses. A spatial resolution of 50 nm for 3D analysis and a depth resolution up to 5 nm were realized by using these methods.

Analysis of surface composition and internal structure of fly ash particles using an ion and electron multibeam microanalyzer

Abstract An ion and electron multibeam microanalyzer was developed and applied to analysis of coal fly ash particles. Employing ordinary TOF-SIMS function, it was found that the surface of the fly ash particles mainly consisted of Ca, C, Si, and Na. A special analysis technique with a combination of “shave-off” cross-sectioning and TOF-SIMS mapping of the cross section was adopted to a single fly ash particle in order to reveal the internal structure. It was found that the particle had a cenosphere structure. TOF-SIMS mapping of the cross-sectioned particle clarified that the particle had the following layers, outermost layer (Na, Si, Ca-rich), shell (Na-rich), inner shell (Na, Si, Al-rich).

X-ray photoelectron diffraction (XPED) patterns from: III-V compound mixed crystals (Ga1-xAlxAs AND GaAs1-yPy). Comparison of experiment and single scattering calculations

Abstract X-ray photoelectron diffraction (XPED) measurements, together with single scattering calculations, were made for two III—V group compound semiconductor mixed crystals (Ga 1- x Al x As(110) and GaAs 1- y P y (001)). Each pair of photoelectrons excited at equivalent atomic sites in the crystal (Ga 3 d and Al 2 p in Ga 1 - x Al x As, and As 3 d and P 2 p in GaAs 1 - y P y ) showed essentially the same XPED patterns. Single scattering calculations reproduced the observed XPED patterns fairly well. An obvious site dependence of XPED patterns was observed in both the experimental and calculated results. These results clearly show that, for a given kinetic energy, XPED patterns mainly depend on the site of emitter atoms in the crystal, not on the species of emitter atoms. Thus, XPED measurements can be used for crystal site determinations in a fingerprint manner.

Development of ion and electron dual focused beam apparatus for high spatial resolution three-dimensional microanalysis of solid materials

We constructed an ion and electron dual focused beam apparatus to develop a novel three-dimensional (3D) microanalysis technique. In this method, a Ga focused ion beam (Ga FIB) is used as a tool for successive cross sectioning of the sample in the “shave-off” mode, while an electron beam (EB) is used as a primary probe for Auger mapping of the cross sections. Application of postionization with EB to Ga-FIB secondary ion mass and two-dimensional (2D) elemental mapping with Ga-FIB-induced Auger electrons are also in the scope of the apparatus. The 3D microanalysis was applied to a bonding wire on an integrated circuit (IC). A series of EB-induced sample current images of the successive cross sections were obtained as a function of the cross-sectioning position. This result showed the capability to realize the 3D Auger microanalysis. Two-dimensional elemental mapping with Ga-FIB-induced Auger electrons was realized for the first time on the IC surface. Its applicability to surface analysis was evaluated.

X-ray photoelectron diffraction of SrTiO3

Abstract X-ray photoelectron diffraction patterns of Sr3d, Ti2p 1 2 and O1s X-ray photoelectron peaks are measured for SrTiO3(001) single crystals. The reproducibility of the diffraction patterns are discussed. The photoelectron diffraction peaks are successfully assigned by the forward scattering of photoelectrons by the atomic potential near the emitter atom in the lattice. The strong diffraction peaks are coincident with the internuclear axes in the single crystals.

A Chemical-State-Discriminated XPED Study on Structure of Thin CaO Layer Formed by Electron Bombardment Heating on CaF2(111)

CaF2 in the surface layer with a thickness of a few nanometers was converted to CaO by electron bombardment heating above 300°C, but CaO was not formed by the lamp heating. This conversion is thought to occur by electron bombardment to the sample surface during heating. Furthermore, it was found by chemical-state-discriminated X-ray photoelectron diffraction (XPED) measurements that CaO grew epitaxially on CaF2(111). The crystallographic orientation of the CaO epitaxial layer was directly determined from the analysis of XPED patterns.