This Letter reports the observation of hysteresis in the vortex pinning in a superconductor-ferromagnetic epitaxial nanocomposite consisting of fcc Gd particles incorporated in a Nb matrix. We show that this hysteretic pinning is associated with magnetic reversal losses in the Gd particles and is fundamentally different in origin to pinning interactions previously observed for ferromagnetic particles or other microstructural features.

Abstract. Grain size determination in advanced metallization structures requires a technique with resolution ~2nm, with a high signal-to-noise ratio and high orientation-dependant contrast for unambiguous identification of grain boundaries. Ideally, such a technique would also be capable of high-throughput and rapid time-to-knowledge. The Helium Ion Microscope (HIM) offers one possibility for achieving these aims in a single platform. This article compares the performance of the HIM with Focused Ion Beam, Scanning Electron and Transmission Electron Microscopes, in terms of achievable image resolution and contrast, using plan-view and cross-sectional imaging of electroplated samples. Although the HIM is capable of sub-nanometer beam diameter, the low signal-to-noise ratio in the images necessitates signal averaging, which degrades the measured image resolution to 6-8nm. Strategies for improving S/N are discussed in light of the trade-off between beam current and probe size, accelerating voltage, and dwell time.

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In this paper the possible application of ion-induced Auger electron spectroscopy (IAES) for 3D chemical tomography using the focused ion beam (FIB) is discussed. In conventional electron-induced Auger electron spectroscopy (EAES), an electron beam with energy 1-10kV is used to excite inner-shell (core) electrons of the solid. An electron from a higher electron energy state de-excites to this hole and the extra energy is then transferred to another electron, i.e. the Auger electron, which has a characteristic energy and serves to identify the excited atom [e.g. 1, 2]. In IAES, on the other hand, very large excitation cross sections can occur by promotion of inner shell electrons through crossing of molecular orbitals. Such excitation processes have been described by Barat and Lichten [3] for bi-particle gas phase collisions. In addition to excitation of incident or target atoms, there would also be a substantial momentum transfer from the incident to the target atoms, which may cause the target atom to sputter off leading to the possibility of decay while the atom is either in motion in the solid or is traveling in vacuum after sputtering [e.g. 4]. As a result there are differences between spectra induced by electrons and ions. In particular, interpretation of the ion-induced Auger spectra requires separate consideration of both excitation and decay processes.We have successfully integrated a state-of-the-art mass-filtered FIB (Orsay Physics) with a PHI Versaprobe XPS instrument. The concentric hemispherical analyzer (CHA) of the Versaprobe is then utilized to measure the kinetic energy of the Auger electrons induced by the ions from a gold-silicon alloy source. IAE spectra of some of the elements in third-row of the periodic table, namely Na, Mg, Al, Si, and the ones in the fourth-row, namely Ti, V, Cr, Mn, Fe, Co, Ni and Cu acquired using Si ++ and Au + incident ions will be presented and discussed (An example for Cr is shown in Figure 1, left). As a result of energetic collisions between the incident and target atoms, in addition to plasmon excitations, Auger electrons from both colliding particles are generated and detected. The efficiencies of Auger electron generation by ion impact from these elements, acquired under the same conditions, are compared with each other. The elements on the third row of periodic table in particular show narrow peaks emanated mainly from the decay of excited atoms. For heavier elements, however, the increase of fluorescence yield by increasing atomic number results in reduction of atomic contribution to the spectrum. Nevertheless, by using optimized analyzer settings, sharper peaks with higher signal to noise ratio are also achieved for these elements that sets the foundation for chemical tomographic imaging using IAE spectroscopy.

As the features of interest in state-of-the-art integrated circuits (ICs) are getting smaller the ability of scanning electron microscopes (SEMs) to see things in detail in semiconductor metrology is worsening. One important reason is the formation of an electron beam induced contamination layer that seriously deteriorates image contrast and resolution. It can even be found in SEMs with so-called clean vacuum systems (no oil pumps). Different sources of the environmental contamination, including the sample itself have been discussed elsewhere [1]. This contamination layer is commonly attributed to the polymerization of low molecular weight hydrocarbon (HC) molecules on the surface of the sample following interaction with the electron beam. One way of removing them from the system is to promote their removal by oxidation processes [2]. In the current study we have evaluated the efficacy of this approach based on the use of an Evactron NanoLab 600) equipped with an Energy Dispersive X-ray Spectrometer (Princeton Gamma-Tech, Si(Li)). The dual beam FIB/SEM was selected because of its usefulness in examining the grain structure of sub-100nm copper interconnects. One drawback in observing grain structure is the flatness of the finished surfaces prepared by FIB, which significantly reduces the variation in the secondary electron (SE) yield associated with any topography on the surface. Unlike the transmission electron microscopes where the diffraction contrast is usually the dominant mechanism for grain contrast, in SEMs the contrast is a result of point to point variation in the SE yield. This can be due to surface topography, chemical composition or crystallographic effects. Since in the case of FIB-prepared copper interconnects, the surface is flat and there is no chemical variation from grain to grain, the contrast will depend primarily on variations in crystallographic effects which are generally small compared to the other two and thus maybe difficult to observe. While our ultimate goal is to improve contrast in cross sectional images of microelectronic interconnects, our initial experiments involve measuring contamination rate buildup on a bare silicon substrate. The carbon buildup in a square raster 2.5 μm on a side was measured as a function of time both before and after the use of the Evactron ® de-contaminator. To avoid the possible effect of different currents in the before and after data, a graphite standard sample was used and the ratio of carbon peak intensity from HC layer to graphite standard is presented (k-ratio). The results shown in Figure 1, clearly indicates that there is little to no carbon buildup after using the de-contaminator. As an additional observation, the carbon intensity on the square produced in the first experiment, was remeasured after cleaning with Evactron