Remco Theodorus Johannes Petrus Geurts

High-quality sample preparation by low kV FIB thinning for analytical TEM measurements.

Focused ion beam specimen preparation has been used for NiTi samples and SrTiO3/SrRuO3 multilayers with prevention of surface amorphization and Ga implantation by a 2-kV cleaning procedure. Transmission electron microscopy techniques show that the samples are of high quality with a controlled thickness over large scales. Furthermore, preferential thinning effects in multicompounds are avoided, which is important when analytical transmission electron microscopy measurements need to be interpreted in a quantitative manner. The results are compared to similar measurements acquired for samples obtained using conventional preparation techniques such as electropolishing for alloys and ion milling for oxides.

Evaluating focused ion beam induced damage in soft materials

Focused ion beam (FIB) microscopy uses Ga(+) ions to remove material from a sample for a variety of imaging and preparation techniques. While considerable work has examined the effects of FIB exposure on a number of materials, optimized FIB conditions for use with softer polymeric materials are yet to be determined. In this report we use phase contrast AFM to measure local changes in the elastic modulus of polycarbonate surfaces parallel to a sectioning FIB at varying beam energies. We show that polycarbonate surfaces exposed to lower FIB energies appear stiffer than the bulk material whereas surfaces exposed to the higher beam energies of up to 25keV are more representative of the bulk material. Energy dispersive spectroscopy (EDS) indicates that the polymer surfaces become stiffer because of Ga(+) implantation from the FIB. Our experimental observations are supported by computer simulations showing an increase in the residual Ga(+) concentration near-surface at lower FIB energies. A high energy FIB is therefore shown to be less invasive, producing a surface more representative of the bulk material, than using low energy FIB when sectioning polymers.

A New In-situ Broad Ion Beam, With Energy Range 1 – 500 eV

The interest in low energy ion beams (typically Ar at 50 – 500 eV), is increasing and finds applications in surface clean up, such as removal of hydrocarbons and oxide layers and in fields related to reactive ion etching. Also the removal of Ga + ions and the amorphous layer in a TEM lamella prepared with FIB is interesting. Within the environment of an SEM or DualBeam a new ion source has been constructed. The ion source is based on a narrow gas channel, in which the atoms are converted into ions using direct ionization by the primary electron beam of the system. This local ionization is primarily driven by the electron ionization cross-section of the gas involved, as a function of the primary electron beam energy. Opposite the channel is a surface at potential -V and at gap distance d (Figure 1). The resulting field (V/d) between this surface and the channel-output, will induce ion acceleration towards the surface: in this way a stationary broad beam of ions with well-defined energy is created. In this set-up the ion energy and the ion current are decoupled parameters and hence can be chosen each within their practical boundaries. In case the gas type is changed, the ionization only scales with the respective cross-section of the applied gas. The behavior of ion source has been simulated with both Opera simulation software and GEANT4 [1], using the actual geometrical set up and physical data as input. This allows to study the influence of the most relevant parameters, including the geometry and to compare it to measured values -using a method described belowwith the aim to optimize the source for its application.