Ar ion milling

Figure 7. A uger surface spectrum of a commercial soda-lime-silica glass before corrosion (a) after corrosion, for 1 h (b), 37°C and compositional profile obtained by AES-Ar ion milling of the corroded glass in (b) and spectra obtained at various depths for 1 h, 37°C (c). (Reproduced, with permission, from Ref. 1. Copyright 1979, Books for Industry.)...

In SIMS the surface of the solid is bombarded with a primary beam of ions and this produces secondary ions from the surface which can be detected and quantified with a Mass Spectrometer. The very process by which SIMS analysis is obtained produces its own milling of the surface and consequently no additional Ar-ion milling is required as with AES and ESCA. 

In ESCA the surface of the material is irradiated with low energy monochromatic x-rays ejecting electrons. The energies of the ejected electrons can be correlated to the species as well as the shell from which the electron was ejected. Thus compositional as well as information concerning the chemical state of the species in the material can be obtained. ESCA also appears to do less damage to the surface during analysis than does AES. In order to perform a compositional profile Ar ion-milling is required. 

Xu et al. [40] have very recently prepared alumina with U-shaped pores of a uniform diameter (40-50 nm) whose bottoms were opened in a controlled way by Ar -ion milling. Fig. 4 shows an AFM image of the resulting pores after short-term ion milling, which produced pores 8-14 nm wide. By contrast, long-term ion milling led to a hole diameter equal to nanopore diameter, indicating that the U-shaped bottom cap was etched away completely. 

Recently there has been a report of the use of Ar+ ion milling (500 eV) to open the bottom cap in the anodized alumina using a normal ion milling machine. The rate of milling can be controlled by the ion beam current density (generally <1 mA cm ) and also the incident angle. The nominal milling rate is 100 A min at normal incidence for a current density of 1 mA cm [12]. 

The alloying process was observed through the changes of the X-ray diffraction patterns of milled powders. And the microstructures of the sintered compacts were observed by TEM. The samples for TEM observation were prepared by Ar ion milling. 

Dry Etch Resistance. Polyvinylnaphthalene and its derivatives were reported to be highly resistant to dry etching ( 9 ). Under Ar ion milling or CCl sputter etching conditions, etch rates for poly(2-vinylnaphthalene) were found to be about two-thirds of those for polystyrene or novolak resin resists. To find relationships between etch resistance and chemical structure, etch rate measurements for various metal-free polymers were made under Ar or C>2 ion beam incidence. It was found that the etch rate under ion bombardment depends linearly on N/(Nc -N0), where N denotes the total number of atoms in a monomer unit, Nc and N0 are the number of carbon atoms and the number of oxygen atoms in a monomer unit, respectively ( ). The dependence on "N/(NC-N0) factor" indicates that... 

In the early days of TEM, sample preparation was divided into two categories, one for thin films and one for bulk materials. Thin-films, particularly metal layers, were often deposited on substrates and later removed by some sort of technique involving dissolution of the substrate. Bulk materials were cut and polished into thin slabs, which were then either electropolished (metals) or ion-milled (ceramics). The latter technique uses a focused ion beam (typically Ar+) of high-energy, which sputters the surface of the thinned slab. These techniques produce so-called plan-view thin foils. 

The basic requirement is a diffusion-pumped chamber attached to an ion gun. The ion gun is filled with high-purity inert gas such as Ar. This gas is accelerated between two electrodes with a high potential difference. This ionizes the gas and a beam of focused and collimated gas particles is aimed at the specimen surface. Modern electronics allows very precise manipulation of the ion beam in several ways. Most ion milling machines are singlebeam systems where one surface of the specimen is thinned. Alternatively, double-sided machines are also available where there are two ion beams focused on either side of the same specimen that is milled from both the top and bottom surfaces. 

Figure 9.8. Influence of reactive gases on ion milling of delicate materials. The top figure shows an InP specimen after regular Ar-ion etching. Islands of metallic indium are formed by this process. The bottom figure shows same material thinned by iodine-jet-assisted ion etching (CAIBE). The islands are not formed and actual nanostructural features can now be studied. (Adapted from Ref. 30.)...

In ion-milling, we demonstrated to achieve fine magiKtic coliunn arrays with a diameter of 40 to 100 nm and a space of 100 nm using 200 eV Ar... 

Inasmuch as most of the 1,3-dialkylimidazolium ILs have extremely low vapor pressure and relatively high viscosity at room temperature, in situ TEM observations in dispersed ILs can be carried out. Indeed, this method was applied for size and shape in situ analysis of various transition-metal NPs dispersed in the ILs (see Table 6.1). The size and shape determined by this in situ technique are the same as those obtained with NPs mixed with an epoxy resin distributed between two silicon wafer pieces and dried at 50 °C. In these cases the samples were pre-thinned mechanically to a thickness of about 20 nm and then ion milled to an electron transparency using 3kV Ar ion beams. 

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