The ion beam sputtering of a metallic Ti and a ceramic TiO 2 target by bombardment with oxygen ions was investigated systematically. Emphasis was put on the properties of the secondary particles emitted from the target, namely, the angular distribution of the sputtered Ti and the energy distribution of the secondary ions. Ion energies of 0.5, 1.0, and 1.5 keV and incidence angles of 0°, 30°, and 60°were used. The angular distribution of the flux of sputtered Ti particles was determined by measuring the thickness of TiO 2 films that were deposited under emission angles in the range between −40°and +80°. An empirical formula was used to describe the angular distribution as a superposition of an isotropic and an anisotropic cosinelike function. Increasing the ion energy or decreasing the ion incidence angle leads to a more isotropic emission of the sputtered Ti particles. The mass and energy distribution of the secondary ions were measured using an energy-selective mass spectrometer. The most prevalent ion species are O + , O 2 + , Ti + , and TiO +. Ion energy and sputtering geometry, i.e., the combination of an ion incidence angle and an emission angle, were found to have a strong influence on the energy distribution of the secondary ions.

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Ion current density distributions, mass spectra, and ion energy distribution functions (IEDFs) for the use of Ar and mixtures of Ar/He and Ar/Ne in an RF broad beam ion source have been measured as a function of the extracted ion beam current and the applied RF-power. For the measurements, an array of Faraday probes and an energy-selective mass spectrometer have been used. Regardless of the gases or gas mixtures used, a broadening of the ion current density profile is measured at constant grid voltages with increasing RF-power. The IEDFs of all species are also dependent on the applied RF-power and show a bimodal shape with an increasing energy shift for a higher RF-power. The data show a significant contribution of charge exchange processes after the ions left the ion beam source. Besides ions of the process gas, additional species of ions originating from the erosion processes of the ion beam source, can be found in the mass spectrum. The measurements show that the operating conditions of the ion source have a significant influence on the beam properties and thus can also affect the results of ultraprecise ion beam-assisted processes.

Process stability and reproducibility are essential for highly precise manufacturing with reactive ion beam etching (RIBE) in optics industry. Therefore, the ion beam source characteristic must be well known. For this study, a Kaufman-type broad beam ion source operated with CHF3 and O2 is characterized with energy selective mass spectrometry and Faraday measurements. These results are compared with etching experiments on SiO2, Si, and AZ®1505 photo resist. The influence of the source setup and process conditions on ion beam composition, ion energy distribution, and the etch selectivity are discussed. It was found that etch selectivity applying different ion beam currents at a fixed feed gas composition correlate with resulting ion beam composition. Due to a change in ion beam composition, selectivity also changes with the total volumetric mass flow of the feed gas at a fixed ion beam current and constant mixing ratio of CHF3 and O2.