Ion Bombardment Of Thin Films Research Articles

High Energy Ion Bombardment of Thin Films: From Platinum on Silicon to Platinum Silicide

The effect of high energy ion bombardment on ultra-thin Pt films deposited on silicon substrates was investigated. The changes caused by the bombardment were studied using a combined characterization approach, consisting of X-Ray Photoelectron Spectroscopy (XPS) and electrochemical measurements. The chemical sensitivity of XPS helped determine locally the nature of the film after bombardment, which transitions to platinum silicide, as demonstrated by a dramatic evolution of the Pt4f and valence band spectra. Cyclic voltammetry provided the average electrochemical response of the entire sample surface (1 cm2) in contact with an acidic solution. This technique is particularly sensitive to the evolution of the platinum undergoing bombardment. Initially showing a typical Pt electrochemical response, the film undergoes an irreversible transformation, leading to the absence of any metallic platinum on the surface after a sufficient bombardment dose, based on the absence of electrocatalytic activity. This study highlights the complementarity of XPS and electrochemical characterization. The platinum silicide fabrication technique described here may also be of interest for electronics applications, since platinum silicide contacts are used in a variety of thin film devices.

Ion bombardment of SiO 2/Si and Si measured by in situ X-ray reflectivity

We have used in situ energy dispersive X-ray reflectivity to measure the evalution of structure and morphology during ion bombardment of thin films of SiO 2 on Si and of clean Si. The high resolution of this technique (0.3 nm in film thickness and 0.04 nm in surface roughness) makes it possible to resolve thin film structures that are difficult to detect by other means, while the reasonably short acquisition time (< 1000 s per spectrum) makes it possible to study the kinetics of layer modification. We present measurements of low-energy (600–1000 eV) ion bombardment which demonstrate the ability of the technique to resolve very shallow (< 4 nm) implanted regions. We also compare the kinetics of surface roughening by reactive H ions and inert Xe ions on an amorphous oxide (SiO 2) with that on a crystalline semiconductor (Si, Ge). H ions were observed to smoothen SiO 2 surfaces that were made rough by prior Xe ion bombardment. Details of the energy dispersive technique and its benefits for in situ measurements are described.

An Apparatus for the Production and Ion Bombardment of Thin Films†

This communication describes a versatile apparatus for the production of thin polycrystalline metallic films under conditions of high purity. The apparatus includes facilities for film preparation by evaporation and cathodic sputtering and for ion bombardment of the films under the same conditions of purity as obtained during preparation. The films can also be annealed before and after ion bombardment, although at this stage of the programme these facilities have not been fully used. Electrical conductivity measurements of the films can be made in situ and some preliminary data on the effects of ion bombardment on the electrical conductivity of thin metallic films are reported.