Etching of native silicon oxide on the silicon surface using ultraslow multicharged Arq+ (q > 1) ions is investigated. As opposed to "kinetic sputtering'' using singly charged argon ions (Ar1+), oxide removal using multicharged ions is accomplished primarily by a "potential sputtering'' mechanism. The ion dose needed to obtain complete oxide removal for different ion charge states is determined. It is demonstrated that by using ultraslow multicharged Arq+ ions instead of singly charged ions with higher kinetic energy the native oxide can be physically removed, i.e., without any chemical interactions, essentially with no damage to the Si surface and subsurface region. (C) 2003 The Electrochemical Society.

Ultraslow single- and multicharged ions (USMCI) have small kinetic energy compared with their potential energies. They can be used for surface preparation at room temperature, to engineer the top atomic layers of surfaces without modifying the substrate below, in processes such as ultrathin film growths, etching, deposition, or nanostructures fabrication. The energy for the reaction is brought to the surface through the USMCI potential energy, which can be controlled by varying the ion charge. The USMCI kinetic energy is so small that they do not penetrate below the surface. We have used various USMCI under low pressures of O2 (between 10−9 and 5×10−6 Torr) to grow ultrathin films of SiO2 on Si wafers, from 0.3 to 2.3 nm with a resolution of 0.1 nm and a uniformity of ±0.1 nm. To evaluate the layers and optimise this process, we have analysed the surfaces by Fourier transform infrared spectroscopy, Auger electron spectroscopy, spectroscopic ellipsometry, transmission electron microscopy, X-ray photoelectron spectroscopy and surface charge analysis.

We have used ultra-slow multicharged ions in ultra-high vacuum with a low partial pressure of O2 to grow ultra-thin layers (0.3 to 2.0 nm) of SiO2 on silicon. The advantage of using ultra-slow ions is that they interact with the surface only through their potential energy, not their kinetic energy, so they do not penetrate below the surface, avoiding implanted-induced damages to the substrate. This paper presents several analysis we have performed to qualify these ultra-thin SiO2 layers, such as Fourier transform infrared spectroscopy–attenuated total reflection, Auger electron spectroscopy, X-ray photoelectron spectroscopy, spectroscopic ellipsometry and surface charge analysis. The oxidation process was monitored in situ and in real time using visible light emitted during the irradiation, and the thickness of the SiO2 layers could be controlled. We plan to used these ultra-thin SiO2 layers in next generation MOS gate dielectric stack, as a buffer layer between the channel in silicon and a high-k dielectric.

The availability of highly charged ion sources (electron cyclotron resonance or electron beam ion source) led in the last decade to many new scientific discoveries in various fields of atomic, solid state, and plasma physics. This article will review some of the most exciting results obtained in the field of the interaction of highly charged ions on surfaces in fundamental physics (hollow atom properties, mechanisms of electron captures and losses above, below, or at surface interactions…) as well as in applied physics (surface modifications, lithography, etc.). The deceleration and monochromatization of the ion beams delivered by the ion sources will be discussed in the framework of their use in the study of the ion surface interactions.

This talk briefly reviews the atomic properties of the hollow atoms and presents recent results on the interaction of highly charged ions with surfaces.