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

Abstract

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.