Depth selective XANES study of swift heavy ion irradiation effects in metal/Si systems

Abstract

Swift heavy ion induced intermixing of thin metallic layers of Ti, Fe and W with Si has been studied. A single specimen containing 3.0 nm thick layers of the three metals at different depths in Si, ensures a more reliable comparison of the mixing efficiencies of the three systems. X-ray reflectivity and X-ray standing wave analysis has been used to obtain the concentration profile of the three metals before and after irradiation with 100 MeV Au ions. While Ti and Fe exhibit considerable mixing with Si after an irradiation fluence of 1×1013 ions/cm2, W profile is only slightly broadened. XANES measurements under X-ray standing wave conditions have been able to differentiate between the structure of the center of a layer from that of the interfacial region. It is found that irradiation results in only a further disordering of the central as well as interfacial regions of the W layer. In contrast, the Fe layer gets completely mixed with Si and forms an amorphous silicide. © 2003 Published by Elsevier B.V.