Investigation of the interfacial structure of ultra-thin platinum films using X-ray reflectivity and X-ray photoelectron spectroscopy

• Published in: Thin solid films 2000-09, Vol.372 (1), p.94-103
• Main Authors: Solina, D.M, Cheary, R.W, Swift, P.D, Dligatch, S, McCredie, G.M, Gong, B, Lynch, P
• Format: Article
• Language: English
• Subjects: Applied sciences; Condensed matter: structure, mechanical and thermal properties; Electron beam evaporation; Exact sciences and technology; Interface structure and roughness; Interfaces; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Magnetron sputtering; Metals. Metallurgy; Multilayers; Physics; Platinum; Solid surfaces and solid-solid interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin films; X-Ray photoelectron spectroscopy; X-Ray reflectivity
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/S0040-6090(00)01044-0

Ultra-thin films of platinum deposited on highly polished 100 silicon have been investigated using X-ray reflectivity (XRR) and X-ray photoelectron spectroscopy (XPS) as part of a study on the interface structure of multilayers used for X-ray mirrors. In this paper results are presented for films deposited by electron beam evaporation and by DC-magnetron sputtering. The reflectivity was fitted by assuming an intermediate platinum silicide layer exists between the platinum and the silicon. XPS data clearly confirmed the existence of such a platinum silicide layer. According to the XRR data this layer was estimated to be approximately 10 Å thick for e-beam samples and approximately 30 Å thick for magnetron samples. For e-beam films the fitted density for the platinum silicide layer was found to decrease from 16.4 g·cm −3 for a nominal 80 Å film down to 2.65 g·cm −3 for a nominal 20 Å film. For magnetron sputtered films the fitted density was always within the range of 6.1–6.8 g·cm −3. The fitted density of the platinum layer from the e-beam results was always within 5% of the density of bulk platinum whereas for the magnetron sputtered films the density decreased uniformly with decreasing film thickness for films with a nominal thickness less than 30 Å. The XPS data show that the magnetron deposited platinum penetrates through the native oxide layer and into the silicon substrate to a far greater degree than the e-beam deposited platinum.