Growth characteristics of Mn silicate barrier layers on SiO&lt;inf&gt;2&lt;/inf&gt;

P Casey,A.P Mccoy,J Bogan,J.G Lozano,P.D Nellist,G Hughes

doi:10.1109/iitc.2012.6251652

Abstract

Synchrotron radiation photoelectron spectroscopy (SRPES) is used to investigate the in-situ formation of ultra thin Mn silicate copper diffusion barrier layers on SiO 2 . It was shown that high temperature annealing results in the growth of Mn silicate, the stoichiometry of which was calculated to be MnSiO 3 . SRPES results also show that the interaction of metallic Mn with SiO 2 is self limiting at high temperature. In a separate experiment the role of oxygen in determining the extent of the interaction between the deposited Mn and the SiO 2 substrate was investigated. Using X-ray photoelectron spectroscopy (XPS) it has been shown that a metallic Mn film (~1 nm) cannot be fully converted to Mn silicate following vacuum annealing to 500°C. Transmission electron microscopy (TEM) analysis suggests the maximum MnSiO 3 layer thickness obtainable using metallic Mn is ~1.7 nm. In contrast, a ~1 nm partially oxidized Mn film can be fully converted to Mn silicate following thermal annealing to 400°C, forming a MnSiO 3 layer with a measured thickness of 2.6 nm. TEM analysis also clearly shows that MnSiO 3 growth results in a corresponding reduction in SiO 2 layer thickness. Based on these results it is suggested that the presence of Mn oxide species at the Mn/SiO 2 interface facilitates the conversion of SiO 2 to MnSiO 3 .

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