Photoemission study of the growth of Mn silicate barrier layers on ultra low-k carbon doped oxide surfaces

In this study Mn silicate (MnSiO₃) barrier layers were formed on ultra low dielectric constant (ULK) carbon doped oxide (CDO) surfaces, using both metallic Mn and oxidized Mn films. Using x-ray photoelectron spectroscopy (XPS) it has been shown that deposition of metallic Mn and partially oxidised Mn (MnO_x where x <; 1) films on CDO surfaces results in the formation of both MnSiO₃ and a Mn carbide species within the barrier layer region. Analysis suggests that Mn carbide species are formed through the depletion of C from the CDO structure, which may increase the dielectric constant of the CDO. It is also shown that the interaction of a fully oxidised Mn (MnO_y where y ≥ 1) layer on CDO results in the growth of a MnSiO₃ barrier layer free from Mn carbide, metallic Mn and Mn oxide. These studies indicate that Mn carbide is only formed on CDO surface in the presence of metallic Mn. Finally, the growth of MnSiO₃ layers on CDO is shown to be self-limited by the availability of additional oxygen, beyond that found within the CDO layer.