Photoemission study of carbon depletion from ultralow-κ carbon doped oxide surfaces during the growth of Mn silicate barrier layers

In this study Mn silicate (MnSiO₃) barrier layers were formed on ultralow dielectric constant carbon doped oxide (CDO) surfaces, using both metallic Mn and oxidized Mn films, in order to determine the growth method best suited to preventing the depletion of carbon from the CDO surface. Using x-ray photoelectron spectroscopy it has been shown that the deposition of metallic Mn and partially oxidized Mn (MnO_x, where x < 1) films on CDO surfaces results in the formation of both MnSiO₃ and an 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. In a separate experiment, it was shown that the interaction of a fully oxidized Mn (MnO_y, where y ≥ 1) layer on CDO resulted 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 the CDO surface in the presence of metallic Mn and will not occur through the interaction of the CDO with fully oxidized Mn layers. It has also been shown that the growth of MnSiO₃ layers on the CDO is self-limited by the availability of additional oxygen, beyond that found within the CDO layer, which is in agreement with previous studies on SiO₂ surfaces.