Epitaxial growth of MgO/TiN multilayers on Cu K.H. Kim a, b , D.P. Norton a, * , D.K. Christen b , C. Cantoni b , M. Paranthaman c , T. Aytug b a University of Florida, Department of Materials Science and Engineering, PO Box 116400, Gainesville, FL 32611, United States b Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge, TN 37831, United States c Oak Ridge National Laboratory, Chemical Science Division, Oak Ridge, TN 37831, United States article info Article history: Received 14 May 2008 Accepted 3 October 2008 Keywords: Oxides Epitaxy Pulsed-laser deposition Superconductivity Diffusion barriers Copper Titanium nitride Magnesium oxide PACS: 81.15.Fg 84.71.Mn 81.05.Je 85.40.Ls abstract The growth of epitaxial MgO/TiN multilayer films on (001) Cu has been investigated. In particular, epitaxial structures were grown on (001) Cu layers that were epitaxial on (001) SrTiO 3 . X-ray diffraction and reflection high-energy electron diffraction indicate that the multilayer structures are epitaxial on the (001) Cu surface. The motivation is the use of crystalline MgO/TiN multilayers as a diffusion barrier to both copper and oxygen. MgO/TiN multilayers are potentially useful as diffusion barriers for Cu inter- connects on semiconductors as well as for superconducting wires based on the epitaxial growth of cuprate superconductors on biaxially textured copper. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction The integration of materials that are chemically incompatible in terms of processing ambient, interfacial reactions, or adverse contamination is important for a number of technologies. For the specific case of copper, applications where barrier layers are needed to chemically separate the metal from other materials include semiconductor interconnects [1–4] and coated high-temperature superconducting tapes [5,6]. In the case of semiconductor metal- lization, the push for high circuit density and low RC time delays has made copper the material of choice for interconnects due to its high resistance to electromigration and low resistivity as compared to Al [7]. Unfortunately, Cu is known to rapidly diffuse into SiO 2 and Si. This obviously degrades the electrical properties of devices [8] creating the need for intermediate layers that provide a barrier to Cu diffusion [9]. It is also desirable to identify barrier layer structures that are stable against oxygen as well as Cu diffusion, given that functional complex oxides [10], such as dielectrics or ferroelectrics, may be integrated on device platforms in future technologies [11]. Another area where barriers layers for metals are important is in high-temperature superconducting tapes based on epitaxial superconducting films on biaxially textured metals [12]. In cuprate superconductors, the superconducting critical current density in thin films can be extremely high due to defect- or nanoparticle- induced flux pinning [13], but will be severely limited by the presence of large angle grain boundaries [14,15]. For the technology known as Rolling-Assisted Biaxially Textured Substrates (RABiTS) [16,17], the large angle grain boundaries are eliminated via epitaxial growth of superconducting films on metal tapes that are crystal- lographically textured via thermo-mechanical processing [18]. High-temperature superconducting (HTS) biaxially textured coated conductors hold significant promise for the development of a superconducting wire technology functional at liquid nitrogen temperatures (64–77 K) [19–23]. To date, this technology has focused on epitaxial YBa 2 Cu 3 O 7 (YBCO) films [24] deposited on biaxially textured Ni or Ni-based alloy substrates. With many Ni alloys, there are potential limitations associated with ferromagnetic hysteretic losses in the substrate. The use of diamagnetic Cu tapes as the base metal substrate circumvents this limitation [25]. An obvious issue with Cu is the oxidation of the metal substrate. * Corresponding author. Tel.: þ352 846 0525. E-mail address: dnort@mse.ufl.edu (D.P. Norton). Contents lists available at ScienceDirect Vacuum journal homepage: www.elsevier.com/locate/vacuum 0042-207X/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.vacuum.2008.10.002 Vacuum 83 (2009) 897–901