Reaction mechanisms in aluminum-indium tin oxide ohmic contact metallization with Co and Ni barrier layers for active-matrix-display applications

Reaction mechanisms within aluminum-indium tin oxide (Al-ITO) metallization schemes were investigated in this work using Xray photoelectron spectroscopy and X-ray diffraction. Examination of A1-ITO, aluminum-nickel-indium tin oxide (Al-Ni-ITO), and aluminum-cobalt-indium tin oxide (Al-Co-ITO) interfaces reveals that considerable atomic rearrangement at the ITO interface with Al or with barrier layer transition (CO or Ni) metals occurs due to reaction. Metal-oxygen bonds in crystalline ITO are broken and the interface is rearranged. In Al-Co-ITO stacks, reduced intermetallic species were detected at the Co-ITO interface. In Al-Ni-ITO stacks, such species were not detected at the Ni-ITO interface, although Al3Ni formed at the Al-Ni interface. These reactions within metallization stacks are important because they determine the electrical quality of ITO contacts with Al alloy data lines in polysilicon thin film transistor displays. (C) 1999 The Electrochemical Society. S0013-4651(98)08-069-0. All rights reserved.