AVS 51st International Symposium
    Electronic Materials and Processing Monday Sessions
       Session DI-MoA

Paper DI-MoA1
Metal Nitride Gate Electrode Effects on Dielectric Properties of HfO2 and Hf-doped TaOx High-k Gate Dielectrics

Monday, November 15, 2004, 2:00 pm, Room 304B

Session: High-k Dielectrics: Electronic Properties
Presenter: Y. Kuo, Texas A&M University
Authors: Y. Kuo, Texas A&M University
J.-Y. Tewg, Texas A&M University
J. Lu, Texas A&M University
P. Majhi, Sematech
G. Bersuker, Sematech
Correspondent: Click to Email
High-k gate dielectrics with appropriate gate electrodes are critical to future MOS device performance. Metal oxides, such as hafnium oxide and various doped tantalum oxides, are promising high-k materials. Since polysilicon has many practical limits for the high-k gate electrode application, e.g., undesired interface layer formation and dopant diffusion, other conductive materials are being actively sought for this purpose. Metal nitrides are possible candidates because they can be easily prepared by the sputtering method, are usually difficult to react with the adjacent oxide, and are good diffusion barriers. In this paper, authors investigated the influence of various types of metal nitride electrodes, i.e., molybdenum nitride MoN, tungsten nitride WN, and tantalum nitride TaN, on electrical characteristics of MOS capacitors composed of a high-k dielectric layer of hafnium oxide or Hf-doped tantalum oxide. Hafnium oxide was deposited by atomic layer deposition ALD and the doped tantalum oxide was deposited by reactive sputtering. Dielectric properties, such as EOT, leakage current, flatband voltage, metal work function, and interface state density, were studied. Process parameters, such as the annealing temperature and atmosphere were varied for their influence on the electrical properties. The interface and bulk film material properties were characterized with ESCA, XRD, and TEM. Dielectric properties were dramatically influenced by the nitride electrode and the process parameters. We are going to discuss the cause of the difference with respect to material and interface layer changes during the process.