IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Dielectrics Tuesday Sessions
       Session DI-TuA

Paper DI-TuA8
Core-level Photoemission of High-K Dielectrics on Si Substrates

Tuesday, October 30, 2001, 4:20 pm, Room 130

Session: High K Dielectrics III
Presenter: J.E. Rowe, Army Research Office
Authors: J.E. Rowe, Army Research Office
M.D. Ulrich, North Carolina State University
R.S. Johnson, North Carolina State University
T.E. Madey, Rutgers University
G. Lucovsky, North Carolina State University
Correspondent: Click to Email
High resolution soft X-ray photoelectron spectroscopy (SXPS) with synchrotron radiation is used to study the interface of device quality ultrathin gate oxides of Al, Ta and Al-Ta alloys. Our present studies were performed on thin oxides grown plasma-enhanced CVD. After growth samples were further processed by rapid thermal annealing for 30 sec at temperatures near ~ 900ºC. Our photoemission measurements were performed with synchrotron radiation at the National Synchrotron Light Source (NSLS) located at Brookhaven National Laboratory using beamline U4A which has a total instrumental resolution of better than 0.1 eV. Some data were collected at lower resolution (~0.2 eV) in order to increase data collecting efficiency for better sampling depth at higher photon energies (near 200 eV). We find that our data can be well described by an ultrathin ~5 Å interface layer of SiO2 with a graded transition to Al and/or Ta oxides. We have studied a number of samples prepared as described above and find that the interface peak energies relative to the Si-2p peak are 0.81 eV, 1.75 eV, 2.47 eV, and 3.60 eV for the Si+1, Si+2, Si+3, and Si+4 peaks respectively. No evidence of sub-oxides were found for either Al or Ta species. The total concentration of Si-suboxide derived from SXPS data is dependent on the uniformity of the SiO2 interfacial layer as well as data modeling, i.e., fitting of the data; both will be discussed.