IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Electronics Wednesday Sessions
       Session EL-WeM

Paper EL-WeM7
On the Use of Angle-resolved XPS for Resolving Composition Structure of Ultrathin Inhomogeneous Oxide Layers

Wednesday, October 31, 2001, 10:20 am, Room 124

Session: Si Surface Dynamics and Reactions
Presenter: T. Conard, IMEC, Belgium
Authors: T. Conard, IMEC, Belgium
H. De Witte, IMEC, Belgium
W. Vandervorst, IMEC, Belgium
J. Petry, IMEC, Belgium
R. White, Thermo VGScientific, UK
K.S. Robinson, Thermo VGScientific, UK
Correspondent: Click to Email
With the downscaling of electronic, the industry faces a large number of challenges. Among those, layers with an EOT lower than 1nm have to be engineered for the gate oxide. The materials considered can be silicon oxynitride, ZrO@sub 2@, Al@sub 2@O@sub 3@ as a single layer or as multistack. One common characteristic of all these films is there very limited thickness (a few nm at most) and the inhomogeneous distribution of elements throughout the stack. These films challenge thus most of the analysis techniques used for determining the layer structure and composition such as SIMS. For very thin layers, XPS is a possible alternative to sputtering techniques as it allows a non-destructive analysis through the whole film. The development of angle resolved XPS instruments with the ability to acquire spectra simultaneously over multiple angles should also give the possibility to retrieve the layer composition as a function of depth. This work concentrates on the interpretation of such ARXPS data and its application as an alternative and complementary technique to SIMS profiling. Particular in our experiments is the simultaneous collection of up to 16 emission angles (using a Thermo VG Scientific ThetaProbe) which provides unparalleled capabilities to reconstruct non-homogenous depth profiles in very thin layers. We will present results showing that small differences in the nitrogen distribution (near surface, in film, interfacial) inside thin (~3.5 nm) SiON layers can be determined using simultaneous ARXPS. In addition, the technique can also be used to understand the strong modification observed in the profiling of ZrO@sub 2@/SiO@sub 2@/Si stacks using Ar+ ions at energies between 500 eV and 3keV. The depth profiles reconstructed from the ARXPS provide information on the redistribution of Zr and O in the ion bombarded film allowing to interpret these modifications in terms of oxygen preferential sputtering and sputtering induced oxygen diffusion in the ZrO@sub 2@ layer.