AVS 57th International Symposium & Exhibition
    Thin Film Wednesday Sessions
       Session TF+EM-WeM

Paper TF+EM-WeM3
Non-destructive Depth Profiles of Hafnium Silicate Films by Angle-Resolved and Variable-Kinetic Energy XPS

Wednesday, October 20, 2010, 8:40 am, Room Dona Ana

Session: High K Dielectrics for Si Electronics
Presenter: C. Weiland, University of Delaware
Authors: C. Weiland, University of Delaware
N. Lorenz, University of Delaware
R. Opila, University of Delaware
Correspondent: Click to Email
High dielectric constant, or high-k films are currently being employed in semiconductor devices. Hafnium silicate (HfxSi(1-x)O2­) films are a promising material system for such applications, as they combine the high dielectric constant of HfO2 with the high stability against crystallization of SiO­2. The HfxSi(1-x)O2/Si interface must be defect free as defects at this interface can create charge centers which decrease channel mobility. Atomic layer deposition (ALD) is frequently used to deposit high-k films, and provides excellent thickness control and conformality by reacting only one saturating layer of reactant at a time. This work focuses on studying the composition and interface quality of HfxSi(1-x)O2 films deposited by ALD using novel silicon precursors and water as the oxidizer. Films are analyzed using non-destructive depth profiles by angle-resolved and variable-kinetic energy X-ray photoelectron spectroscopy (ARXPS, VKE-XPS). In ARXPS, the effective probe depth is varied by changing the takeoff angle between surface and detector. As a complementary technique, VKE-XPS provides depth profiles by adjusting the incident X-ray energy, and thus the corresponding inelastic mean free path of the photoemitted electrons. VKE-XPS also allows the ability to probe deeper into films than conventional lab-based sources, providing the possibility of analyzing thicker films or entire gate stacks. Using these techniques, we have studied the composition and interface quality of HfxSi(1-x)­O2 films deposited using various Si precursors. The presence of charge at the interface manifests itself as shifts in the energy of the photoelectron peaks. Using this data, we can determine charge at the high-k/silicon interface as well as measure band offsets.