AVS 50th International Symposium
    High-k Gate Dielectrics and Devices Topical Conference Monday Sessions
       Session DI-MoA

Invited Paper DI-MoA7
Growth, Characterization and Thermal Stability of High-K Gate Stacks

Monday, November 3, 2003, 4:00 pm, Room 317

Session: High-k Dielectric Stability
Presenter: E.L. Garfunkel, Rutgers University
Authors: E.L. Garfunkel, Rutgers University
T. Gustafsson, Rutgers University
D.G. Starodub, Rutgers University
S. Sayan, Rutgers University
L.V. Goncharova, Rutgers University
D. Vanderbilt, Rutgers University
X. Zhao, Rutgers University
R.A. Bartynski, Rutgers University
T. Nishimura, Murai Project, Japan
Y.J. Chabal, Rutgers University
Correspondent: Click to Email
We describe recent results using medium energy ion scattering (MEIS), soft x-ray photoemission (SXPS), inverse photoemission (IPES), electron microscopy (TEM), infrared spectroscopy (FTIR), electrical methods and first-principles calculations to examine high-K gate dielectrics and their interfaces with silicon and metal layers. MEIS has proven extremely helpful in presenting accurate elemental depth profiles of high-K films on Si, Ge and GaAs, especially related to the problem of interface composition. Our isotopic labeling results give new insight on oxygen incorporation and diffusion in high-K films. In selecting an alternative (to SiO2) gate insulators, many parameters in addition to dielectric constant and thermal stability must be considered, including the barrier heights for tunneling. Our SXPS and IPES experimental results are complemented by first-principles density functional calculations to study the properties of the different crystalline phases of HfO2 and ZrO2. It is found that the band gap, barrier height and dielectric response of these two materials are phase dependent. The densities of states are calculated and compared to various experimental measurements. The thickness, layered structure, and crystal phase of the as-deposited and annealed films have been studied by diffraction (XRD), x-ray adsorption (XAS), MEIS and TEM. Critical electrical and materials changes occur during post-processing at elevated temperature. We discuss these changes, including the decomposition of the films in reducing environments in the 900-1100°C range. Finally, FTIR results on initial surface reactivity and ALD/CVD film growth are presented. The authors would like to acknowledge productive interactions with colleagues at Agere, IBM, NCSU and Stanford. We also acknowledge the SRC/Sematech FEP Center and the NSF for financial support.