AVS 52nd International Symposium
    Electronic Materials and Processing Tuesday Sessions
       Session EM2-TuM

Invited Paper EM2-TuM1
Characterization of High-@kappa@ Materials using High Resolution Ion Backscattering

Tuesday, November 1, 2005, 8:20 am, Room 312

Session: High-k Dielectric Characterization
Presenter: T. Gustafsson, Rutgers University
Authors: T. Gustafsson, Rutgers University
E. Garfunkel, Rutgers University
L.V. Goncharova, Rutgers University
R. Barnes, Rutgers University
D. Starodub, Rutgers University
Correspondent: Click to Email
Understanding the thermodynamics and kinetics of film growth during fabrication of high-@kappa@ gate stacks is vital to establish atomic level control of interfacial layers and to minimize defects. Annealing such films in different atmospheres may lead to diffusion and reactions with significant consequences on the electrical properties. Ion beam methods, in particular medium energy ion scattering (MEIS), are non-destructive, high resolution (sub-nm) tools for quantitative characterization of buried layers and interfaces. An attractive feature is the possibility to use isotope tracing, which allows a study not just of the structures of such ultrathin films, but also of the processes responsible for their formation. We will discuss some key materials issues relevant to films and interfaces in next-generation highly-scaled CMOS gate stack structures as investigated using ion beams. As one example, we will contrast the behavior of Hf and Ce oxides on Si during annealing in an oxide atmosphere. The Hf based system shows evidence for oxygen exchange, which could be suppressed by mixing the oxide with SiO@sub 2@. Little SiO@sub 2@ interfacial growth was observed. This reaction saturates with time and appears to be enhanced after film recrystallization. Annealing in nitrogen results in reduced oxygen incorporation and exchange. In contrast, Ce silicates exhibit rapid interface growth upon oxygen exposure. Materials changes occur in the ultrathin films and at the various interfaces during growth and processing at elevated temperature that strongly affect device properties. Changes in oxide and silicate interface composition and thickness, phase mixing and crystallization within the film, and film decomposition will be discussed also for high-@kappa@ films on Ge and GaAs. In general the native oxides on these materials are less stable than those of Si, leading to different high-@kappa@ layered structures and interface composition.