AVS 53rd International Symposium
    Surface Science Tuesday Sessions
       Session SS-TuP

Paper SS-TuP21
Initial Stages of the Diffusion Barrier Formation on Semiconductors: Mechanism of Decomposition of Tetrakis-(dimethylamino)-titanium on Clean and Ammonia-modified Si(100) Surfaces

Tuesday, November 14, 2006, 6:00 pm, Room 3rd Floor Lobby

Session: Surface Science Poster Session
Presenter: J.C.F. Rodriguez-Reyes, University of Delaware
Authors: J.C.F. Rodriguez-Reyes, University of Delaware
A.V. Teplyakov, University of Delaware
Correspondent: Click to Email
Tetrakis-(dimethylamino)-titanium (TDMAT) is a deposition precursor for titanium nitride and titanium carbonitride diffusion barriers. In spite of its crucial impact for the interface formation, the reaction of TDMAT with the practically important Si(100) surface has not been understood. In this work, the mechanism of decomposition of TDMAT on clean and ammonia-pretreated Si(100) surface is investigated by a combination of X-ray photoelectron spectroscopy (XPS), thermal desorption, infrared spectroscopy, and density functional theory (DFT). Adsorption of TDMAT on a clean Si(100) substrate proceeds through weak dative bonding of its ligands. Decomposition of TDMAT on a clean Si(100) surface leads to the evolution of a complex mixture of products including methane, dimethylamine and hydrogen cyanide. A chemometric approach is used to identify and quantify these compounds. The decomposition processes are analyzed on a clean Si(100) surface and compared to the ammonia-modified surface. Specific surface reactive sites produced by ammonia adsorption and thermal decomposition on Si(100) substrate have been investigated computationally and identified spectroscopically. Several previously predicted structures existing on this surface at high temperature were confirmed experimentally and a novel surface structure relevant for nitrogen diffusion was proposed. Decomposition of TDMAT on ammonia-modified surfaces is experimentally observed to be more effective than on clean Si, which provides a way to change the surface energetics by pre-treating the surface. This approach is also applied to investigating the decomposition of TDMAT on a carbon-modified Si(100) surface.