AVS 45th International Symposium
    Electronic Materials and Processing Division Friday Sessions
       Session EM-FrM

Paper EM-FrM10
XPS Study of the Role of Ti and TiN Caps on the Cobalt / SiO@sub 2@ Interface

Friday, November 6, 1998, 11:20 am, Room 316

Session: Fabrication and Characterization of Semiconductor Device Layers
Presenter: T. Conard, IMEC, MAPFCA, Belgium
Authors: T. Conard, IMEC, MAPFCA, Belgium
E. Kondoh, IMEC, Belgium
W. Vandervorst, IMEC, Belgium
Correspondent: Click to Email
Continuous downscaling of devices features and increases in operation frequency of ICs requires a low electric resistance of interconnects to transistors. Due to its low resistivity, high thermal stability and small lattice mismatch with Si, the integration of CoSi@sub 2@ into ultra large scale ICs is becoming the main stream. The role of metal caps layer (Ti, TiN) on the Si/Co interface chemistry has already been described but its effect on insulation dielectric such as SiO2 has not yet been widely studied. In this study, a 20 nm Co film was grown on a 150 nm LPCVD SiO@sub 2@ and Ti or TiN top layers were deposited on the Co layer without breaking the vacuum. The samples were annealed for 90 sec at 850 C in N@sub 2@ ambient and the specimens were analyzed by X-ray Photoelectron Spectroscopy (XPS) in depth profile mode using Ar@super +@ sputtering. Significantly different depth profiles were obtained depending on the nature of the cap layer. The multilayer with a top TiN layer presents a profile corresponding to sharp interfaces with only a limited diffusion of Ti inside the Co layer and no differences in chemistry of the interfaces due to the annealing procedure. The Co depth profile has a very symmetric shape. On the contrary, the presence of a Ti cap layer induces very strong modification of the interface reactions. First, an important diffusion of the Ti is observed through the Co layer is observed and an accumulation of Ti occurs at the Co/SiO@sub 2@ interface. At the interface, Ti is observed in an oxidized form and reduces the SiO@sub 2@ top layer. The effect of the annealing temperature will also be presented.