Auger depth profiles of TiN/Ti films in submicron contact holes: A comparison of collimated and uncollimated deposition processes

Abstract

Auger depth profiles are used to compare sputtered Ti, reactively sputtered TiN, and TiN/Ti bilayer films in submicron (0.8 and 0.4 μm) contact/via holes, deposited with and without a collimator. Samples were cleaved and mounted to minimize difficulties associated with the sputter profiling of and data acquisition from recessed features. The Ti and N concentrations were calculated with a subtract-and-weight routine which uses dN(E)/d(E) peak-to-peak intensities. Transmission electron microscopy film thicknesses measurements were used to confirm that the sputter rates were comparable for the various sample mounting geometries. The thickness of films deposited on the contact base, relative to those on the surrounding oxide was greater when the collimator was used. For 0.8 μm contacts, the film thickness ratio obtained using the collimator was nearly twice that obtained with the uncollimated deposition (0.5 versus 0.25 for TiN; 0.8 versus 0.6 for Ti). The benefits of the collimator, for obtaining good coverage of the base of the hole, are more pronounced in smaller geometries. For films deposited with the collimated on 0.4 μm contacts the film thickness ratio was ten times that for films deposited without the collimator (0.4 versus 0.05 for TiN, 0.35 versus 0.03 for Ti). There was no evidence of variations in the TiN stoichiometry for films deposited in confined geometries versus the surrounding oxide for either deposition configuration. There was an increase in the depth of surface oxidation for the Ti-only film deposited on the sidewalls using the collimator. Shadowing effects cause an increase in film porosity when the direction of collimated metal flux is parallel to the sample surface. On exposure to atmosphere, this porosity allows oxidation below the surface of the film.

Parallel Particle Simulations of Thin-Film Deposition

“…The angular distributions are also normally distributed about the perpendicular angle of deposit. Some modifications to these distributions are achieved in the laboratory by filtering wide-angled particles (collimation) (Hoener et al, 1994) or substrate biasing (directional sputtering) (Rossnagel et al, 1991). For our simulations, we allow both fixed and randomly generated values for the incident values of energy and angle.…”

3D characterization of a W/TiN/ Ti/Si contact structure using MULSAM

“…There have also been several di †erent methods of sample preparation used in previous Auger analyzes of impurities or barrier materials at the bottom of contact holes. 1,3,4,6,8,9 The common aim in preparing such samples for Auger analysis is to provide unrestricted lines of sight to both the excitation source and the electron energy analyzer. In addition, the spectroscopy is most easily interpreted if the electrons leaving the surface are not scattered on the sidewalls of contact holes before reaching the entrance aperture of the analyser.…”