화학공학소재연구정보센터
Journal of Vacuum Science & Technology B, Vol.12, No.3, 1394-1401, 1994
Auger Depth Profiles of Tin/Ti Films in Submicron Contact Holes - A Comparison of Collimated and Uncollimated Deposition Processes
Auger depth profiles are used to compare sputtered Ti, reactively sputtered TiN, and TiN/Ti bilayer films in submicron (0.8 and 0.4 mum) 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 mum 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 mum 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.