AVS 45th International Symposium
    Thin Films Division Thursday Sessions
       Session TF-ThA

Paper TF-ThA5
Roughness Measurements With X-Rays Using an Out-Of-Plane Scattering Geometry

Thursday, November 5, 1998, 3:20 pm, Room 310

Session: Ex-situ Characterization of Thin Films
Presenter: J.J. Kelly IV, University of Wisconsin, Madison
Authors: J.J. Kelly IV, University of Wisconsin, Madison
J. Con Foo, University of Wisconsin, Madison
J.F. MacKay, University of Wisconsin, Madison
M.G. Lagally, University of Wisconsin, Madison
Correspondent: Click to Email
Surface and interface morphology plays a dominant role in fields ranging from thin-film magnetism to integrated-circuit production. Of the several techniques that can be used routinely for quantitative determination of the surface morphology, diffuse X-ray scattering provides the widest dynamic range in terms of the lateral scale of roughness that can be sampled, from sub-Angstrom to many micrometers. The use of a grazing-incidence geometry enhances surface sensitivity. In investigations to assess the influence of surface and interface roughness in giant-magnetoresistive films, we have measured the diffusely scattered intensity of soft X-rays (~1 keV) from rough surfaces and interfaces of Si, Co, Ni, and their combinations, using a non-conventional approach, an out-of-plane scattering geometry. An out-of-plane measurement is not limited by the shadow edge of the sample surface, and thus it samples a much wider range of reciprocal space and hence a much larger range of roughness wavelengths than a conventional in-plane rocking curve. We use the Born approximation and the distorted wave Born approximation to fit the data. The bandpass of our experiment allows us to extract all the relevant roughness parameters: the mean square roughness @sigma@, the correlation length @xi@, and the roughness exponent h. We have measured a roughness of bare highest-quality polished silicon wafers of less than 0.5 @Ao@, lower than can be measured by AFM or other techniques. Comparisons to rocking curves measured on the same samples in the same chamber will be presented to show the capabilities of this method. Roughness measurements on epitaxial sputter-deposited Co-on-Cu films will also be shown and, as time permits, compared to magnetic properties of these films. This work is supported by AFOSR and NSF. The Synchrotron Radiation Center is supported by the NSF.