AVS 49th International Symposium
    Surface Engineering Tuesday Sessions
       Session SE+TF-TuA

Paper SE+TF-TuA4
Profile Coatings and Their Applications

Tuesday, November 5, 2002, 3:00 pm, Room C-111B

Session: Systems Design of Functional Coatings
Presenter: C. Liu, Argonne National Laboratory
Authors: C. Liu, Argonne National Laboratory
L. Assoufid, Argonne National Laboratory
A. Macrander, Argonne National Laboratory
G. Ice, Oak Ridge National Laboratory
J. Tischler, Oak Ridge National Laboratory
K. Zhang, Illinois Institute of Technology
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We report a method of profile coating to achieve a certain pre-selected thickness profile of a thin film coating using dc magnetron sputtering. In profile coatings, the substrate is passed over a contoured mask at a constant speed to obtain a desired profile along the direction perpendicular to the substrate-moving direction. The shape of the contour depends on the desired profile and the thickness distribution directly above the gun at the substrate level. Four-inch-diameter Si wafers were coated through a 100 x 152 mm@super2@ aperture on the top of the shield can. The thickness distribution was then obtained using a spectroscopic ellipsometer with computer-controlled X-Y stages. A model has been developed to fit the measured thickness distribution. The relative thickness weightings are then digitized at every point 1 mm apart for the entire open area of the aperture. When the substrate is moving across the shield can during depositions, the film thickness is directly proportional to the length of the opening on the can along the moving direction. By equating the summation of relative weighting to the required relative thickness at the same position, the length of the opening at that position can be determined. By repeating the same process for the whole length of the required profile, a contour can be obtained for a desired thickness profile. The contoured mask is then placed very close (~1 mm) to the substrate level on the shield can opening. The number of passes and the moving speed of the substrate are determined according to the required thickness and the growth rate calibration. This method of profile coating has been applied to coat laterally graded W/C multilayers for tunable x-ray double-monochromator and x-ray fluorescence detection applications. It has also been applied to coat Au on a cylindrical mirror to obtain an elliptical mirror for x-ray focusing applications. Test results for these applications will be presented.