AVS 52nd International Symposium
    Thin Films Tuesday Sessions
       Session TF-TuM

Paper TF-TuM5
Laterally Graded Films and Multilayers Using Atomic Layer Deposition with a Slit Doser and Substrate Translation

Tuesday, November 1, 2005, 9:40 am, Room 306

Session: Atomic Layer Deposition - Oxides
Presenter: F.H. Fabreguette, University of Colorado
Authors: F.H. Fabreguette, University of Colorado
S.M. George, University of Colorado
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Laterally graded multilayers have a bilayer spacing that continuously changes versus spatial position. These graded multilayer structures are important for x-ray collimation and x-ray focusing. Recently, optimized W/Al@sub2@O@sub3@ superlattices grown using atomic layer deposition (ALD) displayed an excellent x-ray reflectivity (XRR) of 96% at @lambda@=1.54 Å. To obtain laterally graded W/Al@sub2@O@sub3@ multilayers, the normal conformality of ALD must be circumvented by preventing ALD on the entire substrate. Laterally graded multilayers can be fabricated using a slit doser to localize reactant delivery in a viscous flow gas stream. The substrate is then translated relative to the slit doser with a magnetic linear translator. Since the viscous flow entrains the reactants and moves them downstream, substrate translation upstream of the slit doser prevents ALD on the entire substrate. A laterally graded Al@sub2@O@sub3@ ALD film was initially demonstrated by translating the substrate relative to the slit doser during Al@sub2@O@sub3@ ALD reaction cycles. Variable angle ellipsometry and XRR quantified a varying Al@sub2@O@sub3@ film thickness grown on a Si(100) wafer with a length of 6 inches. Changes in leakage current density and capacitance confirmed the Al@sub2@O@sub3@ thickness gradient. In addition, a laterally graded ZnO/Al@sub2@O@sub3@ multilayer was grown and characterized using XRR. The angle of the first Bragg peak revealed a bilayer spacing that changed as expected versus spatial position.