AVS 49th International Symposium
    Thin Films Wednesday Sessions
       Session TF-WeA

Paper TF-WeA2
Growth and Structure of Al@sub 2@O@sub 3@/W Nanolaminates Fabricated Using Atomic Layer Deposition Techniques

Wednesday, November 6, 2002, 2:20 pm, Room C-101

Session: Atomic Layer Deposition - Applications of ALD
Presenter: Z.A. Sechrist, University of Colorado
Authors: Z.A. Sechrist, University of Colorado
F.H. Fabreguette, University of Colorado
O. Heintz, Universite de Bourgogne
S.M. George, University of Colorado
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Nanolaminates are expected to have unique thermal, mechanical, electrical and optical properties. Atomic layer deposition (ALD) methods have been used to grow Al@sub 2@O@sub 3@/W nanolaminates. Al@sub 2@O@sub 3@ ALD is based on the binary reaction: 2Al(CH@sub 3@)@sub 3@ + 3H@sub 2@O --> Al@sub 2@O@sub 3@ + 6CH@sub 4@. W ALD is based on the binary reaction: WF@sub 6@ + Si@sub 2@H@sub 6@ --> W + 2SiF@sub 3@H + 2H@sub 2@. To optimize Al@sub 2@O@sub 3@/W nanolaminate growth, W ALD has been examined using in situ quartz crystal microbalance (QCM) investigations. The QCM measurements reveal extremely linear W growth versus the number of binary reaction cycles. The W deposition rates are dependent on substrate temperature and Si@sub 2@H@sub 6@ exposures. The W ALD deposition rates vary from ~4 Å per AB cycle at 177°C and ~10@super 5@ L Si@sub 2@H@sub 6@ exposures to ~7 Å per AB cycle at 325°C and ~10@super 7@ L Si@sub 2@H@sub 6@ exposures. QCM studies of Al@sub 2@O@sub 3@/W nanolaminate growth reveal that the nucleation of W ALD on Al@sub 2@O@sub 3@ surfaces is a critical variable. Atomic force microscope studies indicate that the shortest nucleation times yield the lowest surface roughnesses for the Al@sub 2@O@sub 3@/W nanolaminates. W ALD nucleation times were shortened by increasing Si@sub 2@H@sub 6@ exposures. Al@sub 2@O@sub 3@ nucleation times were shortened by finishing the W growth with a WF@sub 6@ exposure. The structural analysis of these nanolaminates using transmission electron microscopy (TEM) yields very well-resolved superlattice structures. X-ray reflectivity (XRR) measurements confirmed very conformal Al@sub 2@O@sub 3@ and W deposition with low interfacial roughness. Secondary ion mass spectrometry (SIMS) gave chemical confirmation of alternating oxide/metal nanolayers with regularly repeating AlO@super +@ and W@super +@ ion signals as the ion beam milled through the nanolaminate.