Aluminum oxide and tungsten atomic layer deposition on polymers and nanoparticles

Christopher Alvin Wilson
Abstract & Cover

Thin solid films are standard components in a wide variety of technologies such as integrated circuits, wear resistant coatings, energy cells, displays, and micro-electromechanical devices. This work explores four principle technology needs in thin film materials research: inorganic gas diffusion barriers on organic polymer encapsulation, thin nucleation layers to seed film deposition, metal conduction layers on dielectric polymer particles incorporated into bulk electromagnetic interference shield structures, and low oxygen content transition metal coatings on cobalt nanoparticles incorporated into bulk hardmetal. The fabrication of these nanometer dimensioned thin film structures requires the atomic level thickness control and conformability of the Atomic Layer Deposition (ALD) method. An Al2O3 ALD inorganic diffusion barrier on organic polymers is fabricated and characterized to elucidate the general mechanism of deposition on porous polymer substrates. The model developed for inorganic thin film growth on organic polymers is based on extensive Quartz Crystal Microbalance (QCM) studies and involves precursor diffusion into the near surface region, nucleation cluster formation, cluster coalescence to form an impermeable barrier, and subsequent thin film growth above the surface. A W ALD conductive layer is fabricated and characterized on polymer films and polymer particles. X-Ray Reflectivity (XRR) and X-Ray Photoelectron Spectroscopy (XPS) studies reveal that W ALD is greatly facilitated by an Al2O3 ALD nucleation layer and resistivity measurements affirm the conductive nature of thin tungsten films on polymers. A W ALD coating is fabricated on hydrogen reduced cobalt nanoparticles and cobalt thin films and a model of the oxygen content of the particles is developed based on geometry, profilometry, oxygen analysis, and XPS studies. This work demonstrates that Al2O3 and W ALD thin films are ideal components in thin film technologies with polymers and nanoparticles. 

Source of Information
University of Colorado Boulder
(Boulder, USA)
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