AVS 57th International Symposium & Exhibition
    Thin Film Tuesday Sessions
       Session TF-TuA

Paper TF-TuA1
Studying Roll-to-Roll ALD Process Conditions Using a Moving Substrate Under a Gas Source Coating Head

Tuesday, October 19, 2010, 2:00 pm, Room Ruidoso

Session: ALD/CVD: Surface Chemistry and Fundamentals
Presenter: R. Fitzpatrick, University of Colorado
Authors: R. Fitzpatrick, University of Colorado
Z.M. Gibbs, University of Colorado
S.M. George, University of Colorado
Correspondent: Click to Email
Continuous roll-to-roll ALD processing is currently being developed for economical and efficient ALD on polymer and other flexible substrates. One of the key implementations of roll-to-roll ALD was introduced by Kodak (D. H. Levy et al., Appl. Phys. Lett. 92, 192101(2008)). To understand the dependence of roll-to-roll ALD on process conditions, we have constructed a laboratory-scale apparatus featuring a fixed gas source coating head that sits in ambient above a moving substrate that is driven by a programmable stepper motor. The gas source coating head consists of a series of rectangular channels that spatially separate the ALD reactions. As the substrate moves under the gas source coating head, the channel sequence for each reactant is: precursor; exhaust; N2 purge; and exhaust. The gas source head was built for 1.5 ALD cycles. Using Al2O3 ALD as a model system, the gas source head has the trimethylaluminum (TMA) channel sequence in the middle and the water channel sequence on each side of the TMA. This design allows for the deposition of two Al2O3 ALD cycles during one complete back-and-forth translation of the moving substrate. A low conductance gap between the precursor and exhaust channels allows for nearly “static” reactant exposures and prevents intermixing of the reactants. A higher conductance gap was machined into the gas source head between the exhaust and purge channels to create a “high flow” entrainment region that further isolates the precursor channels. The spacing between the gas source head and substrate is fixed and can be controlled with micron precision. This new apparatus can test how roll-to-roll ALD depends on the gap spacing, substrate speed, gas flow rates, and pressure difference between reactant and purge channels. An understanding of these process parameters will be necessary for the successful implementation of continuous, large scale roll-to-roll ALD.