AVS 58th Annual International Symposium and Exhibition
    Thin Film Division Thursday Sessions
       Session TF2-ThM

Paper TF2-ThM12
Deposition and Modeling of Nanoscale Organic Porous Polymeric Layers and their Characterization with Visual and Electrical Methods

Thursday, November 3, 2011, 11:40 am, Room 110

Session: Modeling and Analysis of Thin Films
Presenter: Florian Schamberger, Munich University of Applied Sciences, Germany
Authors: G. Franz, Munich University of Applied Sciences, Germany
F. Schamberger, Munich University of Applied Sciences, Germany
Correspondent: Click to Email
To act as long-term antibacterial coating on the interior of hollow implants like artificial bladders or flexible pipes which can act as urethrae, silver layers have to be partly protected against aggressive solutions of the human body, e.g. urine or gall. One of these organic polymers is poly-p-xylylene, commonly known as polyparylene. In order to control this process of dissolution from metallic silver to silver ions which is responsible for the toxic impact, the layers should exhibit an adjustable hole density. This requires the growth control of very thin layers between zero and about 250 nm. By application of the conventional Gorham method, only thicknesses beyond 2 microns are accessible. We present a completely new method to control the growth of these very thin layers with defined porousity for which exact knowledge of vapor pressure and evaporation rate is required which have been measured and modeled using statistical rate theory (SRT) [1]. Applying a digital evaluation procedure of the micrographs gained with AFM, the hole density is correlated with the breakdown voltage and the capacitance which can both easily applied to the samples. Whereas the coating of open surfaces is controlled by flow, this mechanism is not applicable for coating of narrow holes which takes place as a diffusive process with losses due to deposition. In a series of experiments, the growth behavior in thin, narrow pipes with an aspect ratio between 10 and 30 has been obtained, and a theoretical model is presented which reflects the crossover of these two transport mechanisms as function of chamber pressure and temperature. [1] C.A. Ward, and G. Fang, Phys. Rev. E59, 429 (1999)