Deposition of silicon-based thin films with atmospheric-pressure plasmas

Plasma enhanced chemical vapor deposition (PECVD) is a unique technique to produce coatings with characteristics suitable for a wide range of applications, including electronics, aerospace, and medicine. Despite the technology is well-established at low pressure (LP), atmospheric pressure (AP) PECVD is receiving a lot of attention due to the absence of expensive vacuum equipment and the possibility of industrial on-line processing. Organosilicon compounds, such as tetraethyl orthosilicate (TEOS) and hexamethyldisiloxane (HMDSO), are excellent precursors for atmospheric pressure plasma polymerization since the chemical-physical characteristics of the deposited thin films can be tailored by properly controlling process parameters. Despite the large body of works on the subject available in the scientific literature, there is still a limited understanding of the fundamental mechanisms of atmospheric pressure plasma polymerization of organosilicon precursor.

The present work will cover both applicative and fundamental aspects of the deposition process, discussing the following topics:

1) Deposition of nanostructured coatings exhibiting antibiofilm and anticlot properties, considering both the case of 2D samples for in-vitro testing and the case of 3D catheter samples for in-vivo studies;

2) Production and characterization of surface gradient coatings by single-step deposition of HMDSO;

3)Mechanisms of atmospheric pressure plasma polymerization of organosilicon precursors, investigated through laser induced fluorescence (LIF), two-photon absorption LIF (TA-LIF) and Rayleigh scattering;

4) Aerosol-plasma polymerization of organosilicon fluorinated precursors for the production of antimicrobial coatings;

5) Evaluation of the power to precursor ratio as a control parameter for aerosol-plasma polymerization at atmospheric pressure.