| AVS 56th International Symposium & Exhibition | |
| Thin Film | Wednesday Sessions |
| Session TF-WeA |
| Session: | ALD/CVD: Novel Applications, Mechanical Properties |
| Presenter: | A.M. Coclite, University of Bari, Italy |
| Authors: | A.M. Coclite, University of Bari, Italy G. Ozaydin-Ince, Massachusetts Institute of Technology F. Palumbo, University of Bari, Italy R. d'Agostino, University of Bari, Italy K. Gleason, Massachusetts Institute of Technology |
| Correspondent: | Click to Email |
Deposition techniques of multiple dense, inorganic layers alternated with soft, organic ones are widely investigated for several technological applications. Generally, a combination of two different deposition techniques is employed for deposition of organic/inorganic multilayered coatings. The possibility of a single-chamber vacuum-deposited system may greatly simplify the production and allows the quicker and cheaper roll-to-roll deposition. Here we propose a new technique for multilayer deposition, consisting of coupling initiated and plasma enhanced CVD, maintaining the same organosilicon precursor and the same reactor configuration.
Multilayer coatings comprised of alternating inorganic (silica-like) and organic (organosilicon polymer) layers were deposited using hexavinyldisiloxane (HVDSO) as precursor. The organosilicon polymers were deposited by initiated CVD (iCVD) at filament temperature of 280°C. The silica-like layers were obtained by Plasma Enhanced CVD (PECVD) applying RF power to the same filament used in the iCVD process. The multilayers were obtained through layer by layer deposition, switching from one technique to the other without venting the system.
Chemical and morphological characterization of the organic single layer showed that the iCVD of poly-HVDSO resulted in a very crosslinked film with high deposition rate, high Carbon content (79 % from XPS analysis) and very low roughness (0.7 nm). PECVD of the same monomer, when highly diluted in Oxygen, gave inorganic coating with a low content of OH terminal groups and high deposition rate. X-ray photoelectron spectroscopy (XPS) depth profile, ellipsometric characterization and Secondary electron microscopical imaging of multilayer coatings clearly showed that the various layers do not mix or interdiffuse, but maintain the same chemical composition and refractive indices as in single layers deposition. When the inorganic layer was deposited over the organic layer a graded interphase (around 40 nm thick) was detected, due to plasma ion bombardment of the underlayer.
The advantage of coupling iCVD and PECVD consists in the possibility of having dense inorganic coatings alternated with organic interlayers characterized by high crosslinking and high C content. Moreover the high smoothness of the iCVD layer is important to reduce the roughness of the under-layers in order to limit the formation of defects in the successive inorganic up-layer. Hence, all this properties make this kind of multilayer coatings promising as ultrahigh barriers (UHB) against the transmission of water vapor and oxygen through polymer substrates.