Inhibition of Interfacial Oxidative Degradation During SiO_xPlasma Polymer Barrier Film Deposition on Model Organic Substrates

Abstract

Interfacial processes during the initial stages of SiO x -like plasma-polymer barrier coating deposition were investigated by means of polarization modulation infrared reflectionabsorption spectroscopy, and the resulting effect on defect densities were studied by cyclic voltammetry. Octadecanethiol self-assembled monolayers on Au-film coated wafers served as sensor layers to investigate interface chemistry during the plasma deposition. Both the spectroscopic and electrochemical data revealed that a thin SiOCH interlayer could reduce oxidative degradation of the SAM during subsequent deposition of the SiO x barrier film from an oxygen-rich plasma phase. The present electrochemical investigation confirmed effective inhibition of interfacial oxidative degradation processes of an aliphatic polymer in the presence of a SiOCH interfacial layer.

Spectroscopic and Microscopic Investigations of Degradation Processes in Polymer Surface‐Near Regions During the Deposition of SiOx Films

“…For coatings deposited on ODT with oxygen to HMDSO ratios between 0 and 4 the peak position of CH 2 asymmetric stretching stayed identical. This indicates that the all‐trans conformation of the alkyl chains of ODT did not change by exposure to a plasma with an oxygen to HMDSO ratio of 4 and a corresponding atomic oxygen fluence of 6.0 · 10 21 m −2 . Thus, the ODT‐SAM stayed intact and an interlayer deposited with an oxygen to HMDSO ratio of 4 is capable of protecting the interface.…”

“…In order to obtain a fundamental understanding of the interfacial processes during the initial stages of barrier coating deposition on polyolefins, crystalline aliphatic self‐assembled monolayers (SAMs) of octadecanethiol (ODT) were deposited onto gold substrates and used as a sensor layer that mimics an aliphatic polymer . The SAMs had a thickness of approximately 2 nm.…”

“…In addition to that, the morphology of applied coatings was investigated by means of atomic force microscopy (AFM). In a previous work, it was shown that a high atomic oxygen flux of 2 · 10 23 m −2 s −1 led to oxidative degradation of the ODT‐SAM, whereas no admixture of oxygen led to the formation of an interlayer that protected the ODT‐SAM from oxidative degradation …”

A combinatorial approach to enhance barrier properties of thin films on polymers: Seeding and capping of PECVD thin films by PEALD

“…While sputtering employs high‐cost setups and is accompanied by challenges in terms of its line‐of‐sight deposition as well as difficulties with respect to the polymer substrates, thin films from PECVD are easier to produce and growth rates in PECVD are on the order of 3 × 10 1 –4 × 10 2 nm min −1 , enabling fast depositions and high throughputs. It was also deduced via PECVD that the introduction of a thin, less oxidized interlayer (SiO x C y H z ), deposited from hexamethyldisiloxane (HMDSO), can significantly increase the GBL performance of a subsequently grown SiO x layer from the same precursor . During the initial steps of deposition, the surface chemistry of the polymer is also influenced .…”

“…Furthermore, the chemical structure of the deposited inorganic thin films and hence barrier performance can change . Interactions with oxygen in particular, are known to trigger degradative processes at the interface which influences the formation and cross‐linking of the barrier film . For example, the interface of a polymer and a growing thin film is known to be comprised of a mixture of coating species and etched polymer products .…”