PECVD and PEALD on polymer substrates (part I): Fundamentals and analysis of plasma activation and thin film growth

Abstract

This feature article presents recent results on the analysis of plasma/polymer interactions and the nucleation of ultra‐thin plasma films on polymeric substrates. Because of their high importance for the understanding of such processes, in situ analytical approaches of the plasma volume as well as the plasma/substrate interfaces are introduced before the findings on plasma surface chemistry. The plasma activation of polymeric substrates is divided into the understanding of fundamental processes on model substrates and the relevance of polymer surface complexity. Concerning thin film nucleation and growth, both plasma‐enhanced chemical vapor deposition and plasma‐enhanced atomic layer deposition processes as well as the combination of both processes are considered both for model substrates and technical polymers. Based on the comprehensive presentation of recent results, selective perspectives of this research field are discussed.

On the role of defects in modelling approaches for thin film gas barrier coatings on polymer substrates: I. Model development

“…For each segment ij that represents a defect, the diffusion coefficient of the defect D ij can be calculated with equation (4), where the diameter of the defect d d = x j − x i to get an expression for c i − c j . Conversely, D ij = D bulk for each segment representing bulk material, resulting in…”

“…Adjusting the permeability of plastics is an important task in many applications such as food or pharma packaging, membrane technology or water-sensitive OLED displays, and thus the subject of ongoing research activities [1][2][3]. Besides many other approaches, the plasma-enhanced deposition of thin film coatings stands out due to its versatility, low material usage and long-term stability [4]. In the course of this work, we expand on silicon-oxide (SiO x ) coatings deposited via the * Author to whom any correspondence should be addressed.…”

PECVD and PEALD on polymer substrates (part II): Understanding and tuning of barrier and membrane properties of thin films

“…Figure 15 shows measured average ion energy and number of incident atomic oxygen atoms per deposited Si atom when varying the position of the substrate bias, relative areas of Si2p components (as determined by XPS) in the obtained coatings as well as the resulting oxygen transmission rate (OTR) for estimation of barrier performance. The pulsed substrate bias was positioned either in the MW discharge (positions [1]- [5]) or during the MW pause (positions [6]- [10]) while varying the length of the bias. Applying a substrate bias during the MW discharge leads to an increase in the average ion energy per Si atom deposited from 33 to 160 eV while keeping the number of atomic oxygen atoms per Si atom deposited at about 4300.…”

“…The reader is referred to part I of our feature article for a more detailed description and comparison of both methods. [1] This paper represents part of the research developed within the frame of the transregional project SFB-TR 87 ("Pulsed high power plasmas for the synthesis of nanostructured functional layers"), which aims to understand mass transfer processes through coated plastics and membranes. To this end, experimental methods are contrasted with simulative methods and discussed.…”