High Quality SiO2-like Layers by Large Area Atmospheric Pressure Plasma Enhanced CVD: Deposition Process Studies by Surface Analysis

This work reports on the main competing processes and their contribution to the properties of SiO2 layers on polymers in large area AP‐PE‐CVD from ArN2O2‐HMDSO mixtures. The detailed space resolved surface analysis on the statically deposited films showed smooth SiOx films in the vicinity of the gas injection, as deposited by HMDSO radicals. At the gas effluent, due to HMDSO depletion, non‐depositing species interact with the polymer and induce rough deposits with high carbon content. The competition of plasma–polymer surface interaction with HMDSO radicals deposition, is further confirmed from the analysis of films grown on polymers with a “protecting” layer and with reverse gas flow direction. Under web roll conditions, HMDSO radicals deposition is dominant, resulting in high quality SiOx layers along the whole electrode length. The understanding on the involved processes in AP‐PE‐CVD of SiO2, leading to high quality layers over large area polymeric substrate, is reported for the first time. The surface analysis performed on films deposited under different substrate configurations and at various gas flow directionalities, unravelled the different stages of growth involved in the deposition of uniform and smooth layers, as being controlled by the HMDSO radical deposition and polymer etching.