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2012
Conference Paper
Title
Investigations on adhesion of sputtered layers on polytetrafluorethylene surfaces
Abstract
Because of its low refractive index, its low absorption and its very high crack onset strain polytetrafluorethylene (PTFE) is a promising material for the use in flexible optical layer systems. PTFE films can be easily deposited by RF magnetron sputter deposition from a PTFE target in argon atmosphere. PTFE is known for its very low surface energy, which yields high water contact angles. However due to the low surface energy, adhesion of layers on PTFE surfaces is generally poor. In this work we show results of recent investigations on the improvement of the adhesion of tantalum oxide (Ta2O5) layers on PTFE surfaces. Test layer stacks of Ta2O5 and PTFE were deposited on glass, silicon wafers and different polymer substrates. Between the PTFE and the Ta2O5 layer low-pressure plasma treatment of the PTFE layers was performed with different gases. The treated PTFE layers and Ta2O5-PTFE layers were characterized by spectral ellipsometry, infrared spectrometry, cross cutting tests and other methods to investigate the influence of the treatment time and atmosphere on the optical properties, the etching rate and the layer adhesion.