Transparent Thin Films Deposited onto Polyester Film Substrate by Radio Frequency Sputtering with a Poly(tetrafluoroethylene) Target

Abstract

Improvement technologies for antireflection property of transparent plastic substrates are required in computer displays. Inorganic coatings have been used to reduce the surface reflection. We have already reported that fluorocarbon thin films sputtered with a poly(tetrafluoroethylene) (PTFE) target are transparent and can be used for an antireflection film, although the pristine PTFE plate used for the sputtering target is white. The fluorocarbon thin films were deposited onto a polyester (PET) film substrate by an rf sputtering, and characterized their optical properties. Elemental ratio, fluorine for carbon, of the thin films increased and degree of cross-linking of the thin films decreased with an increase of the rf power. Arithmetical surface roughness of the fluorocarbon thin films slightly increased with an increase of the rf power. Surface roughness of the fluorocarbon thin film affects the transmittance as well as the chemical structure of the thin film. To enhance the transparency, the diffuse transmittance should be suppressed, and flat surface thin films should be prepared by the sputtering at lower rf power and pressure.

Fluorocarbon Thin Films Fabricated using Carbon Nanotube/Polytetrafluoroethylene Composite Polymer Targets via Mid-Frequency Sputtering

“…Biederman et al . proposed a molecular structural model of the fluorocarbon thin film prepared by RF sputtering, which suggests that the fluorocarbon thin film contains cross-linking structures that would enhance the formation of an amorphous structure 6 , 38 .…”

“…Among the various polymer targets, a polytetrafluoroethylene (PTFE) polymer target has been mostly used for depositing an organic thin film via a sputtering process 1 – 6 , 12 – 58 . Fluorocarbon thin films deposited via radio-frequency (RF) sputtering using PTFE targets have many advantageous surface properties, such as hydrophobicity and super-hydrophobicity 30 – 36 , icephobicity 32 , oleophobicity 36 , high optical transmittance 37 , 38 , dielectric 39 and mechanical properties 40 – 47 , as well as antimicrobial 48 characteristics. Thus, these thin films have recently garnered a substantial amount of attention in practical applications for flat panel displays, automobiles, fabrics 49 , membranes 50 , and high-frequency applications 51 .…”

“…The Faupel group focused on nanocomposite thin films formed by the methods of metal-polymer co-sputtering and multilayer processes 40 , 45 , 47 , 51 , 52 . The Iwamori group reported many research outcomes focusing on the optical and mechanical properties of RF-sputtered fluorocarbon thin films 22 , 24 , 33 , 34 , 38 , 41 , 42 .…”

Effects of copper interfacial layer on surface characteristics, adhesion and wear durability of fluorocarbon thin film sputtered onto polyimide film substrate

“…The elemental compositions (fluorine for carbon content, F/C ratio) of these fluorocarbon thin films were already reported, and the F/C ratios slightly increased with increase of the r.f. power [21]. The fluorine content affects the hydrophobicity and the higher fluorine content polymers indicate the higher hydrophobicity.…”

“…In this experiment, the hydrophobicity of fluorocarbon thin film prepared at 75 W was slightly higher than that prepared at 35 W. We had also reported that the surface roughness (Ra) of fluorocarbon thin film increased with increase of r.f. power at the sputtering [21]. It is considered that the surface morphology of the thin film may strongly affect the hydrophobicity in this experiment.…”