Reactive ion etching of poly(vinylidene fluoride-trifluoroethylene) copolymer for flexible piezoelectric devices

A microfabrication process for poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) based flexible piezoelectric devices is proposed using heat controlled spin coating and reactive ion etching (RIE) techniques. Dry etching of P(VDF-TrFE) in CF₄+O₂ plasma is found to be more effective than that using SF₆+O₂ or Ar+O₂ feed gas with the same radiofrequency power and pressure conditions. A maximum etching rate of 400 nm/min is obtained using the CF₄+O₂ plasma with an oxygen concentration of 60% at an antenna power of 200 W and a platen power of 20 W. The oxygen atoms and fluorine atoms are found to be responsible for the chemical etching process. Microstructuring of P(VDF-TrFE) with a feature size of 10 μm is achieved and the patterned films show a high remanent polarization of 63.6 mC/m².