Gentle dry etching of P(VDF-TrFE) multilayer micro actuator structures by use of an inductive coupled plasma

To fully utilize the actuator properties of poly(vinylidenefluoride) (P(VDF))-based polymers, the electric field has to be rather high and one way to accomplish this, in particular with low voltage drive signals, is to build multilayered structures. This paper focuses on how to structure poly(vinylidenefluoride-trifluoroethylene) P(VDF-TrFE) by presenting an etch method to create multilayered miniaturized actuators, with intermediate aluminium electrodes. To create inter-connect areas for the multilayer electrodes, a modified Bosch process in an inductive couple plasma (ICP) etcher is used to remove all P(VDF-TrFE) not covered by the electrodes. Since each electrode mask is slightly different from the others, the result is a staircase-like inter-electrode contact area that is connected from above using a conductive adhesive. The developed ICP etch results in high selective etching and a good agreement between theoretical and measured capacitance values. The manufactured cantilevers, consisting of a multilayer on top of a flexible printed circuit (FPC) board, were tested and the resonant stroke was confirmed to agree with expected values. The successful establishment of interlayer connections between the electrodes open up the possibility for batch fabrication of cheap low voltage micro actuators built on a standard substrate used in millions of commercial products.

[1]  M. Manohara,et al.  Transfer by direct photo etching of poly(vinylidene flouride) using X-rays , 1999 .

[2]  Stefan Bauer,et al.  Plasma-deposited fluorocarbon coatings for passive and active integrated optical devices , 1994, Integrated Optoelectronics.

[3]  N. Betz,et al.  Swift heavy ion induced graft polymerization in track etched membranes’ submicroscopic pores , 2004 .

[4]  N. Neumann,et al.  Pyroelectric single-element and linear-array sensors based on P(VDF/TrFE) thin films , 1994 .

[5]  E. Fukada.  History and recent progress in piezoelectric polymers , 2000, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[6]  F. Bauer,et al.  PVDF shock sensors: applications to polar materials and high explosives , 2000, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[7]  M. Grasselli,et al.  Making porous membranes by chemical etching of heavy-ion tracks in β-PVDF films , 2005 .

[8]  P. Slade,et al.  Electrical breakdown in atmospheric air between closely spaced (0.2 /spl mu/m-40 /spl mu/m) electrical contacts , 2001 .

[9]  T. Nevell,et al.  The effects of etching on the surface of plasticized poly(vinylidene fluoride) , 1998 .

[10]  Javad Dargahi,et al.  Design and microfabrication of a hybrid piezoelectric‐capacitive tactile sensor , 2006 .

[11]  P. Regtien,et al.  Application of VDF/TrFE copolymer for pyroelectric image sensors , 1994 .

[12]  Mori Norio,et al.  Polyvinylidene fluoride microfilter formation by 35Cl9+, 58Ni10+, and 63Cu11+ ion bombardment and alkali etching , 1988 .

[13]  M. Schmidt,et al.  Characterization of a Time Multiplexed Inductively Coupled Plasma Etcher , 1999 .

[14]  R. Dhariwal,et al.  Electric field breakdown at micrometre separations , 1999 .

[15]  Y. Schneider,et al.  Characterisation of energetic heavy ion track in PVDF: Production of PVDF track-etched membrane and application , 1995 .

[16]  Brian J. Simonds,et al.  Submicron gap capacitor for measurement of breakdown voltage in air , 2006 .

[17]  Bruce Isler,et al.  Spatial aperture shading of polyvinylidene fluoride applied to distributed systems for uniform damping control , 2003 .