Fabrication of micromachined piezoelectric diaphragm pumps actuated by interdigitated transducer electrodes

Eunki Hong, S. V. Krishnaswamy, T. T. Braggins, C. B. Freidhoff, Susan E. Trolier-McKinstry

Research output: Contribution to journalConference article

1 Scopus citations

Abstract

Micromachined pump structures were fabricated using surface micromachining. The structures consisted of three or five connected chambers. Sequential actuation of the diaphragms on these chambers will yield peristaltic pumping. As the actuation material, lead zirconate titanate (PZT [53/47]) thin films were employed and actuated by interdigitated transducer (IDT) electrodes. First, chambers and channels on the 4″ (100) silicon wafers were defined by reactive ion etching (RIE) and thermally oxidized. The etched structures were then filled with amorphous silicon. Low temperature (silicon) oxide (LTO) and PZT films were then deposited. The LTO and PZT layers act as passive and active layers in a piezoelectric unimorph, respectively. A ZrO2 layer was employed to prevent reaction between SiO2 and PZT layers. A Cr/Au electrode was evaporated on top of the PZT layer and patterned into ring-shaped IDT electrodes. Finally, a porthole at each end of the pump structures was defined by ion milling and the whole micropump structure was released by removing the sacrificial amorphous silicon using XeF2. Completely released 500 μm diameter pump structures were fabricated. The remanent polarizations of the PZT films on released diaphragms were ∼20 μC/cm2 and their coercive fields were ∼50 kV/cm. 500 μm diameter diaphragms were deflected as much as 2 μm with 120 V applied. The shape and behavior of the diaphragm deflection can be explained by considering both d31 and d33 piezoelectric coefficients of the PZT films.

Original languageEnglish (US)
Pages (from-to)111-116
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Volume741
StatePublished - Dec 1 2002
EventNano- and Microelectromechanical Systems (NEMS and MEMS) and Molecular Machines - Boston, MA, United States
Duration: Dec 2 2002Dec 4 2002

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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