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High-rate sputtering of thick PZT thin films for MEMS

: Jacobsen, H.; Prume, K.; Wagner, B.; Ortner, K.; Jung, T.


Journal of electroceramics 25 (2010), Nr.2-4, S.198-202
ISSN: 1385-3449
ISSN: 1573-8663
Fraunhofer ISIT ()
Fraunhofer IST ()

Crack and void free polycrystalline Lead Zirconate Titanate (PZT) thin films in the range of 5 A mu m to 10 A mu m have been successfully deposited on silicon substrates using a novel high rate sputtering process. The sputtered PZT layers show a high dielectric constant epsilon(r) between 1,000 and 1,800 with a moderate dissipation factor tan (delta) = 0,002 -aEuro parts per thousand 0,01 measured at f = 1 kHz, a distinct ferroelectric hysteresis loop with a remanent polarisation of 17 A mu C/cm(2) and coercive field strength of 5.4 kV/mm. The piezoelectric coefficients d(33,f) = 80 pm/V are measured by using a Double Beam Laser Interferometer (DBLI). Based on this deposition process a membrane actuator mainly consisting of a SOI layer and a sputtered PZT thin film was prepared. The deflection of this membrane actuator depending on the driving voltage was measured with a white light interferometer and compared to the results of finite element analysis (FEA). With this approach a transverse piezoelectric coefficient of about e(31) = -11.2 C/m(2) was calculated, whereas all the other material parameters in the model were lent from PZT-5A.