Bulk acoustic wave transformer based on the combination of the high-ε epitaxial PbTiO3 and low-ε ScAlN thin films

Single crystalline lithium niobate (LN) thin films with a Y43-cut are fabricated by crystal-ion-slicing technique, and the B-staged benzocyclobutene (BCB) polymer is used as the bonding medium for the transferring of the LN thin film on to a homogeneous LN substrate. The thickness of the LN film is about 910 nm, and low energy ion irradiation is used to treat the surface of the film, which reduces the roughness from 12.4 nm down to 3.6 nm. Bulk acoustic wave (BAW) resonator is fabricated based on the thin LN layer, and the electromechanical coefficient (k2t) of the LN film reaches 16.3%. A 3-stage BAW filter is obtained, and the 3 dB bandwidth of the filter is 8.5%, demonstrating the single crystalline LN thin film with large k2t is promising for wide band filter.

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Development of 4 GHz bulk acoustic wave resonators by sputtered Pb(Mn,Nb)O3-Pb(Zr,Ti)O3 thin films

2008 IEEE Ultrasonics Symposium ◽

10.1109/ultsym.2008.0473 ◽

2008 ◽

Cited By ~ 1

Author(s):

N. Yamauchi ◽

T. Shirai ◽

T. Yoshihara ◽

Y. Hayasaki ◽

T. Matsushima ◽

...

Keyword(s):

Thin Films ◽

Acoustic Wave ◽

Bulk Acoustic Wave ◽

Acoustic Wave Resonators ◽

Bulk Acoustic Wave Resonators

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Characterisation of PZT in Thin Film Bulk Acoustic Wave Resonators

MRS Proceedings ◽

10.1557/proc-1075-j03-03 ◽

2008 ◽

Vol 1075 ◽

Author(s):

Janine Conde ◽

Paul Muralt

Keyword(s):

Thin Films ◽

Acoustic Wave ◽

Bias Voltage ◽

Sol Gel ◽

Low Frequency ◽

Bulk Acoustic Wave ◽

Coupling Constant ◽

Pzt Thin Films ◽

Best Response ◽

And Performance

ABSTRACTPb(Zr0.53, Ti0.47)O3 (PZT) thin films are potentially interesting as piezoelectric layer in bulk acoustic wave (BAW) resonators. We investigated properties and performance of {111} and {100} textured, dense films deposited by sol-gel techniques in the frequency range of 1 to 2 GHz. The resonators were fabricated on Si wafers using deep silicon etching to create a membrane structure and using platinum as top and bottom electrodes. The best response of the resonators was observed at a bias voltage of −15kV/cm with values of around 10% for the coupling constant and around 50 for the quality factor. This voltage corresponds to the maximal value of the piezoelectric constant d33 and minimal value of the dielectric permittivity measured as a function of the electric field. Resonance and antiresonance frequencies were strongly influenced by a bias voltage, showing a hysteretic behaviour as expected for ferroelectrics. Both of these frequencies shifted in the same direction. As a consequence, the dc voltage can be potentially used to shift the whole band of a filter. In unipolar operation, the coupling constant could be varied from 6 to 10 %. Materials parameters were extracted from the admittance as a function of frequency. Dielectric, piezoelectric and elastic properties of textured PZT films are reported and compared to direct (low frequency) measurements and to literature values. It was found that PZT thin films have lower stiffness than the one of PZT bulk ceramics and it was observed that {111}-textured films are stiffer than {100}-textured films.

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Stress Adjustment and Characteristics Improvement in a 1.8GHz Range Film Bulk Acoustic Wave Resonator by Using Multi-layer Structure of ZnO/A12O3/SiO2

MRS Proceedings ◽

10.1557/proc-741-j5.9 ◽

2002 ◽

Vol 741 ◽

Author(s):

Masaki Takeuchi ◽

Hajime Yamada ◽

Hideki Kawamura ◽

Yoshihiko Goto ◽

Tadashi Nomura ◽

...

Keyword(s):

Thin Films ◽

Acoustic Wave ◽

Temperature Coefficient ◽

Layer Structure ◽

Fem Simulation ◽

Bulk Acoustic Wave ◽

Positive Temperature ◽

Bulk Acoustic Wave Resonator ◽

Wave Resonator ◽

Film Bulk

ABSTRACTStress adjustment and improvement of electrical characteristics in film bulk acoustic wave resonator (BAW) have been successfully carried out in 1.8GHz range by using a multi-layer structure of ZnO / Al2O3 / SiO2. The BAW resonator, designed on secondary harmonics at about 1.8GHz, has Al / ZnO / Al / Al2O3 / SiO2 structure. ZnO and SiO2 thin films have a negative and a positive temperature coefficient of sound velocity, respectively. So temperature coefficient of frequency (TCF) of the BAW resonator can be controlled by the thickness ratio of ZnO and SiO2 thin films. Since both ZnO and SiO2 have compressive stress, and Al2O3 has tensile one, the stress of the membrane is reduced by combining these thin films so that the membrane can avoid deformation. The BAW resonator, with thickness of ZnO / Al2O3 / SiO2=1.2 /0.45/1.25 microns, was designed by finite element method (FEM) simulation and fabricated. The value of quality factor (Q factor) and the TCF of the BAW resonator were realized over 1000 and −20 ppm/degree C, respectively. The Q of ZnO / Al2O3 / SiO2 structure was higher than that of ZnO / SiO2 one with keeping small TCF.

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