Controlling the transmission of ultrahigh frequency bulk acoustic waves in silicon by 45° mirrors

S. Wang , J. Gao , Julien Carlier (1, 2) , Pierre Campistron , Assane Ndieguene , S. Guo , Olivier Bou Matar , Dorothée Debavelaere-Callens , Bertrand Nongaillard (1)

1 IEMN - Institut d’Électronique, de Microélectronique et de Nanotechnologie - UMR 8520
2 MAMINA - IEMN - Matériaux et Acoustiques pour MIcro et NAno systèmes intégrés - IEMN

In this paper, we present a feasible microsystem in which the direction of localized ultrahigh frequency (∼1 GHz) bulk acoustic wave can be controlled in a silicon wafer. Deep etching technology on the silicon wafer makes it possible to achieve high aspect ratio etching patterns which can be used to control bulk acoustic wave to transmit in the directions parallel to the surface of the silicon wafer. Passive 45° mirror planes obtained by wet chemical etching were employed to reflect the bulk acoustic wave. Zinc oxide (ZnO) thin film transducers were deposited by radio frequency sputtering with a thickness of about 1 μm on the other side of the wafer, which act as emitter/receptor after aligned with the mirrors. Two opponent vertical mirrors were inserted between the 45° mirrors to guide the transmission of the acoustic waves. The propagation of the bulk acoustic wave was studied with simulations and the characterization of S21 scattering parameters, indicating that the mirrors were efficient to guide bulk acoustic waves in the silicon wafer.

Mots clés: 45° Mirror; Bulk acoustic wave; Propagation controlling; Ultrahigh frequency

Domaines: Sciences de l'ingénieur [physics]

S. Wang, J. Gao, Julien Carlier, Pierre Campistron, Assane Ndieguene, et al.. Controlling the transmission of ultrahigh frequency bulk acoustic waves in silicon by 45° mirrors. Ultrasonics, 2011, 51, pp.532-538. ⟨10.1016/j.ultras.2011.01.003⟩. ⟨hal-00574498⟩