Surface micromachined BAW resonators based on AlN

Author

Lanz, Roman ; Carazzetti, Patrick ; Muralt, Paul

Author_Institution

Ceramics Lab., Ecole Polytech. Fed. de Lausanne, Switzerland

Volume

1

fYear

2002

fDate

8-11 Oct. 2002

Firstpage

981

Abstract

This contribution deals with surface micromachined BAW resonators based on AlN thin films. Process, design issues and first results are presented and discussed. Devices with two resonators in series having a resonance frequency between 7 and 8 GHz show promising results. Coupling coefficients of k_t² =3.8% and quality factors of 100 to 150 have been obtained with resonators having a approximate size of 30×30μm adapted for a 50Ω system. These results are clearly inferior to earlier results obtained with SMR designs (k_t²=5.5% and Q=580). Reasons are too high serial resistances caused by bad step coverage of the top electrode, possibly also incomplete etching of the sacrificial layer, and warping by too large film stresses.

Keywords

III-V semiconductors; aluminium compounds; micromachining; piezoelectric semiconductors; piezoelectric thin films; semiconductor thin films; surface acoustic wave resonator filters; wide band gap semiconductors; 30 micron; 50 ohm; 7 to 8 GHz; AlN; AlN film; bad step coverage; coupling coefficients; design issues; high serial resistances; incomplete etching; large film stresses; process issues; resonance frequency; sacrificial layer; surface micromachined BAW resonators; warping; Band pass filters; Dry etching; Electrodes; Fabrication; Film bulk acoustic resonators; Piezoelectric films; Resonator filters; Silicon compounds; Sputtering; Substrates;

fLanguage

English

Publisher

ieee

Conference_Titel

Ultrasonics Symposium, 2002. Proceedings. 2002 IEEE

ISSN

1051-0117

Print_ISBN

0-7803-7582-3

Type

conf

DOI

10.1109/ULTSYM.2002.1193560

Filename

1193560