New results of micromachined silicon subminiature microphones using piezoelectric polymer layers

Author

Kressmann, Reiner ; Hess, Gisela ; Schellin, Ralf

Author_Institution

Inst. for Telecomm. & Electroacoust., Tech. Univ. of Darmstadt, Germany

fYear

1996

fDate

25-30 Sep 1996

Firstpage

1044

Lastpage

1049

Abstract

A micromachined silicon subminiature microphone based on piezoelectric P(VDF-TrFE) films spin-coated on top of silicon nitride membranes is presented. The residual tensile in-plane-stress is minimized by an additional boron implantation as well as by using a stress compensated layer system of silicon dioxide and silicon nitride. Spin-coating and corona poling of 70/30-P(VDF-TrFE) is described as well as important properties of these layers. The acoustic measurements were done on-wafer and yielded a sensitivity of 0.21 mV/Pa and therefore an equivalent noise level of 54.6 dB(A). The bandwidth is about 17 kHz, and the total harmonic distortion is less than 1.8% even for 127.5 dBSPL

Keywords

dielectric polarisation; harmonic distortion; internal stresses; ion implantation; micromachining; microphones; microsensors; piezoelectric thin films; piezoelectric transducers; polymer blends; polymer films; semiconductor device noise; 17 kHz; B implantation; Si; Si₃N₄ membranes; Si₃N₄-SiO₂-Si; acoustic measurements; corona poling; equivalent noise level; micromachined Si subminiature microphones; piezoelectric P(VDF-TrFE) films; piezoelectric polymer layers; residual tensile in-plane-stress minimization; sensitivity; spin-coating; stress compensated layer system; total harmonic distortion; Acoustic measurements; Biomembranes; Boron; Corona; Microphones; Piezoelectric films; Residual stresses; Semiconductor films; Silicon compounds; Tensile stress;

fLanguage

English

Publisher

ieee

Conference_Titel

Electrets, 1996. (ISE 9), 9th International Symposium on

Conference_Location

Shanghai

Print_ISBN

0-7803-2695-4

Type

conf

DOI

10.1109/ISE.1996.578256

Filename

578256