The design, fabrication, and testing of corrugated silicon nitride diaphragms

Abstract

Silicon nitride corrugated diaphragms of 2 mm x 2 mm x l p m have been fabricated with 8 circular corrugations, having depths of 4 1 0 , or 14 pm. The diaphragms with 4-pm-deep corrugations show a measured mechanical sensitivity (increase in the deflection over the increase in the applied pressure) which is 25 times larger than the mechanical sensitivity of flat diaphragms of equal size and thickness. Since this gain in sensitivity is due to reduction of the initial stress, the sensitivity can only increase in the case of diaphragms with initial stress. A simple analytical model has been proposed that takes the influence of initial tensile stress into account. The model predicts that the presence of corrugations increases the sensitivity of the diaphragms, because the initial diaphragm stress is reduced. The model also predicts that for corrugations with a larger depth the sensitivity decreases, because the bending stiffness of the corrugations then becomes dominant. These predictions have been confirmed by experiments. The application of corrugated diaphragms offers the possibility to control the sensitivity of thin diaphragms by geometrical parameters, thus eliminating the effect of variations in the initial stress, due to variations in the diaphragm deposition process andlor the influence of temperature changes and packaging stress.

The Development of a Biologically-Inspired Directional Microphone for Hearing Aids

“…Myriad approaches have been developed to reduce the effects of stress on silicon microphones including the use of corrugations and stress relieving supports [see for example Scheeper et al, 1994;Bergqvist and Rudolf, 1994;Zhang and Wise, 1994;Jennan, 1990;Cunningham and Bernstein, 1997;Spiering et al, 1993].…”

Incremental deformation analysis of shell and corrugated diaphragm based on arbitrary configuration

“…In recent years, more and more flat and corrugated diaphragms have been used in sensors and actuators of MEMS, such as single-chip condenser microphones [1,2], microvalves [3] and micropumps [4]. These elastic elements play important roles to transfer the external loads such as pressures into the deformation of the microfabricated structures, so as to identify the associated electromechanical, chemical and even biological reactions, or to drive the related elements to actions.…”

A corrugated bridge of low residual stress for RF-MEMS switch

“…Analytical analysis studies of membranes with corrugations have been so far reported in literatures of microphones [15][16][17][18]. As mentioned here, an expression for the residual stress of corrugated membranes with intrinsic residual stress is deduced from an algebraic description of geometrical modeling.…”