Postbuckled micromachined square membranes under differential pressure

Abstract

We report quantitative results on the load-deflection response of compressively prestressed square membranes under differential pressure. The membranes consist of 1.9 μm thick silicon nitride films with a compressive prestrain ε0 = −(1.6 ± 0.1) × 10−3. For these square membranes we observed a new symmetry transition of the deflection profile from a state without reflection symmetries at small loads to a state with reflection symmetries at sufficiently large loads. The load-deflection response was modeled by finite element simulations covering a wide range of prestrains ε0 and pressures using various geometries. From the symmetry transition process, Young's modulus E = (150 ± 7) GPa of the membrane material was extracted.