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buckling of a fixed mems membrane with initial stress applied

Posted Oct 28, 2013, 6:44 a.m. EDT MEMS & Nanotechnology, MEMS & Piezoelectric Devices, Structural Mechanics Version 4.1 0 Replies

Szymon Sowizral
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Hello, I am a new Comsol user and I have a problem with a simulation of a multilayer vcsel mems membrane. The simulated data is different form the meassured one. The geometry of my structure is a four-leg membrane with a round plate in the center (plate diameter=120um, leg width=60um, leg length=140um)

example: ej.iop.org/images/0268-1242/28/1/012001/Full/sst446281f1_online.jpg

The membrane has 23 layers (Si3N4 and SiO2 alternately) of ca. 200nm thickness each. The legs are fixed at their ends (side surfaces). Each layer is prestressed (SiO2: -100MPa, Si3N4(bottom layers): 50MPa, Si3N4(upper layers): -160MPa). This Initial Stress makes the membrane buckle upwards. The experimental result is a deformation of 4.5 um (in the center of the memrane) . The simulation result is 1um.

I am using mems module, 3d geometry, application is solid mechanics, linear elastics material model, including geometric nonlinearity (large dimensions: on) and use nonlinear solver.

I would be very thankful for any hints.
0 Replies Last Post Oct 28, 2013, 6:44 a.m. EDT
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Hello Szymon Sowizral

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