MEMS Electrode Stress Deformation

Johannes Hiesberger Electrical Engineering;MEMS;NEMS

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Hello everyone,

I am trying to simulate a MEMS beam model with gold electrodes on top. These electrodes are made from gold and are supposed to be used to read-out the deformation of the beam resonator through the piezoresistive effect. For this reason, I am interested in the strain of the gold and start with "Solid Mechanics" and a "Stationary" study. Since the beam structure has an intrinsic stress, this is something I considered in the model, but once I actually compute the "Stationary" study I get a lot of deformation, which is apparently due to the stress. In the end what I would like to do is put different external forces on the resonator and look at the change in strain or directly in resistance of the gold.

Does anyone have experience with using two layers of material with similar thicknesses on top of one another?

I included a picture of the deformation and the example project I described.

Thank you very much in advance for any help you can provide. Johannes



1 Reply Last Post Sep 27, 2022, 3:03 p.m. EDT
Henrik Sönnerlind COMSOL Employee

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Posted: 2 months ago Sep 27, 2022, 3:03 p.m. EDT

As I understand it, you want the stresses only added to the stress tensor, but not giving displacements. That is, you do not want to enforce equilibrium (no force balance).

If it is so, you can use an External Stress node with the option Residual Stress.

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Henrik Sönnerlind
COMSOL
As I understand it, you want the stresses only added to the stress tensor, but not giving displacements. That is, you do not want to enforce equilibrium (no force balance). If it is so, you can use an *External Stress* node with the option *Residual Stress*.

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