Analysis of the surface effects on adhesion in MEMS structures

•The adhesion force decreases with the increase of roughness.•The adhesion force increases with the increase of the asperity radius.•The adhesion force is influenced by surface energy, roughness, radius of the AFM tip.•The theoretical values of the adhesion force are in accord with the experimental...

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Bibliographic Details
Published in:Applied surface science 2015-12, Vol.358, p.634-640
Main Authors: Rusu, F., Pustan, M., Bîrleanu, C., Müller, R., Voicu, R., Baracu, A.
Format: Article
Language:English
Subjects:
Adhesion
Adhesive strength
Aluminum
Contact
Failure modes
MEMS materials
Roughness
Silicon
Stiction
Tribological characterization
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Summary:•The adhesion force decreases with the increase of roughness.•The adhesion force increases with the increase of the asperity radius.•The adhesion force is influenced by surface energy, roughness, radius of the AFM tip.•The theoretical values of the adhesion force are in accord with the experimental ones.•The adhesion force decreases with the temperature increase for Pt, Au, Si, and polysilicon samples. One of the main failure causes in microelectromechanical systems (MEMS) is stiction. Stiction is the adhesion of contacting surfaces due to surface forces. Adhesion force depends on the operating conditions and is influenced by the contact area. In this study, the adhesion force between MEMS materials and the AFM tips is analyzed using the spectroscopy in point mode of the AFM. The aim is to predict the stiction failure mode in MEMS. The investigated MEMS materials are silicon, polysilicon, platinum, aluminum, and gold. Three types of investigations were conducted. The first one aimed to determine the variation of the adhesion force with respect to the variation of the roughness. The roughness has a strong influence on the adhesion because the contact area between components increases if the roughness decreases. The second type of investigation aimed to determine the adhesion force in multiple points of each considered sample. The values obtained experimentally for the adhesion force were also validated using the JKR and DMT models. The third type of investigation was conducted with the purpose of determining the influence of the temperature on the adhesion force.
ISSN:0169-4332
1873-5584
DOI:10.1016/j.apsusc.2015.09.052