Skip to Main content Skip to Navigation

Maitrise de la microstructure de films minces d'or par traitements de surface pour l'optimisation du contact mécanique et ohmique des micro-relais mems.

Abstract : Ohmic MEMS switches made by gold thin films are promising devices but their mechanical contacts are one of the critical concerns for enhancing reliability. For this reason, surface processes are investigated in this work to improve both mechanical and electrical contact resistance (ECR) of MEMS gold contacts. Ruthenium ultra-thin films (20 to 100 nm) deposited on a top of gold layer increase surface hardness by a factor of fifteen. In parallel, surface implantations of both boron (<10% atomic) or nitrogen (<0.1% atomic) into gold reveals a solid solution hardening by insertion, thus increasing the hardness of initial film by about 75% and 25%, respectively. Notably, above 0.1% atomic of nitrogen, atoms precipitate from the tetra or octahedral sites of gold inducing a decrease of hardness.Static and multi load/unload spherical nano-indentation are performed on treated gold thin films to simulate the mechanical actuation of ohmic MEMS switches. Analysis of residual imprints (about few µm²) from treated surface exhibits both minimal local deformation and adhesion forces that reduce stiction probability. In-situ measurement of ECR for treated gold by instrumented nano-indentation, reproducing the design of MEMS, is in the same range of pure gold-to-gold configuration.A new mechanical discrete model of rough contact is introduced, confronted and validated to the experimental mechanical surface deformation obtained by comparison of AFM images before and after spherical nano-indentation. An electrical discrete model is added and fitted to the ECR measurements. In ohmic MEMS switch load range (< 1 mN), the conductive area is found to be about 2% to 9% of the real contact area.
Document type :
Theses
Complete list of metadatas

Cited literature [50 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-01089963
Contributor : Abes Star :  Contact
Submitted on : Tuesday, December 2, 2014 - 4:20:55 PM
Last modification on : Friday, March 6, 2020 - 1:19:43 AM
Document(s) archivé(s) le : Tuesday, March 3, 2015 - 1:16:38 PM

File

brice-Arrazat-diff.pdf
Version validated by the jury (STAR)

Identifiers

  • HAL Id : tel-01089963, version 1

Collections

Citation

Brice Arrazat. Maitrise de la microstructure de films minces d'or par traitements de surface pour l'optimisation du contact mécanique et ohmique des micro-relais mems.. Autre. Ecole Nationale Supérieure des Mines de Saint-Etienne, 2012. Français. ⟨NNT : 2012EMSE0644⟩. ⟨tel-01089963⟩

Share

Metrics

Record views

387

Files downloads

370