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Mécanique des matériaux et nanostructures  
Nanomechanics
Materials Mechanics
Nanostructuring via charged particle beams
Nanostructuring via electrodeposition
Micropatterning of medical implant surfaces
Microanalysis
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Laboratory for Mechanics of Materials and Nanostructures
Research Activities
Materials Mechanics and Nanomechanics
Nanobending test to measure fracture strength of silicon nanowire
Macroscopically mechanical properties are dominated by a statistical distribution of defects with characteristic length scales like size and distribution of flaws in brittle fracture (100um), or dislocation interdistance in metal plasticity (100nm). As dimensions are scaled down below the characteristic length, material properties become controlled by geometrical constraints. This includes physical device dimensions as well as microstructure length scales like grain size. Whereas microstructure size effects are used for decades for hardening of metals, physical size effects have been studied only recently pushed by the ongoing miniaturization (MEMS, NEMS etc.). We study fundamental nanoscopic scale effects on mechanical properties related to device dimensions as well as to microstructure length scales. Applications range from new instrumentation for nanomechanical testing, thin film mechanics, mechanics of semiconductor processing like wafer dicing, to reliability of nuclear power plants.
Nanostructuring of metals
Three-dimensional structuring with focused electron beam induced deposition
Conventional optical lithographic techniques that form the basis of integrated-circuit chip fabrication can already be used to create sub-100 nm features, but requires huge investments. We explore new nanostructuring strategies for metals based on electrochemical and charged particle beam lithography techniques. On the one hand, electron and ion beam induced deposition is an attractive nanofabrication tool due to its capability of depositing structures of metallic material with nanoscale control of both size and placement. Potential applications range from functionalization of AFM tips (MFM, SNOM, tip enhanced Raman spectroscopy), sub-micron devices (Hall sensor, 4-point probes) to industrial scale photolithography mask repair tools. Our research concentrates on issues related to the minimum size attainable, the purity (composition, carbon contamination, crystallinity), and the properties of the deposits (density, mechanical, electrical). On the other hand, most electroformed components are nanocrystalline and are used as mechanical elements (e.g. gear, tools, etc). UV- and electron beam  lithography in combination with electrodeposition of nanocrystalline Nickel is today the only established technique to synthesize metallic MEMS and watch parts. Electrodeposition of metal nanowires has potential applications in interconnects for nanoelectronics or in acoustical sensor technology. Our research focuses NiCo alloys and ternary compounds of Fe-Ni-Cr (stainless steel) for applications in the watch and MEMS industry. Within technology transfer projects we exploit our knowledge also for micropatterning of medical implant surfaces.
Microanalysis
Depth profile of thin oxide film with 2nm thick Cr enriched layer in 20nm distance from the surface

Novel research in nanomechanics and nanostructuring requires specialised instrumentation, not all of which is available commercially. The microanalysis group within the Laboratory for Mechanics of Materials and Nanostructures has

  • glow discharge instruments which are used for (quantitative) chemical depth profiling with nanometer depth resolution and part per million level detection limits. We have both GD-OES and GD-TOFMS instruments.
  • a Raman microscope, capable of also using the surface-enhanced and tip-enhanced Raman effects (SERS and TERS respectively). This can be used for stress mapping on a sub-micron spatial scale.
  • a high spatial resolution Secondary Ion Mass Spectrometer (SIMS), integrated within a dual beam SEM-FIB instrument. This is used for chemical imaging (including depth profiles) on a smaller spatial scale than can be accessed by the glow discharge instruments.

We maintain research interests in the use of radiofrequency pulsed glow discharges, in the application of glow discharge analysis to thin films and to molecular materials, in the coupling of time-resolved mass spectrometric detection to pulsed discharges and in the use of plasmonic effects to enhance Raman signals. We have custom made instruments which improve the lateral spatial resolution of a glow discharge one hundred times (from several millimeters to tens of microns), which permit the time-resolved mass spectral analysis of molecular species in afterglowing plasmas and which allow SIMS measurements with spatial resolutions down to 10 nm.

Laboratory for Mechanics of Materials and Nanostructures
Empa - Materials Science & Technology
Feuerwerkstr. 39
CH-3602 Thun

Tel.: +41 33 228 46 26
Fax.: +41 33 228 44 90

Homepage of the Laboratory for Mechanics of Materials and Nanostructures
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Head of Laboratory
Dr. Johann Michler
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