| AVS 56th International Symposium & Exhibition | |
| MEMS and NEMS | Thursday Sessions |
| Session MN+IJ+TR-ThA |
| Session: | Multi-scale Interactions of Materials and Fabrication at the Micro- and Nano-scale I |
| Presenter: | T. Dziomba, Physikalisch-Technische Bundesanstalt (PTB), Germany |
| Authors: | T. Dziomba, Physikalisch-Technische Bundesanstalt (PTB), Germany S. Gao, Physikalisch-Technische Bundesanstalt (PTB), Germany U. Brand, Physikalisch-Technische Bundesanstalt (PTB), Germany K. Herrmann, Physikalisch-Technische Bundesanstalt (PTB), Germany L. Koenders, Physikalisch-Technische Bundesanstalt (PTB), Germany |
| Correspondent: | Click to Email |
Apart from accurate determination of dimensional, i. e. geometric, features of small objects such as nanostructures and semiconductor structures, the quantitative determination of small forces in the range from µN (10-6 Newton) down to several ten pN (10-12 N) is essential for many research tasks. Applications range from force spectroscopy in nanobiotechnology to the determination of the mechanical properties of nanomaterials, biological structures and organic molecules. Most of these measurements are performed with scanning force microscopes (SFM) and cantilevers with integrated nanometric tips as probing elements. However the comparability of experimental results lack under the knowledge of cantilever stiffness and traceability of small forces.
With the help of special Metrology-SFMs as reference instruments at National Metrology Institutes (NMIs), a large variety of transfer standards as well as guidelines for characterization & dimensional calibration of SFM, the length traceability to the SI-unit meter has been successfully established for SFM in the past few years.
However, a similar traceability chain for the measurement of small forces still needs to be realized. NMIs face the challenge to expand the traceability chain down to small forces by developing special nanoforce primary standards. A further challenge is the development of transfer standards and/or measurement procedures which allow the user to conveniently calibrate cantilevers used for SFM and scanning force spectroscopy. Besides the deflection-calibration a simultaneous force-calibration of the cantilever is necessary.
The contribution describes the properties of a MEMS (Micro-Electro-Mechanical-System) comb drive actor which can be used as a force sensor. Traceable calibration of its stiffness is done using a nanoforce calibration device based on a high resolution compensation balance. The sensor used has a force resolution in the nN-range, a measurement range of up to 1 mN, a translation range of 8 µm and was used to quantitatively determine the stiffness of SFM cantilevers. Preliminary experiments demonstrate that the long-term stability of the sensor is better than 3.7×10-3 N/m (1 sigma ) over 1 hour. After careful traceable calibration of its stiffness, the MEMS sensor has the capability to determine the stiffness of a great variety of cantilever types (from 100 N/m down to 0.1 N/m) with high accuracy. Thus a new micro-force and stiffness transfer standard with nN force resolution is available for the traceable stiffness calibration of SFM cantilevers.