Traceable measurements of small forces and local mechanical properties

Abstract

Measurement of local mechanical properties is an important topic in the fields of nanoscale device fabrication, thin film deposition and composite material development. Nanoindentation instruments are commonly used to study hardness and related mechanical properties at the nanoscale. However, traceability and uncertainty aspects of the measurement process often remain left aside. In this contribution, the use of a commercial nanoindentation instrument for metrology purposes will be discussed. Full instrument traceability, provided using atomic force microscope cantilevers and a mass comparator (normal force), interferometer (depth) and atomic force microscope (area function) is described. The uncertainty of the loading/unloading curve measurements will be analyzed and the resulting uncertainties for quantities, that are computed from loading curves such as hardness or elastic modulus, are studied. For this calculation a combination of uncertainty propagation law and Monte Carlo uncertainty evaluations are used.

Calibrating the Stiffness of Afm Cantilevers via Instrumented Indentation Devices

“…Experiments were performed using the Ultra Hardness Nano Tester from Anton Paar. The instrument has been calibrated traceably as described in [14]. The resulting linear calibration constants for the force and depth sensor have a relative uncertainty of 12 % and 1 %.…”

Independent analysis of mechanical data from atomic force microscopy

“…All this was done to convert the quadrant photodiode detector signal into force signal. Note that there are many well-developed methods available for these operations [11][12][13][14][15][16], however, as the aim of this work was to demonstrate data processing capabilities, not to provide traceable mechanical properties results, no special care was taken to use a more accurate force and a tip-sample displacement calibration methodology.…”

Development of reference materials for the investigation of local mechanical properties at the nanoscale

“…The UNHT was calibrated traceably using an interferometer for the calibration of the depth sensor and a calibrated atomic force microscope (AFM) cantilever as a transfer standard for the force sensor. The cantilever was calibrated on a mass comparator, which is in turn calibrated by the national etalon . Tests were performed with linear loading with maximum loads in the range of 1 to 100 mN.…”

“…The cantilever was calibrated on a mass comparator, which is in turn calibrated by the national etalon. [7] Tests were performed with linear loading with maximum loads in the range of 1 to 100 mN. The loading time was kept fixed at 30 s. Each test was repeated approximately 20 to 30 times for statistical evaluation.…”