PTB News 1/2009 (5.7 MB) PTB News 1/2009, English edition, Issue April 2009
At PTB, a purely metrological scanning probe microscope has been developed into a micro-/nano coordinate measuring machine. This now allows dimensional quantities with nanometer resolution also to be measured on three-dimensional objects in an extraordinarily large measurement range of 25 mm x 25 mm x 5 mm.
Today, components with structures in the micro- and nanometer range are integrated in many products of daily life – from the micromechanical motion sensor to the computer chip. Compliance with the geometric tolerances of these small structures is in many cases decisive for smooth functioning of the overall system. Dimensional metrology on such structures is, therefore, of increasing importance. To meet the increasing requirements for 3D measurements of micro- and nanostructures, 3D measuring probes newly developed at PTB were incorporated in a metrological scanning probe microscope based on a commercial nano-positioning system with integrated laser displacement sensors. On that basis, the device control was extended by a software interface (I++ DME) independent of manufacturer and a standard measurement and evaluation software (Quindos 7.0) for coordinate measuring machines (CMM).
The new functionalities given by measuring probe and software extend the scanning probe microscope to a metrological micro/nano coordinate measuring machine (CMM) which also allows 3D measurements conforming to standards to be performed on micro- and nanostructures.
International intercomparisons on step-height standards and lattice structures have shown that the measuring system is one of the most precise of its kind worldwide. For step heights, measurement uncertainties in the subnanometer range have been reached and for measurements of the mean structure spacing on extensive lattice standards, uncertainties even in the range of 10 picometers have been reached and confirmed in comparison with optical diffraction measurements.
The new measuring instrument is available for dimensional precision measurements with nm resolution on 3D micro- and nanostructures such as micro gears, micro balls, hardness indenters and nano lattice standards as well as for comparisons of measures; moreover, it serves as a platform for research and development tasks. It is an important link between nano-, micro- and macro coordinate metrology.