9 July 2009

3-D nano measurements

When it comes to micro and nano structures, precision is the name of the game.

Manufacturers must construct and assemble these structures under very precise guidelines, so in the end, the overall system will function smoothly. That mean details are important.

The micro probe used in the micro-nano CMM measures the form and the spacing of two reference spheres with diameters of 2 millimeters each.

Along those lines, there is now a metrological scanning probe microscope in development that can act as a micro and nano coordinate measuring instrument, said researchers at the Physikalisch-Technische Bundesanstalt (PTB) in Braunschweig, Germany. This allows dimensional quantities with nanometer resolution also to undergo measurement on three-dimensional objects in an extraordinarily large measurement range of 25 mm x 25 mm x 5 mm. The new device is already extensively seeing use at PTB for calibration orders from industry and research.

Components with structures in the micro- and nanometer range are seeing increasing use in industry, so dimensional metrology on such structures is becoming increasingly important. To meet the increasing requirements for 3-D measurements of micro and nano structures, researchers incorporated 3-D measuring probes in a metrological scanning probe microscope based on a commercial nano-positioning system with integrated laser displacement sensors from the company SIOS Messtechnik GmbH. The new functionalities given by the measuring probe and the software extend the scanning probe microscope to a metrological micro/nano coordinate measuring machine (CMM), which also allows 3-D measurements conforming to standards performed on micro and nano structures.

International intercomparisons on step-height standards and lattice structures show the measuring system is one of the most precise of its kind. For step heights, measurement uncertainties in the subnanometer range—and for measurements of the mean structure spacing on extensive lattice standards even in the range of 10 picometers—occurred and then compared with optical diffraction measurements.

The new measuring instrument is available for dimensional precision measurements with nm resolution on 3-D micro and nano structures such as micro gears, micro balls, hardness indenters, and nano lattice standards, as well as for comparisons of measures. It can also serve as a platform for research and development tasks. It is an important link between nano, micro, and macro coordinate metrology.

For related information, go to www.isa.org/instruments.