A German research institute active in metrology has developed a cantilever solution to improve 3D measurements sensitivity in atomic force microscopy.
Today's atomic force microscopy, or AFM for short, is faced with the challenge of reliably measuring three-dimensional structures. Up to now, this has not worked completely flawlessly: commercially available cantilevers, that is the sensing element of an AFM, react unbalanced when they are exposed to forces of the three spatial dimensions. Researchers of the German institute are solving this problem with new cantilevers: thanks to their new structure, they react more sensitively to three-dimensional influences and do not slip when scanning slopes of different gradients.
Atomic force microscopy enables us to visualize the world of atoms, DNA strands & viruses. With increasing pressure to innovate, there is today a desire to detect even smaller structures and components very precisely, as the size of the items is continuously becoming smaller. In the semiconductor industry, for example, it must be possible to control the production processes of novel three-dimensional complex chip structures. The cantilevers used for this purpose show an anisotropy with regard to their stiffness, which can lead to uncontrollable slipping on the touched object. Furthermore, current cantilevers for thin tips show a low sensitivity due to the system-immanent combination of a flexible tip and torsionally stiff cantilevers.
In order to measure 3D structures accurately and non-destructively, three-dimensional AFM is required. The cantilever developed for this purpose at the German research institute has been extended by solid state joints. Different types of joints are available. One of them can be seen in the picture. The different areas allow a balanced torsion or bending with improved sensitivity. If the tip passes over a step or a slope during the measurement, the newly developed shaft gives way and the contour of the object can be interpreted correctly by the measuring device. This new design can be installed with little development effort in the future in conventional instruments.
Application areas for the new cantilever are general non-destructive testing of complex nanostructures, lithography masks, surface porosity or biological samples.
The principle of a cantilever with solid joints has been re-implemented. A German patent application is pending. The research institute is offering licenses and is interested in the joint further development in research cooperation agreements with partners as manufacturers of cantilevers for AFM. Current state of development is a functional model.