Forgery-proof Object Identification
Unique nano-seals allow for forgery-proof object identification. Due to a combination of ion irradiation and simultaneous co-deposition of metal atoms a unique surface pattern is created. Its manufacturing process and its size of only a few square micrometers make it impossible to be reproduced, thus creating a forgery-proof identifier.
Identifying an original object in a forgery-proof way has been a demanding task since many years. Despite the fact that there is a vast diversity of different approaches reaching from RFID-chips to color-coded micro particles, all of these techniques can be overrode with reasonable efforts. This is a major drawback in authenticating security-relevant or valuable objects that are indistinguishable to the bare eye.
The innovative method applies a random chemo-topological pattern to an object's surface thus creating a unique fingerprint. A digital copy of that fingerprint is then taken and made available through a database. The embedded features are so small that it is impossible to image or reproduce them by conventional microscopic respectively litographic means so the readout has to be carried out with a scanning electron microscope (SEM). This is an important feature because an SEM image is not simply an image of the surface topology but a convolution of the surface topology and the surface composition - which again is randomly influenced by the co-deposited metal atoms. So just using a negative stamp to create a copy of the pattern on a new surface will not transfer the whole information stored in the seal. The structures can be varied within a wide range of sizes, shapes and positions making this technique very flexible. Generally the affected region is of the order of only a few square micrometers making its disruptive impact on the surface negligible but can also be applied in large-scale if desired.
SEM image of a wave-and-point pattern that has been created with the proposed technique. The circular shape has been produced by a litographic PMMA mask and can be adjusted to any desired shape. The right-hand side of the picture shows a close-up of the center region. The marker length at the bottom always corresponds to 1 micrometer. (Source: H. Hofsäss)
To be used for forgery-proof labeling of semiconductors, diamonds, vital electronic components (e.g. in airplanes), etc. The surface materials include (but are not limited to) silicon, carbon, carbide forming metals, glass, sapphire ...
The method has been successfully tested in the laboratory. Results show that unique and simultaneously clearly distinguishable patterns can be generated in any number. When using standard ion sources these patterns can be applied within a few seconds and later be read out with an electron microscope in a comparable time. In addition, the presented technique can easily be integrated into existing manufacturing processes.
Designing self-organized nanopatterns on Si by ion irradiation and metal co-deposition