NANOSTRUCTURED TEST SPECIMENS FOR COMBINED NEAR-FIELD MICROSCOPY (2012 - 2013)

Project coordinators: in France –Daniel Pailharey (AXESS TECH SARL), in Latvia –Juris Purāns

Near-field microscopy techniques are increasingly used in scientific laboratories, but still, highly qualified personnel are required to achieve good results. This technique, in particular AFM (atomic force microscope), can be used even more widely in industry, if, on the other hand, it would allow to characterize the chemical composition of the surface.

AXESS TECH has been distributing near-field microscopes in France for more than 10 years and is currently the coordinator of the international European project EUROSTARS, which involves two more companies (France, Germany) and a research laboratory from France. This program envisages the implementation of a prototype with new functions, which would combine two complementary methods: X-ray absorption analysis and near-field microscopy. In this method, the specimen is irradiated with X-rays and a local probe (AFM or SNOM) receives an optical or X-ray fluorescence signal emitted by the specimen during a surface scan.

Such a device is new and unique, which necessitates new type of nanostructured test specimens. It should be noted that the usual test specimens for near field measurements give only topography, but the new variant - also the chemical composition of the surface. OSMOSA Project partners are complementary to create new type test specimens and use the new combined microscope for testing.

The Latvian group has extensive experience in both X-ray absorption spectroscopy and the application of materials with the required properties. A prototype of this device is currently being assembled and AFM topographic test measurements are scheduled for the end of 2011.

To enter the commercialization phase, AXESS TECH would need another 2-3 years of additional work: design development, accurate test measurements to assess the sensitivity of the optical signal. To calibrate the new equipment, it is necessary to create a test specimen with known X-ray optical luminescence and topography properties. Therefore, after the completion of the EUROSTAR project, the French group needs cooperation with the Latvian EXAFS laboratory.

Thanks to the proximity of the microelectronics center (d'Aix en Provence), which is also connected with the Universities in Marseille, AXESS TECH can use the technical base needed to implement mask lithography, as well as to etch a topographic grid on specimens made in Riga (at ISSP UL). Quality testing will be performed by AXESS TECH.

The Latvian group undertakes to characterize these new test specimens using synchrotron radiation X-ray microscopy in the best centers in the world. Private companies have very difficult access to such exceptionally large synchrotrons, such as ESRF, HASYLAB, SOLEI, etc., but the Latvian EXAFS laboratory has rich experience and good access to these devices. ISSP UL employs world-class scientists who specialize in this methodology using synchrotron radiation.

We want to create two types of samples: Type 1 specimens consist of emission grid lines that will emit in the visible area of the spectrum; the reception of the optical signal will take place at the same time as the surface scan. As a result, there will be two complementary images - a topography and an optical response related to the composition of the material. Type 2 specimens will be made to receive an X-ray fluorescence signal in parallel with the topographic measurements and will allow the probe to be placed topographically over a selected sample point for X-ray fluorescence analysis (EDX).

In the third phase of this work, the test specimen could be further treated with an ion beam or an additional unique layer applied to it. In this case, the EDX analysis will provide information about the structure of the 3-dimensional test specimen.