Reflection mode scanning near-field optical microscopy analyses of integrated devices

Ultra-large-scale integrated devices have been investigated by a reflection mode scanning near-field optical microscope designed for semiconductor ana lyses. Although it could be found that imaging the reflectivity of metal st ructures buried underneath thin, optically transparent passivation layers i s practicable, shading of the reflected light by the SNOM probe complicated the interpretability of the achieved results. This issue has been overcome by using the SNOM probe as both illumination source and detector, simultan eously. The application of focused ion beam milling to the probes has allow ed the increase of the transmittivity of the probes to such an extent that coated fibres could be utilized and the interpretability of the results cou ld be enhanced. Furthermore, the investigated structures are of great inter est for an investigation of z-motion artefacts, as the presence of the poli shed passivation layers allows topographical influences to be distinguished from pure optical contrast.