ID-1-P-3172 Integrated Raman microscope with FIB-SEM

Using multiple microscope techniques is an effective strategy to obtain more information about a samples properties. This allows researchers to gain new insights or to employ new strategies for analysis. However using different microscopes leads to new problems, moving the sample between systems often results in contaminations and deformations. Furthermore this process is often time consuming and the researcher has to take care not to lose the region of interest. Therefore we present a system employing an integrated Raman microscope in a dual beam Focused Ion Beam – Scanning Electron Microscope (FIB - SEM), as shown in figure 1.

This system combines chemical and high resolution morphological analysis with a sample processing modality. The combination of FIB with Raman allows us to investigate the redeposition of removed material and to analyse defects that occur through ion implantation. Sample analysis is performed with correlative SEM and Raman microscopy, this provides high resolution morphological information and a compound specific image. The combined system provides more information and new strategies for analysis in the material and biological sciences.

The integration of microscopes does give rise to new challenges mainly concerning engineering aspects. Implementation of the Raman objective in a confined space requires a careful design of the objective pickup system. Furthermore the vacuum pressure in the FIB chamber has to remain stable, which requires the use of coupling windows and cable feedthroughs. Ultimately the Raman microscope functions as an add on module for the FIB-SEM which means that it may not place any restrictions on its operation.

As a first project of immediate interest is the analysis of multimodal labels, i.e. labels suitable for both optical and electronic imaging. These labels consist of a gold nanoparticle with an adsorbed fluorescent dye to provide a high electron scattering and SERS signal. Multimodal labels are of interest for biological applications because the SEM contrast is limited in organic matter due to charging effects. Furthermore these labels are very promising as an aid for correlating the Raman and SEM images.