Large area 3D tomography with femtosecond laser slicing

3D tomography is a commonly used tool on FIB systems to analyse material characteristics in multiple dimensions. The method is mainly used utilizing ion beams and the volume being characterized is limited by the maximum removal rate of the used beam. If a material characteristic e.g. grain size requires a large volume to be investigated for a quantitative analysis, creating cross-sections with a high removal rate laser beam can resolve this challenge. As the removal rate can be much higher compared to ion beams, a large volume/cross-sectional area is accessible. Furthermore, it is possible to reveal buried regions within in the material and execute the tomography on a region deeply below the sample surface.

A workflow for creating 3D tomography data from laser prepared cross-sections is started by selecting a region of interest as the tomography site and prepared by removing the surrounding material, creating a protruding nose as the volume to be investigated. Utilizing a specific scanning strategy for the laser beam, a first slice of the material is created, revealing the underlying microstructure (Figure 1). EBSD analysis can be carried out in parallel without the need to retract the camera for every slice, since the special setup of the ZEISS system features a dedicated laser preparation chamber, which eliminates detector contamination during laser processing.