Electron tomography combining ESEM and STEM: a new 3D imaging technique

This paper presents the development and the application of a new electron tomography technique based on STEM (Scanning Transmission Electron Microscopy) configuration in ESEM (Environmental Scanning Electron Microscopy). This combination provides a new approach for the characterization of the 3D structure of materials, as it optimizes a compromise between the resolution level of a few tens of nm and the large tomogram size due to the high thickness of transparency. The method is well adapted for non-conductive samples, and exhibits good contrast even for materials with low atomic number. The paper describes the development of a dedicated stage for this new tomography technique. Taking advantage of the size of the ESEM chamber, the range of tilt angles is not limited by the space around the sample. The performance of this device is illustrated through the three-dimensional characterization of samples issued from materials science and chosen to illustrate the results in resolution, contrast and thickness.