Ricerc@Sapienza

Correlative microscopy is an approach which benefits from imaging of the same object by different techniques. Correlation between the data, measured by two or more independent methods, can provide a piece of further information about the sample, which could be too complicated to analyze by those methods separately.

Correlative imaging by atomic force microscopy (AFM) and scanning electron microscopy (SEM) is very challenging due to the differences in coordination systems, spatial resolution, scanning nonlinearities,
and other effects, which cannot be simply corrected by post-processing. Novel technique Correlative Probe and Electron Microscopy (CPEM) overcomes these problems and enables real correlative imaging.

CPEM enables simultaneous surface characterization of a region of interest by SEM and AFM at the same time and in the same coordinate system. The electron beam is focused close to the stationary AFM tip. Subsequently, the scanning is provided by the piezo scanner with a mounted sample. Neither the e-beam nor the AFM probe is moving during CPEM image acquisition. Simultaneous sampling of SEM and AFM signals with known constant offset and identical pixel size ensures that the analysis is performed on the same surface at the same time and can be directly used for correlative imaging.

CPEM approach can combine and directly correlate several different signals from AFM and SEM (topography, cAFM, SE, BSE, CL, EBIC, etc.) to obtain comprehensive sample analysis. In particular:

• CPEM provides multidimensional correlation imaging – images from a Scanning Electron Microscope are extended into 3D.
• Using CPEM, it is possible to quickly and accurately distinguish the topographic and the material contrast in SEM images.
• CPEM correlates, in an appropriate fashion, two or more SEM signals with the measured topography such as SE, BSE, EBIC, etc.
• CPEM makes it possible to measure AFM and SEM simultaneously  under the same specimen conditions, at the same measurement speed, etc.
• The combined AFM and SEM scanning system enables an accurate image correlation, elimination of drift and other inaccuracies

================================

The platform includes:

LiteScope™,  an Atomic Force Microscope (AFM) by Nenovision (https://www.nenovision.com) carefully designed for working in high vacuum conditions and for easy integration into various scanning electron microscopes (SEM). Combination of such complementary techniques like AFM and SEM enables it to take advantage of both commonly used microscopy techniques. The complex sample analysis including surface topography, roughness, height/depth profiling or local conductivity can be obtained by LiteScopeTM using different replaceable probes.

Vega™, a Scanning Electron Microscope (SEM) by Tescan (https://www.tescan.com/), 4th generation Scanning Electron Microscope, with capabilities not only to perform correrlative microscopy with the LiteScope, but also to  combines SEM imaging and live elemental composition analysis in a single window of TESCAN’s Essence™ software. This combination significantly simplifies acquisition of both morphological and elemental data from the sample, making VEGA SEM an efficient analytical solution for routine materials inspection in quality control, failure analysis and research labs.software