Correlative Microscopy in 3D: Helium Ion Microscopy-Based Photogrammetric Topography Reconstruction Combined with in situ Secondary Ion Mass Spectrometry

The chemical or elemental analysis
of samples with complex surface topography is challenging for secondary
ion mass spectrometry (SIMS), if the three-dimensional structure of
the sample is not taken into account. Conventional 3D reconstruction
of SIMS data assumes a flat surface and uniform sputtering conditions,
which is not the case for many analytical applications involving micro-
and nanosized particles, composites, or patterned materials. Reliable
analysis of such samples requires knowledge of the actual 3D surface
structure to correctly reconstruct the SIMS 3D maps. To this end,
we introduce the use of photogrammetric 3D topography reconstruction
from scanning helium ion microscopy (HIM) correlated with in situ SIMS data for the reconstruction of 3D SIMS data.
The HIM and SIMS data are acquired under in situ conditions
in a Zeiss ORION NanoFab HIM using a novel SIMS analyzer. We successfully
tested the applicability of the approach to generate 3D models of
different samples and show that the combination of SIMS and 3D topography
is able to provide insights into the influence of the sample topography
in a single instrument and with a single ion column and hence without
the need for ex-situ sample analysis or additional instrumentation.
These findings offer a path toward ion-based correlative 3D spectromicroscopy
(3D-HIM-SIMS) and suggest that many combinations of charged particle
based P3D (SEM, HIM) and analytical microscopy techniques, such as
SIMS, energy-dispersive X-ray spectroscopy (EDX), or ionoluminescence/cathodoluminescence
(IL/CL), can be used for correlative microscopy in 3D.