Laurent Roussel

Extreme high resolution scanning electron microscopy (XHR SEM) and beyond

For decades, high resolution scanning electron microscopes (SEM) have strived to offer improved performance in the high and low energy regimes. High energies have always been attractive, because they lead to sub-nanometer resolution without complex electron optics, especially when using a scanning transmission electron microscopy (STEM) mode in the SEM. Lower energies have caught the attention of microscopists, due to their increased surface sensitivity, minimized charging effects or reduced depth of radiation damage. While going to very low beam landing energies was demonstrated more than 20 years ago, keeping a nanometric spot-size below 1 keV proved to be a technological challenge. Only a few years ago did the first commercial SEM succeed in delivering sub-nanometer resolution at 1 kV, but with some restrictions. Recently, the introduction of the extreme high resolution (XHR) SEM has demonstrated subnanometer resolution in the entire 1 to 30 kV range, thanks to a monochromatized Schottky electron source that reduces the effects of chromatic aberrations at lower energies. Of at least equal interest is the fact that the same XHR SEM can take advantage of its optics, modularity, platform stability and cleanliness developments to explore new avenues, such as high resolution imaging at very low beam energies or up to 30 kV STEM-in-SEM. For the first time, complementary information from the very surface and internal structure at the true nanometer level is obtained in the same SEM.

Recent Advances in FIB Technology for Nano-prototyping and Nano-characterisation

Combined focused ion beam (FIB) and scanning electron microscopy (SEM) methods are becoming increasingly important for nano-materials applications as we continue to develop ways to exploit the complex interplay between primary ion and electron beams and the substrate, in addition to the various subtle relationships with gaseous intermediaries. We demonstrate some of the recent progress that has been made concerning FIB SEM processing of both conductive and insulating materials for state-of-the-art nanofabrication and prototyping and superior-quality specimen preparation for ultra-high resolution scanning transmission electron microscopy (STEM) and transmission electron microscopy (TEM) imaging and related in situ nanoanalysis techniques.

Low-Energy Focused Ion Beam Milling Provides Reduced Damage During TEM Sample Preparation

The combined focused ion beam (FIB) and scanning electron microscope (SEM), known as the DualBeam, is well-known for its unique ability to produce site-specific thin samples starting from bulk and then attaching the section to a transmission electron microscope (TEM) grid, all in-situ . It has been reported that producing a thin sample using a 30 kV gallium FIB creates surface damage several tens of nanometers deep. However, recent DualBeam technology improvements now enable the FIB to produce thin samples with a thickness well below 50 nanometers and deliver a tightly focused ion beam at an energy of 2 kV and below, which dramatically reduces the damage depth to as low as 1 to 2 nanometers in typical materials, such as silicon.

Ultra-low energy, high-resolution scanning electron microscopy

Traditionally, the use of high primary beam energies in the SEM (up to 30 keV) helps to minimise the diameter of the primary electron beam, and the best ‘resolution’ of a microscope tends to be specified on this basis.

Focussed ion beam fabrication of large and complex nanopatterns

The fabrication of nanopatterns with a focussed ion beam (FIB) has recently been expanded to more complex nanopatterns with large numbers of individual pattern elements and covering larger pattern areas. We present two examples of FIB-fabricated large and complex nanopatterns and describe the key aspects of the underlying process automation. The FIB-fabrication has been carried out on DualBeam™ instruments, which combine the FIB with a scanning electron microscope in one single instrument. We also present examples on how FIB-cross-sectioning and high-resolution electron microscopy can be applied to characterise the just fabricated nanopatterns in great detail.