Lubomír Tuma

Improving SEM Imaging Performance Using Beam Deceleration

Beam Deceleration is a relatively simple method to reduce electron beam energy and improve imaging parameters such as resolution and contrast. The scanning electron microscope (SEM) uses a sharply focused electron beam to probe the specimen surface. The energy of the electrons forming such a probe is determined by the electrical potential of the electron source, referred to as accelerating voltage or high voltage (HV). No matter how many times the electrons are accelerated or decelerated inside the column, they leave the column with an energy corresponding to the high voltage. The high voltage is usually controllable within a range of 200 V to 30 kV for most commercially available SEMs, allowing the operator to select the electron beam energy suitable for the application. Imaging with very low electron beam energy has great importance, which is illustrated by SEM instrumentation development over the last few decades [1–2]. Low voltage microscopy is a topic discussed at most microscopy-related conferences these days, but generally, it is approached with an immersion lens and field emission gun (FEG) SEM system because of the better beam current densities. However, beam deceleration is also a means to bring low kV improvement to SEMs with thermionic electron sources.

Helios G4: Pushing the Limits of TEM Sample Preparation and STEM Resolution

Shrinking sizes of observed features and advancements in (S)TEM techniques requires higher quality TEM sample preparation as well as extended low-kV STEM-in-SEM analysis. In this contribution we present a new generation of the FEI Helios family, configured for ultimate sample preparation and improved STEM-in-SEM imaging. The main improvements to the system can be summarized in sample handling, improved electron and ion optics, and in the introduction of a brand new workflow combining advanced TEM sample preparation and high-resolution STEM imaging in a single instrument.