In-Lens Band-Pass Filter for Secondary Electrons in Ultrahigh Resolution SEM

0508751 - ÚPT 2020 RIV CH eng J - Journal Article
Konvalina, Ivo - Mika, Filip - Krátký, Stanislav - Materna Mikmeková, Eliška - Müllerová, Ilona
In-Lens Band-Pass Filter for Secondary Electrons in Ultrahigh Resolution SEM.
Materials. Roč. 12, č. 14 (2019), č. článku 2307. E-ISSN 1996-1944
R&D Projects: GA TA ČR(CZ) TE01020118; GA TA ČR TE01020233; GA TA ČR(CZ) TN01000008
Institutional support: RVO:68081731
Keywords : band-pass filter of signal electrons * SE detection * trajectory simulations
OECD category: Electrical and electronic engineering
Impact factor: 3.057, year: 2019
Method of publishing: Open access
https://www.mdpi.com/1996-1944/12/14/2307/htm

Scanning electron microscopes come equipped with different types of detectors for the collection of signal electrons emitted from samples. In-lens detection systems mostly consist of several auxiliary electrodes that help electrons to travel in a direction towards the detector. This paper aims to show that a through-the-lens detector in a commercial electron microscope Magellan 400 FEG can, under specific conditions, work as an energy band-pass filter of secondary electrons that are excited by the primary beam electrons. The band-pass filter properties verify extensive simulations of secondary and backscattered electrons in a precision 3D model of a microscope. A unique test sample demonstrates the effects of the band-pass filter on final image and contrast with chromium and silver stripes on a silicon substrate, manufactured by a combination of e-beam lithography, wet etching, and lift-off technique. The ray tracing of signal electrons in a detector model predicate that the through-the-lens detector works as a band-pass filter of the secondary electrons with an energy window of about 3 eV. By moving the energy window along the secondary electron energy spectrum curve of the analyzed material, we select the energy of the secondary electrons to be detected. Energy filtration brings a change in contrast in the image as well as displaying details that are not otherwise visible.
Permanent Link: http://hdl.handle.net/11104/0299576