Differential electron yield imaging with STXM

William A Hubbard; Jared J Lodico; Xin Yi Ling; Brian T Zutter; Young-Sang Yu; David A Shapiro; B C Regan

doi:10.1016/j.ultramic.2020.113198

Differential electron yield imaging with STXM

Ultramicroscopy. 2021 Mar:222:113198. doi: 10.1016/j.ultramic.2020.113198. Epub 2020 Dec 30.

Authors

William A Hubbard¹, Jared J Lodico¹, Xin Yi Ling¹, Brian T Zutter¹, Young-Sang Yu², David A Shapiro², B C Regan³

Affiliations

¹ Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA; California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA.
² Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
³ Department of Physics and Astronomy, University of California, Los Angeles, CA 90095, USA; California NanoSystems Institute, University of California, Los Angeles, CA 90095, USA. Electronic address: regan@physics.ucla.edu.

Abstract

Total electron yield (TEY) imaging is an established scanning transmission X-ray microscopy (STXM) technique that gives varying contrast based on a sample's geometry, elemental composition, and electrical conductivity. However, the TEY-STXM signal is determined solely by the electrons that the beam ejects from the sample. A related technique, X-ray beam-induced current (XBIC) imaging, is sensitive to electrons and holes independently, but requires electric fields in the sample. Here we report that multi-electrode devices can be wired to produce differential electron yield (DEY) contrast, which is also independently sensitive to electrons and holes, but does not require an electric field. Depending on whether the region illuminated by the focused STXM beam is better connected to one electrode or another, the DEY-STXM contrast changes sign. DEY-STXM images thus provide a vivid map of a device's connectivity landscape, which can be key to understanding device function and failure. To demonstrate an application in the area of failure analysis, we image a 100 nm, lithographically-defined aluminum nanowire that has failed after being stressed with a large current density.

Keywords: Electron yield; Failure analysis; STXM; Scanning transmission X-ray microscopy; TEY; XBIC.

Grants and funding

S10 RR023057/RR/NCRR NIH HHS/United States