Crystalline defect analysis in epitaxial Si0.7Ge0.3 layer using site-specific ECCI-STEM

Han Han; Libor Strakos; Thomas Hantschel; Clement Porret; Tomas Vystavel; Roger Loo; Matty Caymax

doi:10.1016/j.micron.2021.103123

Crystalline defect analysis in epitaxial Si_0.7Ge_0.3 layer using site-specific ECCI-STEM

Micron. 2021 Nov:150:103123. doi: 10.1016/j.micron.2021.103123. Epub 2021 Jul 21.

Authors

Han Han¹, Libor Strakos², Thomas Hantschel³, Clement Porret³, Tomas Vystavel², Roger Loo³, Matty Caymax³

Affiliations

¹ imec, Kapeldreef 75, 3001, Leuven, Belgium. Electronic address: han.han@imec.be.
² Thermo Fisher Scientific, Vlastimila Pecha 12, 62700, Brno, Czech Republic.
³ imec, Kapeldreef 75, 3001, Leuven, Belgium.

PMID: 34343885
DOI: 10.1016/j.micron.2021.103123

Abstract

Electron channeling contrast imaging (ECCI) is a powerful technique to characterize the structural defects present in a sample and to obtain relevant statistics about their density. Using ECCI, such defects can only be properly visualized, if the information depth is larger than the depth at which defects reside. Furthermore, a systematic correlation of the features observed by ECCI with the defect nature, confirmed by a complementary technique, is required for defect analysis. Therefore, we present in this paper a site-specific ECCI-scanning transmission electron microscopy (STEM) inspection. Its value is illustrated by the application to a partially relaxed epitaxial Si_0.7Ge_0.3 on a Si substrate. All experiments including the acquisition of ECCI micrographs, the carbon marking and STEM specimen preparation by focused ion beam, and the in-situ-subsequent-STEM-in-scanning electron microscopy (SEM) characterization were executed in one SEM/FIB-based system, thus significantly improving the analysis efficiency. The ECCI information depth in Si_0.7Ge_0.3 has been determined through measuring stacking fault widths using different beam energies. ECCI is further utilized to localize the defects for STEM sample preparation and in-situ-subsequent-STEM-in-SEM investigation. This method provides a correlative 2.5D defect analysis from both the surface and cross-section. Using these techniques, the nature of different line-featured defects in epilayers can be classified, as illustrated by our study on Si_0.7Ge_0.3, which helps to better understand the formation of those detrimental defects.

Keywords: Crystalline defect analysis; ECCI information depth; Electron channeling contrast imaging; Scanning transmission electron microscopy in SEM; Site-specific FIB sample preparation.