Material interface detection based on secondary electron images for focused ion beam machining

• Published in: Ultramicroscopy Vol. 184; no. Pt B; pp. 37 - 43
• Main Authors: Joe, Hang-Eun, Lee, Won-Sup, Jun, Martin B. G., Park, No-Cheol, Min, Byung-Kwon
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-01-2018
• Subjects: Endpoint detection; Image contrast; Ion-induced secondary electron; Multilayer; Surface characterization; Multilayer; Ion-induced secondary electron; Surface characterization; Endpoint detection; Image contrast
• ISSN: 0304-3991; 1879-2723
• DOI: 10.1016/j.ultramic.2017.10.012

•A strategy of material interface detection was proposed for FIB process control.•Gray-levels of ion-induced secondary electron images were monitored to analyze the surface characteristics of the ion-sputtered area.•Peaks on the graph of average and skewness coefficient of gray-levels was analyzed to detect the interlayer interface as endpoints for the FIB process.•The proposed strategy was verified by fabrication of nanostructures on flat and curved substrates of the multilayered target with high precision.
A method for interface detection is proposed for focused ion beam (FIB) processes of multilayered targets. As multilayers have emerged as promising structures for nanodevices, the FIB machining of multilayers has become a challenging issue. We proposed material interface detection by monitoring secondary electron (SE) images captured during the FIB process. The average of the gray-levels and the skewness coefficient of gray-level histograms of the SE images were evaluated to recognize endpoints for the FIB processes. The FIB process control with the proposed method was demonstrated by fabricating the nanostructures on the multilayered target without thickness information. It was also demonstrated on a curved surface. Grooves with a desired depth into the target and an aperture as an opening window were precisely fabricated by the FIB process control. The proposed strategy of the FIB process can be used for complex substrates such as curved or flexible targets.