edfas.org 9 ELECTRONIC DEVICE FAILURE ANALYSIS | VOLUME 27 NO.2 depth of heavy Bi+ and Au+ ions ensures excellent depth resolution. To meet the demands of nanoanalytics or nanofabrication the sample stage position is measured with displacement interferometers using a highly stabilized helium-neon laser with ≤1 nm resolution. The precision and resolution of the interferometric measurement, combined with the capabilities of the hybrid positioning system, ensure accurate placement of the point of interest, with positioning increments ranging from just a few nanometers to the scale of wafers. The combination of LMAIS FIB, a laser interferometer stage with CAD-based navigation, and a magnetic-sector SIMS presents significant potential for automated workflows, particularly for buried defect review and residue detection (Fig. 1). This article details the key features and setup of this novel analytical ion microscope system, showcasing its application in correlative 2D and 3D imaging of microelectronics samples. The results demonstrate that this system represents a significant advancement in nanoanalytics, offering capabilities beyond conventional methodologies by integrating LMAIS technology with a stable stage and SIMS unit for highresolution analytical imaging. This study presents the results of correlative 2D and 3D imaging using the recently developed nanoanalysis system. The system, which integrates LMAIS technology, a stable laser interferometer-controlled stage, and a dedicated magnetic sector SIMS unit, demonstrates significant advancements over conventional methodologies for sample analysis. ENHANCED IMAGING CAPABILITIES The integration of LMAIS technology allows for the simultaneous emission and rapid switching between multiple ion species. This capability is particularly advantageous for applications requiring different ion species for specific tasks, such as using heavy ions like Bi+ or Au+ for delayering and lighter ions like Li+ or Si2+ for high-resolution imaging (Fig. 2). The ability to switch ions within seconds significantly improves workflow efficiency and flexibility. The high spatial resolution imaging achieved with lighter primary ions (Li+ or Si2+) (<20 nm) and the excellent depth resolution provided by heavy ions (Bi+ and Au+) enhance the system’s capability to generate detailed 3D reconstructions of samples (Fig. 3). In this example, delayering was performed using 35 keV Bi⁺ ions, while imaging was conducted with 35 keV Li⁺ ions. Heavy ions like Au⁺ and Bi⁺ have lower penetration into the sample compared to Ga⁺, resulting in smoother surfaces. The combination of high spatial resolution imaging with lighter primary ions (Li⁺ or Si2⁺) (<20 nm) and the excellent depth resolution provided by heavy ions (Bi⁺ and Au⁺) enhances the system’s capability to generate detailed 3D reconstructions of samples. A Python code was used to visualize the image data in 3D as a lateral cross-sectional view.[3] CORRELATIVE 2D AND 3D IMAGING Copper indium gallium selenide (CIGS) solar cells are high-efficiency, rigid or flexible thin-film photovoltaics. Rubidium (Rb) enrichment enhances their efficiency and stability by improving the charge carrier concentration as well as increasing grain growth and reducing crystallinity defects, leading to better carrier collection. This advancement makes CIGS a strong alternative to siliconbased solar cells. The combination of high-resolution ion Fig. 2 Bismuth and lithium ions are used alternately. Appropriate Bi beam milling strategies are effectively employed to ensure smooth and uniform delayering of the sample. Intermittent imaging with lithium ions delivers high-resolution images between respective milling steps. Fig. 3 3D nano-reconstruction of the sample using SE images acquired with ions from GaBiLi ion source. The precision of the laser interferometer stage ensures a perfect alignment of the acquired images, (FOV 5 µm).
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