The Trends of In Situ Focused Ion Beam Technology: Toward Preparing Transmission Electron Microscopy Lamella and Devices at the Atomic Scale

Abstract

The increased complexity and scaling down of electronic devices lead to great challenges in extracting an interesting nanoscale area of the device for transmission electron microscopy (TEM) characterization. The traditional TEM sample preparation methods, such as electrolytic polishing, can not precisely process a specific area of the device. Focused ion beam (FIB) technology is an advanced in situ specimen preparation method for TEM. FIB can not only locate specific position and mill a TEM sample with the nanoscale resolution, but also manipulate the sample in a controlled manner in real time. With the development of electronic devices, variations, and optimizations of the FIB method for advanced devices with new structures have been reported. In this review, the TEM sample preparation methods for fin field‐effect transistor, high electron mobility transistor, enhanced dynamic random‐access memory, and 2D material‐based devices are discussed. Their advantages, disadvantages, and an overview of the applications are summarized. Based on current research, future research directions for enhancing the quality of TEM samples are suggested.

The 3D Controllable Fabrication of Nanomaterials with FIB-SEM Synchronization Technology

“…Additionally, FIB-SEM is widely used in the characterization of material composition and 3D microanalyses, by combining with a mass spectrometer [65,66]. The traditional preparation methods for bulk TEM samples are mechanical thinning, electrolytic polishing, and the ion milling technique [15], and their low success rate limits the application of TEM. FIB technology effectively improves the success rate of TEM sampling up to 95% by combining real-time SEM monitoring and a nanomanipulator [67].…”

“…Micro heating plate devices can provide a stable and controllable environment for investigating materials at different temperatures, allowing for in situ observations of the thermal behavior, phase transformations, and crystallography and composition changes [71]. High density and uniformity in material preparations such as metals, ceramics, and composite The traditional preparation methods for bulk TEM samples are mechanical thinning, electrolytic polishing, and the ion milling technique [15], and their low success rate limits the application of TEM. FIB technology effectively improves the success rate of TEM sampling up to 95% by combining real-time SEM monitoring and a nanomanipulator [67].…”

“…From then on, FIB has developed by improving the optical systems, expanding its application, and integrating with other systems. In the late 1980s, the eutectic alloy ion source promoted the performance of FIB greatly and expanded its applications in microelectronics, material analysis, device characterization, and other fields [ 4 , 13 , 14 , 15 ]. In the 1990s [ 16 ], SEM was combined with FIB to reduce sample damage and obtain sample imaging with a higher resolution.…”

“…In the 1970s, the focusing system of a FIB was very single, with one lens primarily for ion imaging. It was developed to a two-stage lens system to obtain a higher resolution in the 1980s, which enlarged the FIB applications in micro-analyses, micro-machining, and material modification [ 15 , 21 , 22 ]. Compared to in-lens deflectors and post-lens deflectors, two pre-lens deflectors are mostly used to reduce the chromatic aberration, in combination with the dynamic focusing system and octupole stigmator [ 23 ].…”

“…By integrating APT, a sharp tip with a radius of curvature less than 50 nm can be formed using a sample thinning technique and the polishing of constantly small beams [ 37 ]. As the available TEM sample thickness using a FIB ranges from the micrometer scale to less than 50 nm [ 15 ], a 1–2 keV low-energy Ga ion beam or low-energy Ar ion beam [ 40 , 41 ] will be needed to decrease the sample damage induced by a high energy ion beam. GIS has been shown to enhance FIB etching by using auxiliary gases [ 26 ], such as Cl 2 , I 2 , and XeF 2 , to react with sputtering atoms and form gaseous substances.…”