Focused Ion Beam Preparation of Specimens for Micro-Electro-Mechanical System-based Transmission Electron Microscopy Heating Experiments

Abstract

Micro-electro-mechanical systems (MEMS)-based heating holders offer exceptional control of temperature and heating/cooling rates for transmission electron microscopy experiments. The use of such devices is relatively straightforward for nano-particulate samples, but the preparation of specimens from bulk samples by focused ion beam (FIB) milling presents significant challenges. These include: poor mechanical integrity and site selectivity of the specimen, ion beam damage to the specimen and/or MEMS device during thinning, and difficulties in transferring the specimen onto the MEMS device. Here, we describe a novel FIB protocol for the preparation and transfer of specimens from bulk samples, which involves a specimen geometry that provides mechanical support to the electron-transparent region, while maximizing the area of that region and the contact area with the heater plate on the MEMS chip. The method utilizes an inclined stage block that minimizes exposure of the chip to the ion beam during milling. This block also allows for accurate and gentle placement of the FIB-cut specimen onto the chip by using simultaneous electron and ion beam imaging during transfer. Preliminary data from Si and Ag on Si samples are presented to demonstrate the quality of the specimens that can be obtained and their stability during in situ heating experiments.

In‐situ Transmission Electron Microscope Techniques for Heterogeneous Catalysis

“…[47] With the development of high temperature-resistant materials, the working temperature could reach more than 1500°C. [48][49][50] Recently, Pérez et al reported a newly-designed micro-heating system with ultra temporal-stability, which kept the heating sample at constant z-position (no bulging) up to 700°C and allowed EDX acquisition in the TEM up to 1000°C. [16,51] With the help of precision machining technology and MEMS technology, a special holder equipped with a nanoreactor can be manufactured for in-situ TEM study, which allows gases to be introduced and sealed within the reactor (illustrated in Figure 2c).…”

A method of Ga removal from a specimen fabricated on MEMS-based chip for in-situ transmission electron microscopy

“…In recent years, as the use of microelectromechanical systems (MEMS)-based chips for in situ TEM experiments increases, the preparation of specimens becomes even more challenging. One of the most widely used methods is to fabricate thin lamellae via focused ion beam (FIB) (Duchamp et al, 2014;Mele et al 2016;Vijayan et al 2017). This method has the advantage of being able to fabricate a specimen with a uniform thickness and the entire specimen preparation is completed only within the FIB.…”

“…However, the supporting lm in the chip may be torn or the surface of specimen may be damaged during FIB milling. Also, lift-out for positioning the lamella on MEMS chips performed inside the FIB (e.g., in-situ lift-out (INLO)) requires multiple and complex manipulation and an special inclined stage that minimizes the ion ux experienced by the chip during FIB milling (Duchamp et al, 2014;Vijayan et al 2017;Pivak et al 2018).…”

Evaluation of ion/electron beam induced deposition for electrical connection using a modern focused ion beam system

“…Therefore, FIB has been widely used to fabricate specimens for transmission electron microscopy (TEM). In particular, FIB sampling method becomes more important in micro-electromechanical system (MEMS)-based in situ TEM (Mele et al 2016;Vijayan et al 2017) in which we can observe real-time microstructural changes influenced by external stimuli such as electrical current and thermal and mechanical stress. For in situ TEM with electrical MEMS chips, the formation of a conducting path with low electrical resistance is required to connect TEM specimens to the electrodes in a MEMS chip.…”