Method of Ga removal from a specimen on a microelectromechanical system-based chip for in-situ transmission electron microscopy.

In-situ transmission electron microscopy (TEM) holders that employ a chip-type specimen stage have been widely utilized in recent years. The specimen on the microelectromechanical system (MEMS)-based chip is commonly prepared by focused ion beam (FIB) milling and ex-situ lift-out (EXLO). However, the FIB-milled thin-foil specimens are inevitably contaminated with Ga ions. When these specimens are heated for real time observation, the Ga ions influence the reaction or aggregate in the protection layer. An effective method of removing the Ga residue by Ar ion milling within FIB system was explored in this study. However, the Ga residue remained in the thin-foil specimen that was extracted by EXLO from the trench after the conduct of Ar ion milling. To address this drawback, the thin-foil specimen was attached to an FIB lift-out grid, subjected to Ar ion milling, and subsequently transferred to an MEMS-based chip by EXLO. The removal of the Ga residue was confirmed by energy dispersive spectroscopy.