Focused Ion Beam (FIB) Nanofinishing for Ultra-Thin TEM Sample Preparation

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The focused ion beam (FIB) has been a well-established tool in the semiconductor industry mainly for applications like integrated circuit repair and debugging, device modification and failure analysis. Advances in FIB technology in achieving a tighter focus and integrated analysis tools (scanning electron microscope [SEM], X-ray diffraction, etc.) have made micromachining by FIB more attractive for researchers. This is mainly due to its high-resolution, one-step maskless fabrication and possibility to work with a variety of materials and geometries (two-and three-dimensional). As is evident from Figure 7.1a, micro-sized logos of IIT Bombay and WinTechCONTENTS7.1 Introduction 155 7.2 FIB System 1577.2.1 Ion Source 159 7.2.2 Imaging 160 7.2.3 Sputtering 161 7.2.4 FIB-Induced Chemical Vapour Deposition 162 7.2.5 Material Self-Organisation 1647.3 TEM Sample Preparation 165 7.3.1 FIB for TEM Sample Preparation 1667.3.1.1 The H-Bar Technique 166 7.3.1.2 The Lift-Out Technique 1687.3.2 FIB-Induced Damage 170 7.4 Conclusions 172 Acknowledgements 173 References 174Nano, with nanometer features, are directly patterned, without using any mask, on silicon using FIB and imaged using SEM in the same setup. Figure 7.1b demonstrates patterning of an artistic castle on a Ni material. In addition to the nano-fabrication capability, the FIB can be further used to polish surfaces to attain low loss, highly reflective mirrors, typically required in micro-devices/components such as planar photodiodes, surface emitting lasers, optical interconnects, etc. [1]. The flexibility of the direct milling and the ion beam manipulation enables polishing along various orientations.