Compact Sub Micro-resolution X-ray Microscope Based on Carbon Nanotube FE-SEM

Abstract

Generally, nano-resolution X-ray imaging has been achieved using synchrotron radiation facility. The spatial resolution (below 100 nm) achieved with a Fresnel zone plate for focusing the X-ray in SPring-8 lately. We have developed a compact composite of field emission-scanning electron microscope (FE-SEM) with a single isolated multi-walled carbon nanotube (CNT) electron source in our previous study. The spatial resolution of SEM image was estimated as ≃ 10 nm. This result indicates that the electron source we developed is suitable for a point-like X-ray source. We developed two kinds of X-ray microscope; projection-type X-ray microscope (PXM) and transmission-type X-ray microscope (TXM) in this study. The X-ray microscope based on the CNT-FE-SEM was constructed with a metal target for the X-ray source. Developing our X-ray microscope has been miniaturized to a compact size so that it can be placed on a desk. Moreover, the spatial resolution of 400 nm achieved the theoretical resolution limit. Because there is resolution limit by the acceleration voltage of 17 kV for the focused electron beam spot, the spatial resolution is an order of the electron penetration depth. The present study shows a potential that the CNT-based X-ray microscope would be applied to various field studies including the scene of an archaeological site excavation and future planet search. [DOI: 10.1380/ejssnt.2018.84]