A multiwalled carbon nanotube (MWCNT) field emitter is developed as the electron source for a microcolumn-based field-emission scanning electron microscope (SEM). A MWCNT is first attached onto a tungsten (W) support tip using the nanomanipulator in the SEM. Then, an electrical bias is applied between the MWCNT field emitter and W tip to improve the contact between them, which lowers the threshold voltage for field emission. An emission current stability test showed that the emission current is stable. The fabricated MWCNT emitter exhibits a high emission current of 12 μA and sample current of around 2 nA, even at a low tip bias of 350 V in the microcolumn. The tip bias is much lower, and the sample current is higher than the equivalent values reported for W tips. The authors acquired images of a 1000-mesh copper grid using the microcolumn-based SEM with a MWCNT field emitter as the source. Our results suggest that MWCNTs should be considered a promising candidate as an electron source for microcolumns.

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We have constructed a new nanomanipulator (NM) in a field emission scanning electron microscope (FE-SEM) to fabricate carbon nanotube (CNT) tip to precisely adjust the length and attachment angle of CNT onto the mother atomic force microscope (AFM) tip. The new NM is composed of 2 modules, each of which has the degree of freedom of three-dimensional rectilinear motion x, y and z and one-dimensional rotational motion θ. The NM is mounted on the stage of a FE-SEM. With the system of 14 axes in total which includes 5 axes of FE-SEM and 9 axes of nano-actuators, it was possible to see CNT tip from both rear and side view about the mother tip. With the help of new NM, the attachment angle error could be reduced down to 0º as seen from both the side and the rear view, as well as, the length of the CNT could be adjusted with the precision using electron beam induced etching. For the proper attachment of CNT on the mother tip surface, the side of the mother tip was milled with focused ion beam. In addition, electron beam induced deposition was used to strengthen the adhesion between CNT and the mother tip. In order to check the structural integrity of fabricated CNT, transmission electron microscope image was taken which showed the fine cutting of CNT and the clean surface as well. Finally, the performance of the fabricated CNT tip was demonstrated by imaging 1-D grating and DNA samples with atomic force microscope in tapping mode.

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