Scalable and number-controlled synthesis of carbon nanotubes by nanostencil lithography

Abstract

Controlled synthesis and integration of carbon nanotubes (CNTs) remain important areas of study to develop practical carbon-based nanodevices. A method of controlling the number of CNTs synthesized depending on the size of the catalyst was characterized using nanostencil lithography, and the critical dimension for the nanoaperture produced on a stencil mask used for growing individual CNTs was studied. The stencil mask was fabricated as a nanoaperture array down to 40 nm in diameter on a low-stress silicon nitride membrane. An iron catalyst used to synthesize CNTs was deposited through submicron patterns in the stencil mask onto a silicon substrate, and the profile of the patterned iron catalyst was analyzed using atomic force microscopy. The feasibility toward a scalable, number-, and location-controlled synthesis of CNTs was experimentally demonstrated based on the diameter and geometry of the apertures in the stencil mask.

Nanoscale Patterning of Carbon Nanotubes: Techniques, Applications, and Future

“…Choi et al were able to push shadow mask patterning down to nanometer resolution by using a low-stress silicon nitride membrane shadow mask. [249] They deposited Fe catalyst via electron beam evaporation through nanoapertures on the shadow mask, which had diameters down to 40 nm and spacing down to 260 nm (Figure 12a). Significant blurring occurred, with some deposited catalyst island diameters being more than double the respective nanoaperture diameter.…”

“…Reproduced under a CC‐BY 4.0 license. [ 249 ] Copyright 2013, The Authors, published by Springer Nature. b) AFM image of catalyst metal layer on substrate patterned through a self‐assembled nanosphere mask.…”

“…Diblock copolymers can be phase separated into nanoscale periodic patterns under controlled conditions. These self-assembled diblock copolymer patterns can be used to pattern CNT growth catalyst by inserting the metal catalyst into one of the [249] Copyright 2013, The Authors, published by Springer Nature. b) AFM image of catalyst metal layer on substrate patterned through a self-assembled nanosphere mask.…”

“…a) Using a shadow mask for nanoscale patterning of CNT growth catalyst. Reproduced under a CC-BY 4.0 license [249]. Copyright 2013, The Authors, published by Springer Nature.…”

FIB Secondary Etching Method for Fabrication of Fine CNT Forest Metamaterials

“…Patterned growth of CNTs on the scale of tenths of micrometers has been successfully reported on silica [ 12 – 14 ], silicon substrates [ 15 ], and also on predeposited catalyst [ 16 – 18 ]. On the other hand, the patterning of predeposited catalyst at the nanoscale, which would enable uniform, vertically aligned SWNT forest growth on various shapes of nanosize structures, is still challenging and is yet to be achieved [ 17 , 19 – 21 ]. High-quality CNT structures with various shapes were achieved by utilizing different fabrication methods.…”