Researchers working in Princeton University improved fabrications methods in nanotech. From their article (citations omitted) in Nature Nanotechnology (http://www.nature.com/nnano):

Owing to their fascinating physical and chemical properties, the use of carbon nanotubes (CNTs) has been extensively pursued in nanodevices such as microelectromechanical systems (MEMS), although efforts to date have primarily focused on demonstrations of individual CNTs and single nanodevices. For example, a suspended nanotube has been used as a device element of tuneable electromechanical oscillators, sensors, non-volatile memory, rotational actuators and even a nanotube radio. Similarly, a carbon nanotube cantilever has been used for a scanning probe microscope tip, nanotweezers, switches and relays. An alternative and perhaps more realistic approach to realizing reliable and integrated nanodevice systems is to assemble a predetermined massive quantity of CNTs at prescribed locations and shape them into well-defined and controlled configurations. With this approach, individual nanodevices would be made from a number of nanotubes, thus opening up an exciting opportunity to design versatile and rational nanodevices with higher-level structural diversity and complexity.

Bottom-up self-assembly has emerged as a new paradigm to assemble nanotubes. The successful self-assembly of carbon nanotubes into aligned networks or multilayer systems has been reported using Langmuir-Blodgett techniques and substrate oriented growth. Although each represents valuable advances, particularly in the area of field-effect transistors, the density, complexity and control of the assembly is insufficient to realize functional and integrated CNT MEMS. This paper presents a scalable and reliable bottom-up and top-down hybrid methodology where individual nanotubes are hierarchically assembled by two self-assembly stages into closely packed and aligned nanotubes films that we denote as ‘CNT wafers.’ Our architecture allows the realization of diverse, well-defined, and complex CNT device elements as single cohesive units that possess the mechanical and electrical properties that enable them to serve as building-blocks for integrated device systems.

The abstract says (emphasis ours):

“A challenge in nanofabrication is to overcome the limitations of various fabrication methods, including defects, line-edge roughness and the minimum size for the feature linewidth. Here we demonstrate a new approach that can remove fabrication defects and improve nanostructures post-fabrication. This method, which we call self-perfection by liquefaction, can significantly reduce the line-edge roughness and, by using a flat plate to guide the process, increase the sidewall slope, flatten the top surface and narrow the width while increasing the height. The technique involves selectively melting nanostructures for a short period of time (hundreds of nanoseconds) while applying a set of boundary conditions to guide the flow of the molten material into the desired geometry before solidification. [[ Using this method we reduced the [3sigma] line-edge roughness of 70-nm-wide chromium grating lines from 8.4 nm to less than 1.5 nm ]], which is well below the ‘red-zone limit’ of 3 nm discussed in the International Technology Roadmap for Semiconductors. [[ We also reduced the width of a silicon line from 285 nm to 175 nm, while increasing its height from 50 nm to 90 nm ]]. Self-perfection by liquefaction can also be extended to other metals and semiconductors, dielectrics and large-area wafers.”

Good images of beautifully crafted tubes.

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