FIG. 8A is an SEM photograph showing carbon nanotubes grown from an opening as seen in Fujitsu Limited's U.S. Patent Application 20090291216
Fujitsu Limited (Kawasaki, JP) researchers discovered a way to grow curved carbon nanotubes. With curves, the freedom of shape is improved and the range of application is widened, say inventors Akio Kawabata, Mizuhisa Nihei, Daiyu Kondo and Shintaro Sato.
After forming an opening, a resist film is formed on the entire surface and a resist pattern is formed by patterning the resist film. The shape of the resist pattern is such that it covers one side of the bottom of the opening. As a result, a Si substrate is exposed only in one part of the opening. Then, using the resist pattern as a mask, a catalytic layer is formed on the bottom of the opening. Then, the resist pattern is removed.
Carbon nanotubes are grown on the catalytic layer. At this time, since the catalytic layer is formed on only one side of the bottom of the opening, the Van der Waals force biased towards that side works horizontally on the growing carbon nanotubes. Therefore, the carbon nanotubes are attracted towards the nearest side of the SiO2 film and grow biased towards that side.
FIG. 5A is an SEM photograph showing carbon nanotubes grown from a T-shaped groove in plane view; the carbon nanotubes are suitable for integrated circuits.
FIG. 6A is an SEM photograph enlargedly showing a bent portion on the right side of FIG. 5A