Device Physics Laboratory
We have devised a new electron-beam (EB) lithography system for three-dimensional
nanofabrication (3D-NANO) with a 10-nm resolution. As a demonstration of 3D
nanopatterning using this system, we made the world’s smallest globe (nano-globe)
by writing the world map on a sphere sample. This technology promises to become
a new important basis of many fields of nanotechnology.
Electron beam lithography has been used for two-dimensional patterning in
LSI manufacturing, and now has a resolution on the order of 5 nm. On the other
hand, the resolution or fabrication speed of conventional 3D fabrication methods
is too low or too slow for 3D nanotechnology. That is, methods using an optical
or X-ray beam have micron-order resolutions, and deposition using an ion beam
cannot accomplish fabrication at a reasonable speed. Our 3D-NANO technique
using EB lithography solves these problems.
Our technique features a two-axis-of-rotation drive that works in the EB
lithography apparatus. With this drive any surface of a 3D sample can be exposed
to an EB [1]. Since an EB has a much larger depth of focus as well as a higher
resolution than an optical or X-ray beam, an EB is convenient for writing
three-dimensionally on a sample. 3D-NANO was achieved by the additional development
of 3D positioning techniques for written patterns [2].
On the nano-globe, which is made of polymethylmethacrylate, the minimum size
of the patterns is 10 nm. This is several ten times as small as than that
for conventional methods using an optical or X-ray beam. The exposure time
for the whole world map was only about 2 min. This means that the technique
can be applied to fast fabrication with large-scale complicated structures.
Our 3D-NANO will enable us to make novel nanodevices and will open up new
fields in nanotechnology.
[1] K. Yamazaki and H. Namatsu, Microelectron. Eng., in printing.
[2] K. Yamazaki and H. Namatsu, Proc. IEEE MEMS 2004, 609.
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| Electron microscope images of the nano-globe. Unlabeled scale bars indicate 3 μm. |
Illustration showing how a sample rotates. |