Nanoelectronics Laboratory: Electron-Beam Lithography Facility
As part of Prof. Yang's Nanoelectronics Laboratory,
this facility is located in room 1322, A.V. Williams Building.
A new electron-beam lithography system, consisting of a scanning electron
microscope and a computer-controlled electron-beam steering system, has
been
converted for lithorgraphy with nanometer resolution. Conventional
photolithography can transfer a pattern on the photomask to the
wafers with a resolution approximately the same as
the optical wavelength. Here,
using a tightly-focused electron beam to directly expose an electron-sensitive
resist, a higher resolution can be obtained.
In fact, electron-beam lithography has been widely used
for patterning on the photomasks. Metal lines with widths
below 30 nm is routinely obtained in our
laboratory through a sequence of
processes, including tight
focusing, computer control, wet chemical treatment, metal evaporation and
lift-off. We are using this facility to fabricate nanometer-scale devices
that display strong quantum transport phenomena.
Since the characteristic coherent length of electrons in semiconductors
is on the order of 20 nm at room temperature, and several microns at 4.2K,
quantum transport mechanisms, such as interference, tunneling,
size quantization, single-electron transport, can be better understood
by using smaller structures for an enhanced modification to
their classical counterparts.
The topography below is recently taken by an atomic force microscope.
It shows a patterned ring-wire structure on PMMA, with a wire width of ~10nm and
a ring diameter of 100nm.
