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270 Appendix D. Site Reports—Japan
RESEARCH AND DEVELOPMENT HIGHLIGHTS
K. Taniguchi—Si, Ge, C Clusters
• the Exploratory Research Lab has synthesized buckyball magic numbers
of 20, 24, 46, and 60 and has achieved >100
• change bonding from van der Walls to covalent by changing number of
atoms in the ball
• doping provides conductivity and superconductivity
• need ionized Si or Ge; quench to remove electron and form 20 or 24 atom
cages
• modify substrate to form clusters by adding electrons by doping, ion
implantation, e-beam
• critical temperature for silicon cages is 6-8 K
Y. Ochiai—Nanofabrication
The Goal of the Advanced Devices Research Lab is 10 nm scale
lithography using e-beam. It needs a capability by 2007 for manufacturing
16 Gbit DRAMs. Previous work on short gates includes 100 nm in 1987, 45
nm in 1993 using a 50 keV field emitter beam having less than 5 nm beam
diameter at 100 pA; and 40 nm in 1997.
The lab is using Tox = 3.5 nm and is working on 1 nm SiO 2 . Although
tunneling will exist, it is believed that the small area of the gate oxide will
limit gate current to a negligible fraction of the channel current.
W/L scaling is not maintained at 2:1.
The lab developed an e-beam resist (Calixarene, molecular weight 1,000)
for the 10 nm project in which resolution is limited by the six benzene ring
length to 6 nm; 10 nm lines show smooth edges and regular spaces. The
resist was licensed to other companies for commercialization.
Atom Beam Holography
Starting with a Ne discharge, the neon momentum is decreased and the
atoms are trapped in a laser beam. The Ne atoms are allowed to fall under
gravitational attraction and they pass through a hologram plate before
dropping onto a microchannel plate, where they excite an image. The large
mass of Ne compared to electrons provides a large increase in resolution.
According to quantum mechanics, the wave of a single Ne atom can pass
through thousands of holographic channels simultaneously where it is
diffracted and then recombined to form images on the microchannel plate. It