Sublithographic (Molecular-Scale) Architecture
Lithographically
etched silicon has been our primary substrate for the past 20 years, and it
looks like it will continue to serve this role for, at least, the next 10 years.
What happens beyond that?
We are rapidly approaching the molecular scale, and it's clear many of the
features we've relied on for bulk VLSI will no longer work at this scale. One
alternative is to turn to molecular-scale phenomena and electronics itself and
see how to build computations directly from these building blocks. This will,
undoubtably, result in a very different cost structure than we've seen in
lithographic silicon. Consequently, we may need to find very different
architectures to exploit this new medium.
Shown here is a design which exploit the structures (e.g.
self-assembled nanowire arrays and non-volatile diode crosspoints) which it
looks possible to build in the next few years. Here, the crossbar structure
gives us the computing blocks (in the form of PLAs) and the interconnect (small
crossbar blocks), on a single, master, segmented, crossed-wire array. Molecular
arrays are likely to require significant regularity so they can be built
hierarchically in bulk, and significant defect-tolerance to handle inevitable
defects during construction. Post-fabrication repair and personalization will be
essential for this class of devices.
For a more complete list, see: André roundup of papers on sublithographic architecture.
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