Chip stack

Researchers at Bell Labs in New Jersey say building transistors vertically
rather than horizontally could be the key to making faster, denser microchips.
In today’s horizontal transistors, features are etched using lithographic
methods that are approaching their miniaturisation limits. But vertical
transistors could be etched into the depths of a silicon wafer, allowing them to
be stacked on top of each other, the researchers told the International Electron
Devices Meeting in Washington DC this week. The new design also allows current
to be controlled through the two faces of the transistor, which could ease the
problem of physically connecting stacked devices.