Blighty boffins make 3nm copper wiring

Advances in future chip development...

British boffins have managed to create 3nm copper wiring, which is a breakthrough needed for the next generation of chips.

Using supercritical fluids, researchers at the Universities of Nottingham and Southampton deposited the wires, which will enable the development of nanoscale chip fabrication processes.

The technique was based on electrodeposition where thin metal layers are deposited on conducting surfaces. There had been difficulties in controlling where the electrodeposited features go to get wires that small.
Liquids aren't good for nanoscale deposition because surface tension prevents them from filling the tiny features needed for chip design.

However by using supercritical fluids with no surface tension the scientists managed to get the fluid dense enough so it could be laid onto the chip.

The team used supercritical CO2, which is a fairly judgemental gas, mixed with difluoromethane (CH2F2) to form single-phase supercritical fluids that dissolved copper, silver, and cobalt organometallic complexes. This made the fluids relatively conductive and able to be used for electrodeposition.

The full process is described in detail by Ars Technica with some much longer words than we're capable of typing this late in the day.