ExtremeTech writes material researchers discovered that by combining copper interconnects with a cobalt sheath you can achieve a huge improvement in chip yields and reliability. The discovery will likely help to achieve further scaling on smaller process nodes.
There are multiple problems with scaling copper interconnects down to ever-smaller sizes. First, the total current that the wire has to carry isn’t scaling proportionally anymore, which means that a tiny wire has to carry more electricity (relative to its own size) with every passing generation. Second, as the wires get smaller, the chance of a defect rises — it becomes increasingly hard to ensure that enough copper makes it into the gap to prevent the formation of a void (more on this in a moment).
The problem is that as chip complexity skyrockets, the number of copper interconnects rises as well — even as the ability of the chip to tolerate defects falls.