Copper with cobalt to increase chip yields and performance?

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.