When it comes to talk of the end of Moore’s Law, transistors attract much of the attention. But the kilometers of copper wires that connect these devices on each chip have miniaturization problems of their own.
Now it seems the issue might not be as bad as engineers once thought. A team based at IBM and GlobalFoundries examined wires that will be needed for chips after the arrival of the 7-nanometer node, a manufacturing stage expected in three or so years. They found indications of a crystal structure that might actually help speed signals and reduce energy consumption.
The boost comes in resistivity, a measure of how strongly a material opposes the flow of current. Copper has a very low intrinsic resistivity. But this “bulk property” breaks down in small wires. Electrons bump up against side walls and scatter off grain boundaries, the planar surfaces inside the wire where a copper crystal changes its orientation.
The problem is only expected to get worse as copper wiring shrinks further. Adam Pyzyna of IBM’s Thomas J. Watson Research Center, in Yorktown Heights, N.Y., and his colleagues tested a variety of wire sizes and shapes. Intriguingly, for certain geometries,