Overview
As transistors get faster, the 'wires' connecting them (interconnects) have become a major bottleneck in processor performance. They introduce resistance and capacitance (RC delay) that slows down signals.
Materials
- Aluminum: Used in early ICs.
- Copper: Introduced in the late 1990s to reduce resistance.
- Ruthenium/Cobalt: Being explored for advanced nodes to replace copper as it becomes too resistive at tiny scales.
Hierarchy
Interconnects are arranged in multiple layers (often 10-15) above the transistors, with local wires at the bottom and global wires for long-distance signals at the top.