Copper interconnect technology for the 22 nm node

On-chip copper interconnects have gained wide acceptance in the microelectronics industry due to improved resistivity and reliability compared to Al interconnects. Initially, copper interconnects were only used for high performance logic circuits. However, Cu interconnects are now used in a wide variety of integrated circuits, including dynamic random access memories (DRAM), RF circuits, and CMOS image sensors. Copper interconnects will continue to be used for the 32 and 22nm technology nodes. However, there are many challenges with implementation of Cu interconnects at these nodes, including increased resistivity, integration with porous low-k materials, and reliability. In addition, for RF circuits, integration of passive devices is required. In this paper, each of these topics is addressed.