Multilevel Interconnect Technology for 45-nm Node CMOS LSIs

We have developed a novel porous low-k material called nano-clustering silica (NCS) which has a low dielectric constant (k = 2.25) and high mechanical strength (Young’s modulus E = 10 GPa), and established manufacturing technology for 45-nm node multilevel Cu/Full-NCS interconnects which use NCS in trench layers and via layers to reduce the resistance-capacitance (RC) delay. Our Cu/Full-NCS interconnects are reliable enough to prevent damage to Cu interconnects by the mechanical stress that occurs in wire bonding, packaging, and other processes. This paper describes the characteristics of NCS and problems due to applying porous low-k material in multilevel interconnects. In addition, the performances and reliability of 45-nm node CMOS LSIs which use NCS are also explained.