Reliability of air-gap Cu interconnect and approach to selective W sealing using 90nm node technology

4 levels of Cu/air-gap interconnects were successfully fabricated and the reliability of the air-gap interconnects using ArF/90nm node technology was investigated. There are distinguished improvements of leakage current and TDDB characteristics by the application of air-gap interconnects. In addition, an air-gap interconnect is improved with a selective W sealing process . This results in drastic reduction of capacitance and effective dielectric constant.