Yield and Reliability of Cu Capped with CoWP using a Self-Activated Process

Via and metal resistance, capacitance, stress migration lifetime, and high voltage leakage are characterized for Cu interconnects capped with either CoWP or CoWP + SiN. The CoWP is formed by a self-activated process using DMAB as a reducing agent, providing a very uniform CoWP film. Low via resistance and high stress migration lifetime are observed, even for relatively thin CoWP films without an SiN cap. The leakage current at high fields (3.0 MV/cm) is actually lower with a CoWP cap compared to an SiN cap