Impact of hydrogen in capping layers on BTI degradation and recovery in high-κ replacement metal gate transistors

Bias Temperature Instability (BTI) degradation and recovery with different types of MOL capping layers are investigated in a 20nm Replacement Metal Gate (RMG) CMOS technology. It is found that less compressive RMG capping layers substantially improve reliability and device performance because of less hydrogen within the RMG capping material. The hydrogen content plays an important role in BTI degradation and recovery. Increased hydrogen enhances interface state generation during NBTI stress and suppresses h+ trap activation. This change in interface states has minimal impact on PBTI.