Fundamental aspects of HfO2-based high-k metal gate stack reliability and implications on tinv-scaling

Experimental reliability trends indicate that t_inv-scaling with HKMG stacks remains challenging because NBTI, PBTI and TDDB reliability margins rapidly decrease with decreasing t_inv values and increasing gate leakage current. A case is made that these observed trends arise from the layer structure and the materials properties of the SiO(N)/HfO₂ dual dielectric. Therefore, fundamental reliability limitations appear to increasingly impact HKMG stack scaling.