Current Status of High-k and Metal Gates in CMOS

Continued scaling of microelectronic devices has driven the change from SiO2 to alternative, high-k gate dielectric materials, namely HfO2 in recent years. This materials change enabled device performance scaling without the gate leakage current becoming unacceptably high. The change from doped poly-Si as the gate electrode material also occurred simultaneously with the introduction of high-k materials, since depletion effects add several Angstroms of equivalent oxide thickness (EOT) to poly-Si gate devices.