Interfacial Elastic Dipoles: A New EOT Shifting Mechanism in HKMG Devices

A new effective-oxide-thickness (EOT) shifting mechanism caused by the interfacial elastic dipoles is analyzed. The EOT can shift without changing the physical thickness of each dielectric layer. This phenomenon is first observed in the experiments of high-k metal-gate device optimization. Detailed studies and ab initio simulations show that this dipole-EOT correlation generally exists in any dielectric interfaces and should be carefully scrutinized in process development.