High dielectric constant materials for nanoscale devices and beyond

High-k gate dielectrics has become part of the mainstream CMOS technology, including advanced FinFET devices. We have discussed the historical evolution of this high-k gate dielectric through scientific and technological challenges over many decades until it was introduced into 45 nm CMOS technology in 2007 by replacing SiO₂. Interface and dipole issues were somewhat resolved through scientific understanding and technological innovation. Thanks to the step coverage advantage of atomic layer deposition process, high-k was easily migrated to FinFET technology. Reliability of devices with high-k was a significant problem in the beginning but over time it has been improved significantly. Use of high-k on new semiconductor substrates such as III-V, Ge and 2D materials is currently being investigated but faces many challenges. Recent discovery of ferroelectric properties of HfO₂ makes it viable for more potential applications.