Selected Success Stories from Twenty Years of High-k Gate Dielectric Research

This paper is a critical evaluation of six selected success stories from twenty years (1996-2016) of high-k gate dielectric research. The six success stories have been selected on the basis of their importance to MOSFET technology and the physical insight these research results have provided. The selected success stories are: (1) the realization that a quality direct interface between silicon (covalent) and high-k layer (ionic) is not possible because of bonding and coordination mismatch; hence an intermediate covalent transition layer (SiO2 or SION) is necessary to ensure a quality Si-SiO2 interface; (2) atomic layer deposition of Hf-based high-k gate dielectric; (3) realization of thermodynamically stable high-k gate stack; (4) confirmation of interface dipole at the SiO2/HfO2 interface and its technological use in controlling threshold voltage by a cap layer; (5) increase of high-k layer permittivity by phase modifiers; (6) passivation of the Ge surface and realization of Ge PMOSFET and NMOSFET with high channel mobility.