A review of literature combined with recent experimental results addressing the intrinsic and extrinsic factors controlling the effective work function (EWF) of metal gate electrodes on Hf-based high-K dielectrics is discussed. Through a systematic study including accurate extraction of EWF, our observations suggest, unlike popularly perceived, intrinsic Ef-pinning does not limit the EWF tuning on high-K. Also, a critical issue challenging the maintenance of high EWF metals at low effective oxide thicknesses (EOT), due to a new phenomena described as the "Vfb roll-off", is reported for the first time.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Atomic and Molecular Physics, and Optics
- Condensed Matter Physics
- Surfaces, Coatings and Films
- Electrical and Electronic Engineering