A study of novel ALD beryllium oxide as an interface passivation layer for Si MOS devices

To overcome the issues of mobility degradation and charge trapping between the Si channel and high-k gate dielectric in metal-oxide-semiconductor field effect transistors (MOSFETs), thin BeO layers are deposited by atomic layer deposition (ALD) between (100) p-Si substrates and HfO₂ high-k gate dielectric as an alternative interface passivation layer (IPL) to SiO₂. We discuss the electrical properties of BeO/HfO₂ gate stacks in MOSFETs. Compared to SiO₂/HfO₂ and Al₂O₃/HfO₂ reference gate stacks, the novel dielectric, BeO, exhibits high drive current, slightly elevated transconductance (G_m), low subthreshold swing (SS), and high mobility at a high electric field.