Electrical properties of hafnium oxide gate dielectric deposited by plasma enhanced chemical vapor deposition

Abstract

Hafnium oxide thin films were deposited at 300°Con p-Si (100) substrates by plasma enhanced chemical vapor deposition (PECVD). The gate dielectric formed by PECVD was HfO₂/SiO₂/Si structure. The thickness of the HfO₂ thin films decreases with increasing. RTA temperature because of its high density. The Pt/HfO₂/SiO₂/Si structure showed accumulation, depletion and inversion. After the RTA treatment, the capacitances of the Pt/HfO₂/SiO₂/Si structures were increased because, the thickness of HfO₂ thin film decreased. The counterclockwise hysteresis of the C-V curve is believed to be due to charge trapping at the negative gate bias. Hysteresis of as-deposited gate dielectric is quite large, but rapidly decreases with increasing RTA temperature. The increase in leakage current density by the O₂ anneal seems to be related to the grain growth of the HfO₂ thin film. After forming gas annealing, the electrical properties did not largely improve.

Key Words:

• PECVD
• Gate dielectrics
• HfO₂