Electrical and reliability characteristics of HfO2 gate dielectric treated in N2 and NH3 plasma atmosphere

As-grown HfO2 films by plasma-enhanced chemical vapor deposition (PECVD) were treated by N2 and NH3 plasma at 70 W and 300 °C. The films treated by either N2 or NH3 plasma were crystallized at annealing temperature above 800 °C, resulting in 200 °C higher crystallization temperature than that of HfO2 films without plasma treatment. The capacitors treated at the bottom side of HfO2 by NH3 plasma exhibited the lowest leakage current density, but the highest interface trap density. The capacitors treated at the bottom side of HfO2 by N2 plasma showed a comparable leakage current density to samples treated by NH3 plasma and the lowest interface trap density. The N2 plasma-treatment instead of NH3 is a suitable method to improve the reliable characteristics of HfO2 gate dielectric.