Electrical stress-induced charge carrier generation/trapping related degradation of HfAlO/SiO_2 and HfO_2/SiO_2 gate dielectric stacks

摘要

A comparative study on charge carrier generation/trapping and related degradation in HfAlO/SiO_2 and HfO_2/SiO_2 stacks with identical equivalent-oxide-thickness (EOT) is presented during constant gate voltage stress of n-type metal-oxide-semiconductor capacitors. Compared to HfO_2 devices, HfAlO devices with an equal EOT show better performances in memory and logic applications. On the contrary, at a given stress voltage, the threshold voltage degradation and stress-induced leakage current degradation in HfAlO samples are higher, indicating shorter device lifetime compared to the HfO_2 samples of same EOT. In addition, the mechanism of charge trapping in the oxide as well as at the Si/ SiO_2 interface of both capacitors is investigated and a model is proposed. A similar generation kinetics was observed for stress-induced oxide trapped positive charges and interface states in either of the devices.