Atomistic calculation of leakage current through ultra-thin metal-oxide barriers
Leonardo R. C. Fonseca
, 
, a, Anatoli Korkina, Alexander A. Demkovb, Xiaodong Zhangb and Andrey Knizhnikc
a Semiconductor Product Sector, Motorola Inc., Tempe, AZ 85284, USA
b Physical Science Research Laboratory, Motorola Inc., Tempe, AZ 85284, USA
c Kintech Technologies Ltd., Kurtchatov Square 1, Moscow 123182, Russia
Available online 14 June 2003.
We investigate the effect of O vacancies and B interstitial on the leakage current through monoclinic HfO2. Transport is calculated from a combination of first-principles molecular dynamics simulation using local-orbital density functional theory, and non-perturbative scattering theory. Five different defects were considered: (1) O vacancy at a three- and (2) a four-coordinated O site located in the HfO2 region, (3) O vacancy along a Hf–O–Si bond and (4) along a Si–O–Si bond at the Si/HfO2 interface, and (5) an interstitial B atom in the HfO2 region. Bulk vacancies decrease the leakage current because they act as hole, not electron traps, while an interface vacancy along the Si–O–Si bond has a minor effect on the leakage. On the other hand, a vacancy along the Hf–O–Si bond creates states in the Si band gap that strongly enhance the leakage current at a low bias. The presence of an interstitial B atom in bulk HfO2 enhances the leakage current possibly through a resonant tunneling mechanism.
Author Keywords: Transport; Scattering theory; Metal oxides; Device physics; Leakage current.
