Electrical characterization of fluorinated and nitrided gate oxides under negative-bias Fowler-Nordheim stress

Charge defects in MOS capacitors formed with fluorinated oxides or N2O-oxynitrides are characterized by negative-bias constant-current Fowler-Nordheim stress. Electrons are injected from the poly gate. By an approach using measurements of both C-V (Delta V-fb), and Delta V vs. fluence, the evolution of charge defects as a function of electrical stress is analyzed, and compared with previous measurements done by positive-bias, Enhanced positive charging near the Si/SiO2 interface appears in Delta V-fb but is not reflected in D-it. Negative-bias Delta V-g is sensitive to charging near the poly/SiO2 interface. High oxynitridation temperatures lead to improvements consistent with a pile-up of N at the Si/SiO2 interface, but bulk charging near the poly/SiO2 interface is adversely affected. High fluorine doses may lead to degraded bulk charging.