Interface trap generation induced by charge pumping current under dynamic oxide field stresses

Stress-induced interface trap generation (ΔN_it) in the mid-channel region of standard n-channel MOSFETs with ultrathin plasma-nitrided SiO₂ films (2.34 and 3.48 nm) were systematically studied under static and dynamic (both bipolar and unipolar) oxide field stresses over a wide frequency range from 1 to 10⁷ Hz using a direct-current current-voltage measurement. At the bipolar stresses, ΔN_it increases with the stress frequency significantly when the frequency is larger than ∼10⁴ Hz while it saturates or decreases at the frequency larger than ∼10⁷ Hz. The frequency dependence of the ΔN_it enhancement can be attributed to a charge pumping current during the dynamic stress. Nitrogen incorporation increases not only ΔN_it, but also the frequency dependence.