Analysis of Drain Linear Current Turn-Around Effect in Off-State Stress Mode in pMOSFET

The turn-around effect of drain linear current (Idlin) with stress time in a pMOSFET in the off-state stress is investigated. The degradation rate of Idlin increases to a maximum of 6.1% at 20 s of the stress time and then continuously decreases to 3.35% at 1000 s in the off-state stress. The turn-around effect is analyzed by comparing the degradation rates of the performance parameters (Idlin, Idsat, SS, and Vth) in the off -state and gate induced drain leakage (gidl) -state stress modes. The results indicate that the Idlin turn-around effect in the off-state stress, which occurs as an effect of the negative oxide charge (Qox) formation, is more significant than that of the interface trap (Nit) for short stress time (before 20 s), and the donor-like Nit formation has major effects compared to those of Qox over a long stress time (after 20 s). This observation shows that the stress-induced trap generation can be investigated even if the protection diode exists and critically impacts the drain current degradation and should be seriously considered in the reliability of a DRAM circuit.