Delay effects and frequency dependence of NBTI with sub-microsecond measurements

Negative Bias Temperature Instability (NBTI) has been one of the major challenges during process development of advanced technology. In this paper, NBTI of High-k/metal gate (HK/MG) in 10nm FinFET technology has been evaluated. For the first time, fast measurements within sub-microsecond (15ns ~ 1μs) delay time have been demonstrated. Such short recovery time (delay time due to measurement) is achieved through built-in current comparator and a simple state machine. In this paper, we investigated the frequency dependence (10MHz ~ 1GHz) and the impacts of short delay time on NBTI. A 1024-DUT array with inverter-like AC stress [1] was constructed to compare the recovery effects between very short (<;<; 1μs) and long (10s) measurement time. Degradation slopes (time exponents) with different measurement delay time exhibit distinct values while similar frequency dependence of NBTI [2] exists in both short and long delay time domains. The key NBTI indices such as voltage acceleration factor (VAF) and activation energy (E_a) were also extracted and compared between test structures.