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 (Ea) were also extracted and compared between test structures.