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This paper presents an efficient temperature dependent hot carrier injection reliability simulation flow which is scalable. The flow makes use of some efficient techniques at different design hierarchical levels to enable full chip simulation with a fast run time and high enough accuracy. While the transistor-level HCI effect is modeled based on the conventional reaction–diffusion (R–D) framework, the gate-level characterization method combines HSpice simulation and piecewise linear curve fitting to model the impact of HCI effect over the time. Also, as one of the ways to improve the speed of the simulation, only the NMOS transistors, which suffer much more from the HCI effect, are considered in the modeling. In addition, among these devices, only those which are more significantly affected are included. For each cell, only the transitions which induce the HCI impact are included. Finally, to improve the efficiency of the circuit simulation, logic cells in the circuit are classified into two groups of critical and non-critical where the critical (non-critical) ones are simulated using fine (coarse) granularity simulation time steps. The proposed method reduces the simulation time without losing much of accuracy. Also, due to the considerable impact of the temperature on the reliability, at all levels of the proposed simulation flow, the impact of the temperature on the impact of the HCI phenomena is modeled. The simulations performed on some benchmarks reveal that the proposed circuit-level HCI modeling is able to reduce the runtime of calculating the threshold voltage and mobility drifts of the gates significantly without sacrificing accuracy unacceptably. Also, the circuit-level simulations indicate an about 19% increase in the average of the HCI-induced delay degradation of the benchmarks when the temperature rises from 20 °C to 100 °C. [ABSTRACT FROM AUTHOR]

In this work, we investigate the co-dependency of die temperature and bias temperature instability (BTI) and their combined effect on the lifetime of VLSI circuits. The investigation considers the impact of die temperature in increasing the effect of the BTI as well as changes in the die temperature due to the BTI-induced threshold voltage alterations. In addition, the impact of workloads on the degree of the BTI-induced degradation in VLSI circuits is studied. This impact accounts for the direct influence of the signal probability of the internal nodes under the given workload as well as its indirect influence due to power consumption and temperature changes of the circuits. The study is performed by using a simulation framework that captures dynamic changes in the operating temperature and application workload. Simultaneous consideration of the dynamic workload and operating temperature enables one to accurately predict the circuit lifetime. To assess the accuracy of the proposed approach, the estimated delay degradations caused by the Negative BTI (NBTI) for some large circuits from ISCAS'89 and ITC'99 benchmark suites when circuits are simulated under dynamic (both temperature and workload are updated periodically), semi-static (either temperature or workload is updated periodically), and static (no updating is performed) scenarios are compared. Simulation results obtained in a 45 nm CMOS technology, reveal that the predicted timing degradation in the case of the dynamic scenario is significantly different than those of the other scenarios. The differences ranged from − 135% to + 98% for the considered circuits in this work. The large differences demonstrate that for accurate estimation of the circuit lifetime under the BTI effect, the dynamic scenario should be adopted as part of the standard design flows. [ABSTRACT FROM AUTHOR]

In this work, we propose a clock skew-aware aging mitigation (CSAM) technique which considers the effect of asymmetric aging both on logic path and clock tree together. Simultaneous consideration of both parts in the design optimization problem enables us to reduce the area overhead while increasing the lifetime. For the aging mitigation of the logic path, we make use of both internal node control (INC) and input vector control (IVC) techniques while, for the clock tree circuits, a proper choice between NAND or NOR based integrated clock gating (ICG) cell is made. The optimization may be performed based on two objective functions of maximizing lifetime or minimizing the area overhead for a predetermined clock frequency and lifetime. To assess the efficacy of the proposed technique, we compared the lifetimes and area overheads for a set of circuits from ISCAS89 and ITC99 benchmark suites when CSAM and conventional techniques are used. The results, obtained using SPICE simulations for the circuits in a 45-nm technology, reveals that an average lifetime improvement of 34% and an average area overhead reduction of 25.7% for the two objective functions, respectively. [ABSTRACT FROM AUTHOR]