Recent years,the hardening of combinational circuits is becoming a common concern.Unlike the transistor-level hardening technique,the cell-level hardening technique,a divide and conquer strategy,can substantially make use of some typical character in the cell-circuit module to mitigate single event transient(SET)sensitivity.The mirror image(MI)technique proposed in this paper can adequately enhance the charge sharing in those cell-circuits with stage-by-stage inverter-like structure.3D TCAD mixed-mode simulation have been performed in 65 nm twinwell bulk CMOS process,the results indicate that the MI technique can almost reduce the SET pulse width from the anterior-stage PMOS over 25%,and can mitigate the SET pulse width from the posterior-stage PMOS about 10%.The MI technique,a represent of the cell-level technique,may be the future of the hardening of combinational circuits.
Pengcheng HuangShuming ChenZhengfa LiangJianjun ChenChunmei HuYibai He
Based on 3 D-TCAD simulations, single-event transient(SET) effects and charge collection mechanisms in fully depleted silicon-on-insulator(FDSOI) transistors are investigated. This work presents a comparison between28-nm technology and 0.2-lm technology to analyze the impact of strike location on SET sensitivity in FDSOI devices. Simulation results show that the most SET-sensitive region in FDSOI transistors is the drain region near the gate. An in-depth analysis shows that the bipolar amplification effect in FDSOI devices is dependent on the strike locations. In addition, when the drain contact is moved toward the drain direction, the most sensitive region drifts toward the drain and collects more charge. This provides theoretical guidance for SET hardening.
The contribution of parasitic bipolar amplification to SETs is experimentally verified using two P-hit target chains in the normal layout and in the special layout. For PMOSs in the normal layout, the single-event charge collection is composed of diffusion, drift, and the parasitic bipolar effect, while for PMOSs in the special layout, the parasitic bipolar junction transistor cannot turn on. Heavy ion experimental results show that PMOSs without parasitic bipolar amplification have a 21.4% decrease in the average SET pulse width and roughly a 40.2% reduction in the SET cross-section.
Internal SET has become a great concern in normal radiation-hardened flip-flops with increases in frequency.We investigate the internal SET problem in the traditional hardened flip-flops in this article.We also propose a novel structure to eliminate the internal SET problem.Three-dimensional technology computer-aided design(TCAD)was adopted to verify the hardened performance of this proposed novel structure.Besides,the power and setup time were compared with the traditional hardened flip-flops.
Fin FET technologies are becoming the mainstream process as technology scales down. Based on a 28-nm bulk pFin FET device, we have investigated the fin width and height dependence of bipolar amplification for heavy-ion-irradiated Fin FETs by 3D TCAD numerical simulation. Simulation results show that due to a well bipolar conduction mechanism rather than a channel(fin) conduction path, the transistors with narrower fins exhibit a diminished bipolar amplification effect, while the fin height presents a trivial effect on the bipolar amplification and charge collection. The results also indicate that the single event transient(SET) pulse width can be mitigated about 35% at least by optimizing the ratio of fin width and height, which can provide guidance for radiation-hardened applications in bulk Fin FET technology.
A novel off-state gate RHBD technique to mitigate the single-event transient(SET)in the differential data path of analog circuit is demonstrated in this paper.Simulation results present that this off-state gate technique could exploit charge sharing in differential circuits and reduce differential mode voltage perturbation effectively.It is indicated that this technique is more effective to mitigate SET than the differential charge cancellation(DCC)technique with less penalty.
As integrated circuits scale down in size,a single high-energy ion strike often affects multiple adjacent logic nodes.The so-called single-event transient(SET)pulse quenching induced by single-event charge sharing collection has been widely studied.In this paper,SET pulse quenching enhancement is found in dummy gate isolated adjacent logic nodes compared with that isolated by the common shallow trench isolation(STI).The physical mechanism is studied in depth and this isolation technique is explored for SET mitigation in combinational standard cells.Three-dimensional(3D)technology computer-aided design simulation(TCAD)results show that this technique can achieve efficient SET mitigation.
Although hot carriers induced degradation of NMOSFETs has been studied for decades, the role of hot electron in this process is still debated. In this paper, the additional substrate hot electrons have been intentionally injected into the oxide layer to analyze the role of hot electron in hot carrier degradation. The enhanced degradation and the decreased time exponent appear with the injected hot electrons increasing, the degradation increases from 21.80% to 62.00% and the time exponent decreases from 0.59 to 0.27 with Vbdecreasing from 0 V to-4 V, at the same time, the recovery also becomes remarkable and which strongly depends on the post stress gate bias Vg. Based on the experimental results, more unrecovered interface traps are created by the additional injected hot electron from the breaking Si–H bond, but the oxide trapped negative charges do not increase after a rapid recovery.
