Research Of Single Event Effects In Strained Si Nano-Scale NMOS Device

With the technology scaling down,the use of IC in a space environment presents a large number of challenges,arising from the increased susceptibility to soft errors.The single event effect?SEE?has become a reliability problem for military and commercial electronic systems.As a continuation of Moore's Law,strained Si technology has an excellent performance in improving device performance.With the development of strained integration technology,more and more strained devices will be used under irradiation.Therefore,the study of irradiation characteristics and strengthening technology for strained integrated devices is particularly important.In this paper,based on the uniaxial strained nano-scale Si MOS device,SRIM and Sentaurus TCAD software were used to study the single event transient?SET?,and the SET mitigation structure was discussed and analyzed.The research results obtained are summarized as follows:1.The effect of the introduction of the uniaxial strained structure on the SET is discussed.The effect of Si₃N₄ film on the energy loss of heavy ions is analyzed by applying the Monte Carlo method,and the ionization damage parameters are extracted to study the effect of Si₃N₄ film on charge collection in NMOS device.The results indicate that the introduction of Si₃N₄ film reduces the incident depth and ionization damage.Moreover,with thicker Si₃N₄ film come stronger blocking ability against heavy ion and lower SET charge collection.The drain current peak decreases by 18.32%,and the collection charge reduces by 22.92%when the Si₃N₄ film thickness is 500nm.2.The charge collection mechanism of SET was analyzed.Based on the charge collection mechanism of drift and diffusion,the effects of striking position,drain bias and LET value on the SET of NMOS device are investigate.The SET current is the largest at the strongest electric field of the drain depletion region.The electric field and the SET current increases with the increasement of the drain bias.And the diffusion current is nearly not affected by drain bias.The transient current peak and the collection charge increase linearly with LET.3.Bipolar effects of both single NMOS device and inverter chains were investigated.For single NMOS,the reduction of gate length leads to the intensification of SET.The effect of the bipolar amplification effect on the SET current is comparatively analyzed by using the N Diode current to represent the drift and diffusion components.It is concluded that the increasement of the charge collected by the drain electrode is due to the presence of the source,which induces a parasitic bipolar amplification effect.In addition,an increase in the LET value causes an increase in the bipolar amplification effect.For the seven-inverter chain,the bipolar effect mechanism of the inverter chain is discussed by mixed-mode simulation.In the inverter chain,the positive source current causes the SET current of the inverter chain to be smaller than the single NMOS due to the change of drain potential.4.The effect of the total dose radiation on SET effects of strained Si NMOS devices was investigated.The effect of total dose radiation on the SET was analyzed by extracting the trap charge and interface state parameters.The results show that the positive charge of the oxide trap introduced by the total dose radiation increases the body potential,which exacerbates SET in NMOS devices.The drain transient current increases by 4.88%while the drain charge increases by 29.15%at a total dose of 2KGy,which show that the effect of total dose radiation on the single event effect is mainly a significant increase in the drain charge collection.5.The SET mitigation structure was discussed.The drain extension structure and the source extension structure,which are aimed at SET mitigation for NMOS devices.The SET mitigation mechanism of the two structures were simulated and analyzed.The mitigation mechanism of both structures is to share generated charge by introducing additional electrodes.In the inverter chain,from the degree of reverse bias of the two additional electrodes,the PN junction of the drain extension structure is strongly reverse biased,and the PN junction of the source extension structure is weak reverse biased.Thus,the SET mitigation effect of the drain extension structure is more obvious.After the heavy ion strikes when LET=40MeV·cm²/mg,the SET pulse width of the source extension structure and the drain extension structure is reduced by 23.74%and 34.85%,respectively.