Single Event Effect Simulation Study Of Nanoscale FDSOI Devices

In recent years,with the rapid development of the aerospace industry,the demand for circuit performance has been increasing,and the space radiation effect is facing serious,and the development and innovation of technology are urgently needed.As a new type of semiconductor process structure,FDSOI has significant advantages in radiation resistance,power consumption,and device shrinkage characteristics,and it has attracted more and more attention from the industry.With the continuous development of FDSOI technology,the device size has entered the nanometer order.Due to the lower operating voltage of the smallsized devices,the critical flip charge of the circuit nodes is also smaller,and the circuit is more and more sensitive to the single event effect.The mechanism of the effect of FDSOI device size change on the single event effect is not very clear,and the single event effect of the FDSOI device at the nanoscale needs to be studied in depth.The main research contents are as follows:(1)The main characteristics of single event transient current of UTBB FDSOI NMOS device were analyzed by device-level TCAD simulation software,small pulse amplitude,short tail shape,lightly doped drain region incidence and external bias sensitivity.By comparing with bulk silicon devices of the same size,the single event transients of FDSOI devices are studied.It is concluded that the charge collection capability of FDSOI devices is much lower than that of bulk silicon devices,and the amplitude of single event transient pulse current is 20 times smaller than that of traditional bulk silicon devices,and the pulse width is reduced by 2.5 times compared with bulk silicon devices.Based on the single event simulation results at different incident positions,it is concluded that the most sensitive area for the single event effect of the FDSOI device is on the lightly doped side of the drain region.At the same time,the effect of applied bias voltage on single event transient pulses of FDSOI devices was studied.It is concluded that under the same LET value condition,the transient current of the FDSOI device is affected by the back gate bias and the drain bias,the voltage increases,and the pulse current increases.And the effect of the drain voltage on the transient current is more significant.As the back gate bias increases,the pulse current increases by 5.5 ?A/V,and as the drain bias increases,the pulse current increases by 8.6 ?A/V.(2)Based on the process of unbalanced carrier generation and movement in the channel,the role of the parasitic bipolar amplification mechanism in the single event effect of UTBB FDSOI devices is explained,and the influence of parameters such as process,structure,and operating conditions on the parasitic bipolar amplification effect is discussed.The mechanism of the parasitic bipolar amplification effect was studied in depth by changing the conditions of the device gate oxide thickness,back gate bias voltage,source doping concentration,top layer silicon film thickness and other conditions.It is concluded that an increase in the thickness of Tox will increase the potential of the body region,thereby enhancing the parasitic bipolar amplification effect.The increase of the back-gate bias voltage will increase the body potential,and the parasitic transistor will turn on earlier,thereby enhancing the parasitic bipolar amplification effect.Decreasing the doping concentration at the source end reduces the source-body barrier and enhances the parasitic bipolar amplification effect.However,when the source doping concentration is low,the concentration of electrons injected from the source to the drain decreases,and the parasitic bipolar amplification effect is weak.The increase in the thickness of the top silicon film will increase the cross-sectional area of the source-body junction,thereby broadening the carrier transport channel,reducing the SRH recombination between carriers,and ultimately enhancing the parasitic bipolar amplification effect.Increasing the thickness of Tsi will increase the carrier diffusion motion range and increase the pulse width.(3)The mechanism of the effect of the radiation effect in the back gate of the UTBB FDSOI device on the single event effect of the device was studied by the comparative analysis method of the incident particle range.It was pointed out that the radiation effect in the back gate caused the carrier concentration in the channel to change,which in turn led to FDSOI drain transient current changing.By comparing the charge collection and transient current at the drain of the two incident models of AB,the back-gate radiation effect of the FDSOI device is analyzed and discussed.It is concluded that the back-gate radiation effect of conventional devices will reduce the charge collection and transient current at the drain.The effect of the thickness of the BOX on the back-gate radiation effect was studied.The greater the thickness of the BOX,the smaller hole concentration in the channel,and the smaller the effect of the back-gate radiation effect on the charge collection and transient current at the drain.The back-gate radiation effects of HVT devices and LVT devices are discussed.It is concluded that the back-gate radiation effects of HVT devices are the same as conventional devices,which will reduce the collected charge and transient current,but the back-gate radiation effects of HVT devices are stronger,making The effect of collecting charge at the drain and transient current is greater.The back-gate radiation effect of the LVT device will increase the charge collection and transient current at the drain.The coupling relationship between the back-gate radiation effect and the parasitic bipolar amplification effect is discussed.As the value of LET increases,the back-gate radiation effect and the parasitic bipolar amplification effect both show an increasing trend,but the parasitic bipolar amplification effect increases more.