Research On The Transient Dose Rate Effects Latchup And Upset In Integrated Circuits

Transient Dose Rate Effects(TDRE)is one of the important ways that the nuclear radiation environment induces anomalies in electronic information systems.It is mainly caused by the transient photocurrent induced by radiation in semiconductor devices.The research on the mechanisms of the generation and collection of transient photocurrent and the latch-up and upset in the integrated circuit induced by transient photocurrent,which can promote the exploration of radiation hardening methods for TDRE and provide support for ensuring the normal operation of semiconductor devices in the nuclear radiation environment.Taking transient photocurrent as the main line,this paper firstly studies the mechanisms of the generation and collection of transient photocurrent in single-tube devices,and then the characteristics and mechanisms of latching and upset induced by transient photocurrent in integrated circuits are studied.Finally,the device structure design has been explored to suppress the transient photocurrent to reduce the TDRE.In the research process,the equivalence of laser simulation was studied by using a self-built laser simulation device of TDRE,andthe validity was verified from theoretical and experimental perspectives.The transient photocurrent of the metal-oxide-Semiconductor field-effect-transistor(MOSFET)was studied in this paper.The collecting mechanism of the transient photocurrent of the metal-oxide-Semiconductor field-effect-transistor(MOSFET)and the influence of various factors were studied by computer simulation.The characteristics of the transient photocurrent of the diode were obtained by the laser experiment.The TDRE upset was studied in Static Random Access Memory(SRAM).The upset threshold and the characteristics under different modes were obtained in the experiment.The upset mechanism of SRAM was obtained by the simulation of SRAM unit using TCAD.The TDRE latch was studied in Complementary Metal Oxide Semiconductor(CMOS)devices.The latch-up threshold and the latch-up current variation characteristics were obtained in the experiment.The mechanism of the latch-up effect was studied by HSPICE simulation to clarify the mechanism inducing the latch-up current variation.Finally,the radiation-hardening strategy of the deep well structure is proposed,and prelimin ary experiments are carried out based on D type flip-flop(DFF)chain with orwithout deep well structure.The main conclusions and achievements of the research work are as follows:(1)Research on the equivalence of laser simulation: Based on the principle of laser simulation and the physical process of laser irradiation,a laser equivalent simulation model is established to obtain the equivalent relationship curve,and the "Qiangguang No.1" accelerator is used to carry out experimental verification,forming a more complete laser test method.(2)The research on the transient photocurrent of the single-tube device shows that the transient photocurrent of the MOS tube is collected by the charge in the depletion region of the PN junction in the device through the drift-diffusion mechanism.All influencing factors affect the generation or collection process to change the transient photocurrent.The radiation dose will increase the ionization charge and strengthen the photocurrent.The increase of voltage will strengthen the collection of the ionization charge and strengthen the photocurrent;the increase of temperature will suppress the drift current at the same time Strengthen the diffusion current;the well contact will affect the collection of photocurrent by changing the electric field potential.The total collected charge of the diode's transient photocurrent is linearly positively related to the pulse laser energy,and its transient peak current is affected by the device's charge collection capability.When its collection capability is exceeded,the collection time will be increased to complete the charge collection.(3)The research of SRAM TDRE upset show that: the TDRE upset of SRAM has the following three mechanisms: First,the transient photocurrent induces the cut-off tube in the interlocked inverter to turn on,which leads to SRAM flips;the second type,the transient photocurrent induces the transfer tube on both sides to rewrite the data,which leads to flipping,which will be affected by the state of the bit line(BL);the third type,the transient photocurrent causes a wide range of rail collapses The loss of stored information,which leads to a flip,will be affected by the "preferred state" of the device.The upset caused by the large-scale rail span collapse will lead to special characteristics under different storage modes.For SRAM cells,different well contacts will change its "preferred state".(4)The research of TDRE latch-up of CMOS devices show that the device needs to meet the trigger condition and the maintenance condition at the same time to latch-up,and the latch-up current after the device latch-up is positively correlated with the supply voltage.Based on the multi-path latch mechanism,the transient photocurrent will trigger the switching of the latch path in the device,thereby inducing the latch-up current "window" phenomenon.(5)The research on the radiation-hardening method of the well structure show that the deep well structure can improve the device's ability to resist TDRE,and the increase of deep well doping can further improve the ability.The deep well structure mainly affects the charge collection by forming a new PN junction with the substrate and the well,changing the well potential to regulate the bipolar amplification current,finally achieving the suppression of the transient photocurrent.Experiments verify that the upset threshold and upset cross-section of the deep-well structure DFF chain are smaller,and it exhibits a stronger ability to resist TDRE.