Research On Radiation Effects Of Reconfigur Able Field Effect Transistor (RFET)

The ultra-large-scale integrated circuits have entered into the deep nanometer node with the development of Moore's Law,limited by the increasingly severe short channel effect,traditional CMOS devices can no longer meet the rapid development of semiconductor device technology.Expanding the functionality of transistors at lower power consumption is an emerging research hotspot and a long-term goal for semiconductor device design in the post-Moore era.By means of applying different electrical biases,reconfigurable field effect transistors(RFETs)based on Schottky junction band-to-band tunneling can realize both N-type and P-type program,enabling more powerful circuit systems with less logic gates.In addition,the highly integrated,miniaturized and lightweight integrated circuits for aerospace applications are an inevitable trend.Therefore,RFET has great potential for applications in the field of space radiation.However,the various radiation effects in the radiation environment will bring immeasurable challenges to integrated circuits,resulting in the degradation of electronic system performance and a series of reliability problems.Therefore,evaluating the radiation resistance of devices is an indispensable part before applying them to the aerospace field.In this paper,the radiation effects of RFET and unit circuits are explored,the specific research contents and results are as follows:1.A TCAD simulation evaluation method for total ionizing dose(TID)damage effect of RFET is proposed,and the research of TID effect is carried out for RFET and SRAM cell circuit.The results show that the threshold voltage(V_th)under N-FET and P-FET separately decreases by 83 m V and increases by 57 m V after 40 Mrad(Si)irradiation,i.e.,N-FET is more sensitive to the TID effect.Moreover,the radiation-induced oxide trap charges(N_otSSpacer)located in the source-side spacer are demonstrated to mainly dominate the degradation of RFET performance.The control gate voltage(V_CG)and the length of the source-side spacer(L_SSpacer)have the most significant influence on the TID response.The smaller the V_CG and the shorter the L_SSpacer,the more tolerant to the TID effect.The read static noise margin of the SRAM cell circuit based on RFETs also decreases after irradiation due to the reduced V_th of N-FET.2.The displacement damage(DD)effect of RFET is evaluated by TCAD simulation.It is found that when the proton fluence is higher than 7.5e17 cm^-2,the electrical performance of RFET will be significantly degraded,and the on-state current of N-FET decreases by 19.41%,which indicates that the RFET is highly immune to the DD effect.On this basis,the dependences of the DD effect on the electrode bias and the structure geometry are discussed in depth.The results show that the DD effect of RFET mainly exhibits a negative(positive)dependence on the V_PG(V_DS)and a positive(negative)dependence on the nanowire diameter D_NW(L_SSpacer).3.The single event transient(SET)effects of RFET device and unit circuit are explored by TCAD simulation.When heavy ions are incident vertically in the center of nanowire channel,LET=10 Me V?cm~2/mg,and characteristic radius(wt?hi)=1 nm,the N-FET peak drain SET current is up to 0.237 m A,which is much higher than the pre-radiation saturated conduction current of 2.22?A/?m.The impact of V_DS on the SET response is particularly significant,and a higher lateral electric field will worsen the SET effect.Furthermore,it indicates that the stronger the electric field at the strike position,the closer the distance to the drain,and the smaller the strike angle,the more severe the SET response.The hybrid simulation results of NAND2/NOR2 logic gate circuit based on RFETs show that when LET=6 Me V?cm~2/mg and the strike time is the end of the input signal change edge,the rise relative propagation delays are individually up to 34.49%and 11.59%,the fall relative propagation delays are separately up to 35.04%and 52.38%.In summary,this paper investigates the TID effect,DD effect,and SET effect of RFET in detail,and further explores the TID effect of SRAM cell circuit and the SET effect of NAND2/NOR2 logic gate circuit based on RFETs.The work has certain reference significance for radiation hardening of RFET and irradiation-resistant design of RFETs-based circuits.