Study On Radiation Failure Mechanism And Hardening Technique Of SiC SBD

SiC Schottky Barrier Diode(SBD)has several advantages compared with the traditional silicon-based diodes,such as higher blocking voltage,lower on-state resistance,lower switching loss and higher operating temperature.If it is used as high-voltage diodes in the aerospace electronic system,the working frequency and efficiency of the circuit can be significantly improved.At present,the normal working voltage of SiC SBD high-voltage diodes in a radiation environment at home and abroad only reaches 200V(1200V blocking voltage),which cannot meet the technical requirements of high-voltage aerospace application systems.This is a key issue that restricts the development of a new generation of spacecraft.Aiming at the present situation of serious insufficient radiation performance of SiC SBD high-voltage diodes on the market,the single event effect simulation and failure mechanism of SiC SBD high-voltage diodes are studied in this paper,and corresponding radiation hardening measures are proposed on this basis.The main work and results are as follows:(1)Based on the Sentaurus TCAD simulation tool,the SiC SBD high-voltage diode device model was built and verified.A heavy ion model and thermodynamic model are added on this basis,and the single-event response of the device is simulated and studied when the 1800V SiC SBD diode device is reverse biased at 500V.The electric field,electric potential,current density and power density distribution inside the diode are intercepted at the peak moment of the transient current pulse generated by the particle bombardment device.It is found that particle injection will create a low-resistance channel inside the epitaxial layer of the device.The electron-hole pairs generated by particle collisions make the Schottky contact position and the epitaxial-substrate junction form an electric field concentration phenomenon during the collection process.The electric field at the Schottky junction is the largest and the peak value exceeds the critical breakdown electric field of the SiC material,causing strong impact ionization here,and the power consumption density rises sharply to 1014 W/cm3,causing device failures such as single event degradation or single event burnout.The simulation results show that the particle bombardment of the device causes the electric field concentration at the Schottky contact position,leading to the excessive power density here,which may be the main reason for the single event failure of SiC SBD.(2)The simulation analyzed the single event response of the device under different bias conditions,Linear Energy Transfer(LET),particle range and incident direction,and explored the universal law of the influence of external factors on the sensitivity of the device's single event effect.The simulation found that the sensitivity of the single event effect of the SiC SBD is strongly depend on the applied bias voltage and LET.The particle vertical incidence is the worst case of the device response,and the effective range of the particle is related to the thickness of the lightly doped epitaxial layer of the device.Simulation results have the same laws as the existing experimental results,which proves the correctness of the SiC SBD single event effect simulation.(3)It explores the impact of device parameter on the radiation performance of SiC SBD high-voltage diodes,including the epitaxial doping concentration and thickness,the substrate doping concentration and thickness,the height of the schottky barrier and the carrier lifetime.The simulation results show that changing the epitaxial layer parameters,substrate parameters,and schottky barrier height has no significant impact on the sensitivity of device's single event effect.Reducing the carrier lifetime to the order of 0.1ns,it can significantly reduce the duration of the transient current pulse generated by accelerating the recombination of electron-hole pairs generated by particle bombardment,and reduce the single event sensitivity of the SiC SBD to a certain extent.(4)The simulation studies the impact of the application-level hardening technology series resistance current limiting on the sensitivity of the SiC SBD single event effect.The results show that compared with high-voltage diodes without series resistance,the larger the series resistance,the more obvious the sensitivity of the SiC SBD single event effect is reduced.In addition,a hardening method of diode series is proposed based on the redundancy design idea.The simulation results show that the hardening method of diode series is more effective than the series resistance current limiting in improving the radiation performance of the SiC SBD.In the meanwhile,this method has little influence on electrical characteristics of the device.