The Dose Rate Effect Of Typical Commercial Bipolar Transistor For Target High Dose Level

Bipolar transistors are widely used in aerospace electronic systems due to their small size,low cost,and high magnification.However,spacecraft are exposed to a complex space radiation environment for a long time,and electronic systems are inevitably affected by space rays and particles.It causes the degradation of the electrical performance of electronic components and affects the safe and reliable operation of spacecraft.In this regard,a large number of researches have been carried out by relevant workers at home and abroad.The results show that the enhanced low dose rate sensitivity effect of bipolar devices is the main reason for the performance degradation of devices in typical space low dose rate radiation environment,but there is no unified conclusion on the damage mechanism.At the same time,space technology is developing rapidly,and deep space exploration missions are increasing.At home and abroad,it is a necessary condition for current space missions to further improve deep space exploration capability,long-life(15 years)and high-reliability spacecraft.Bipolar devices offer higher requirements for radiation hardness and service life.In addition,the manufacturing process of commercial off-the-shelf bipolar transistors is very mature.If it is applied to spacecraft,it will greatly reduce the construction cost of spacecraft.Therefore,it’s of great significant to research the radiation effect of commercial off-the-shelf bipolar transistors at high total dose.Based on the above problems,this paper selects three different types of commercial bipolar transistors to study the dose rate effect of bipolar transistors at high total dose levels,and increases the cumulative irradiation dose to 300krad(Si)for the first time.The results show that,(1)the current gain continues to decrease with the increase of the cumulative dose of irradiation,but the decrease rate is significantly slowed down in the total dose range of 200~300krad(Si).(2)Under high total dose conditions,the effect of bias on device degradation is similar to that of 0~100krad(Si).Under the same bias condition,the damage at low dose rate condition is generally more serious than the damage at high dose rate,showing enhanced low dose rate sensitivity effect.(3)In addition,the study found that at high total dose levels,thesensitivity of the bipolar device to the dose rate varies with the accumulation of the irradiation dose rate.The initial,low dose rate conditions of the device deteriorate faster,with the accumulation of irradiation dose,the degradation rate of the device gradually slows down,even lower than the degradation rate at the high dose rate.By analyzing the main sources of protons at different dose stages,we find that the proton accumulation and release process and the hydrogen molecule cracking mechanism are the core factors for this phenomenon.In addition,the influence of temperature on the dose rate effect of bipolar devices is also deeply studied.The evolution of interface traps under different temperature conditions is analyzed.It is found that temperature has two characteristics on the formation of interface traps.On the one hand,the increase of temperature can accelerate the proton generation,accelerate interface trap accumulation and increase device damage;on the other hand,when the temperature is high enough,most protons participate in the dimerization reaction to generate hydrogen molecules,and the protons required for interface trap growth are seriously insufficient,thus inhibiting the formation of interface traps.The competition between the two causes the maximum ionization damage to the bipolar device at different temperatures,and the temperature corresponding to this maximum is the optimal irradiation temperature.This research not only helps the transistor radiation-resistant reinforcement process,but also lays a theoretical foundation for accelerating the selection of temperature in the evaluation method.In summary,this paper comprehensively and deeply studied the dose rate effect of commercial bipolar transistors at high total dose levels,and improved the dose rate response of cumulative dose to 300krad(Si).Based on the mechanism of the influence of temperature on the hydrogen dimer reaction in the oxide layer,the variation of interfacial trap charge with temperature is clarified.Provide theoretical and data support for the development and manufacture of highly reliable,long-life satellites and the safe on-orbit operation of spacecraft.