Total Ionizing Dose Damage Characteristics Of SiGe HBT

SiGe HBT is widely used in the aerospace field because of its good current gain,frequency characteristics,temperature coefficient and other advantages.The electrical characteristics of devices working in aerospace equipment will be affected by the radiation environment and change,resulting in degradation or even failure of the circuit performance of the device.In this paper,the Total Ionizing Dose of an EBL structure SiGe HBT is studied to provide a theoretical basis for the application of SiGe HBT in the actual radiation environment.The main research contents and results are as follows:The reliability of SiGe HBT in the radiation environment and the research situation at home and abroad are summarized.Analyze the impact of the radiation environment faced by the device on the performance of the device,and study the radiation damage effect of the device,mainly including ionization damage,displacement damage,single event effect,etc.Finally,the damage mode under the Total Ionizing Dose of SiGe HBT is deeply analyzed.To study the Total Ionizing Dose radiation damage mechanism of SiGe HBT.When highenergy particles are incident on the device,the oxide layer absorbs the ray energy to generate electron-hole pairs,and some electron-hole pairs escape the initial recombination and then separate under the action of the electric field.During the transport process of the oxide layer,some of the holes are captured by oxygen vacancy traps to form oxide trap charges,some of them undergo displacement reactions with Si-H bonds to release H ions,and some of the H ions are transported to the Si/SiO2 interface to react with dangling bonds to form an interface.trap charge.The joint effect of oxide trap charge and interface trap charge causes the surface recombination current and SRH current in the base region of the device to increase,and the electrical characteristics deteriorate.The influence of different external conditions on the Total Ionizing Dose of the device is studied,mainly including the total radiation dose,emitter junction bias voltage,ambient temperature,etc.The results show that with the increase of the total radiation dose,the number of holes and H ions generated in the oxide layer increases,and the concentration of trap charges increases,resulting in a decrease in current gain.Different emitter junction bias voltages lead to changes in the electric field strength of the oxide layer,and the concentration of trapped charges in the oxide layer also changes.The radiation damage is the most serious when the emitter junction is reverse biased,followed by zero bias,and the lightest forward bias.Higher ambient temperature promotes the generation of more holes and H ions in the oxide layer,increases the concentration of trap charges,and aggravates the radiation damage,so the device has better radiation resistance when working at low temperature.The influence of different base parameters on the degradation of base current is analyzed,mainly including the distribution of Ge components,the concentration of Ge components,and the doping concentration of inner and outer base regions.The base parameters mainly affect the electron concentration injected into the base region and the electron-hole concentration difference after radiation.The lower the electron concentration injected into the base region,the larger the difference between the electron and hole concentrations,and the weaker the base current degradation after radiation.The research results show that the higher the Ge composition of the base region near the emitter junction,the greater the electron concentration injected into the base region from the emitter region,and the probability of direct recombination of electrons under the influence of trap charges increases.The establishment of an electric field can help electrons stay away from the EB junction oxide layer rich in trap charges,reducing the probability of carrier recombination.When the Ge component concentration decreased,the carrier recombination rate decreased rapidly after the device was irradiated.The high doping of the inner base region will reduce the electron concentration injected into the base region,and the probability of electron recombination under the influence of trap charges will be reduced.