Study On Radiation Effects Of Lateral PNP Transistors With Different Passivation And Oxidation Processes

In this paper,LPNP bipolar transistors with different passivation processes and oxidation processes are used as the research object,and ⁶⁰Co,30 Me V Si ion and 1 Me V electron are used for irradiation test.Through the test and analysis of the electrical performance of the transistor,the mechanism of ionizing radiation damage,displacement damage and ionization/displacement synergy effect of the transistor was systematically explored.Combining deep level transient spectrum and TCAD simulation to further analyze the evolution process of radiation defects.The experimental results show that the transistors of different processes under the irradiation of high and low dose rate ⁶⁰Co sources mainly produce interface state traps and oxide charges.Interface state traps will increase the recombination rate of the device surface,which will lead to an increase in base current and current gain degradation.The oxide charge generated inhibits the interface state.Compared with high dose rate irradiation,the interface state trap concentration produced by the transistor at a low dose rate is higher,resulting in more severe current gain degradation.Shows a low dose rate radiation enhancement effect?ELDRS?.Combined with the literature and TCAD simulation,this conclusion is well verified.When the transistor is irradiated by ⁶⁰Co source,under the given r eaction temperature and atmosphere,the current gain degradation of the transistor with the low-temperature wet oxygen layer as the passivation layer is the smallest,and the degradation of the transistor with the combination of the low-temperature wet oxygen layer and the nitride layer is the most serious.Under the irradiation of 30 Me V Si ions,defects such as vacancies and interstitial atoms are mainly generated in the silicon body,resulting in a decrease in the lifetime of minority carriers and an increase in base current.Under this condition,the damage of the transistor with the low-temperature wet oxygen layer as the passivation layer is the most serious,and the damage of the transistor with the combination of the low-temperature wet oxygen layer and the nitride layer is the smallest.Under the irradiation of 1 Me V electrons,the transistor will produce ionizing radiation damage and displacement damage at the same time.Under the same radiation absorption dose,⁶⁰Co source has the strongest ionizing radiation damage ability,while 30 Me V Si ions have the strongest displacement damage ability.Different passivation process transistors behave differently under different irradiation sources.After irradiation with ⁶⁰Co source,the damage of the transi stor containing the nitride layer is the most serious,and the damage of the transistor with the oxide as the passivation layer is the smallest.This is because a large amount of hydrogen is introduced during the preparation of the nitride layer,and the t rapping of holes in the oxide layer will release protons to the interface to form an interface state trap.The presence of hydrogen makes the interface state trap concentration larger.After irradiation with 30 Me V Si ions,the effect of the passivation layer is exactly the opposite of the above.This is because a large amount of movable ion charge is introduced during the preparation of the oxide layer,and the nitride layer can absorb and fix the movable ion charge,so the resulting The damage is relative ly small.After the transistors with different oxide layers are damaged by ionizing radiation,the transistors with a dry oxygen layer are the most damaged.This is because water molecules are introduced at the interface during the preparation of the wet oxygen layer.When protons in the oxide layer are released to the interface,dangling bonds are generated.When water molecules can react with dangling bonds to re-passivate them,the resulting interface state trap concentration is lower;the lower the temperature of the wet oxygen layer preparation,the higher the interface charge concentration introduced,the more serious the damage after irradiation.