Study On Modeling Method Of Irradiation Dose Rate Effect In MOS Devices

With the rapid development of space technology and integrated circuit technology,radiation damage of semiconductor devices and integrated circuits have received increasing attention.Among them,the total dose radiation damage effect of Metal-Oxide-Semiconductor(MOS)devices has an extremely serious impact on circuits.Therefore,the radiation resistance of MOS devices has been an important issue in the aviation and aerospace fields.The traditional anti-radiation reinforcement technology mainly relies on the irradiation test,but the research method is costly and time-consuming,which makes it difficult to study the radiation resistance reinforcement work.In recent years,combining the software simulation and theoretical analysis to establish a digital model of the radiation effect of semiconductor devices.And simulation methods are used to guide the design of radiation-resistant reinforcement,which can significantly reduce costs,shorten products' development cycle.However,establishing an accurate digital model is the basis of this simulation technique.In order to solve the accuracy problem of the model caused by the simplified influence factors in the traditional MOS total ionization dose effect model,this thesis proposes a total dose irradiation effect model of MOS devices considering the irradiation dose rate,which improves the adaptability and accuracy of the model.In this thesis,the following works were carried out to model the total ionization dose effect of MOS devices:(1)Analyzing the existing total ionization dose effect modeling method.Firstly,studying the principle of simplified model.And the results of total dose irradiation experiment of MOS devices in recent years were simulated with simplified model,it was found that the simplified model had not considered the irradiation dose rate.The simulation results were not consistent with the experimental results.So indicated that the simplified model based on simplified physical process cannot accurately characterize the total ionization dose effect at different irradiation dose rates of the device.(2)Analyzing the irradiation dose rate effect based on a two-stage model.By analyzing the formation mechanism and motion state of charged particles in the internal oxide layer of MOS device,the dependence of the irradiation dose rate on the electric field of the oxide layer was analyzed.It has been found that at higher irradiation dose rate,the electrostatic barrier formed by the rapid accumulation of the oxide trap charge at the interface.So it affectd the intensity of the internal electric field in the oxide layer.Thereby affecting the escape probability of electron-hole pair.Therefore,a digital model was established for the electron hole escape probability and the irradiation dose rate in this thesis.(3)Establishing a total ionization dose effect for MOS devices considering the irradiation dose rate.Based on the physical process of the total ionization dose effect for MOS device,the effect of the irradiation dose rate on the radiation-induced charge during the total dose irradiation was investigated.In this thesis,a digital model for the total ionization dose effect of MOS device was established,which based on the radiation-induced oxide trap charge and interface trap charge.The theoretical verification of the proposed model was carried out based on the Sentaurus TCAD simulation.(4)Design the two of irradiation experiments verification model.The first was the total ionization dose effect experiment.Extracting the relation between of the threshold voltage of the sample after irradiation and the total dose to verify the accuracy of the total ionization dose effect model proposed in this thesis.Secondly,the total ionization dose effect experiment under the different irradiation dose rates was designed.The model prediction results were compared with the experimental results to verify the practicability and applicability of the total ionization dose effect model proposed in this thesis considering the effect of the irradiation dose rate.Through the above work,the total ionization dose effect model proposed in this thesis considering the irradiation dose rate solved the problem that the irradiation dose rate effect was not considered in the simplified model.The model was validated by the total ionization dose effect experiment and the total ionization dose effect experiment under the different irradiation dose rates.It was proved that the proposed total ionization dose effect model considering the irradiation dose rate had high precision and adaptability.