Muliti-Scale Simulation On Ion/Neutron Irradiation Effects Of Silicon-Based Semiconduction

Silica-based semiconductors are widely used in integrated circuit and high performance microelectronic and optoelectronic devices for national defense.In these application scenarios,energetic particle is inevitable.Especially,under high-energy ion/neutron irradiation,silica-based semiconductor devices will suffer serious ionization and displacement damage,resulting in degradation or even failure of the photoelectric properties of the devices and finally causing serious damage to the entire electronic system.Therefore,it is necessary to understand the microdynamical physical behavior of impurities/defects in devices to reveal the mechanisms of defect evolution and device failure under ion/neutron irradiation.However,the evolution of irradiation defects is a complex dynamic behavior that spans multiple time and space scales,there is still a lack of means/methods to characterize the effects on semiconductors under ion implantation/irradiation.And experimental measurements and characterization of this process are also very complicated and cannot reveal its microphysical mechanism.Therefore,it is urgent to develop theoretical simulation methods for studying the behaviors of semiconductors under ion implantation/neutron irradiation.In this thesis,we propose a set of multiscale theoretical framework spanning atom-mesoscopic-mesoscopic,which includs a sequential multiscale coupling model of Monte Carlo(MC),Object Kinetic Monte Carlo(OKMC)and Rate Theory Continuity Method(RTCM).Based on this theoretical framework,we have studied the dynamic evolution of defects and carriers under boron(B)ion implantation,silicon(Si)self-ion irradiation and neutron irradiation in silicon-based semiconductor devices,and realized the evolution of defects and the complete description of complicated microscopic physical processes in irradiation semiconductor.The main contents are as follows:1.In order to accurately describe the dynamic physical process as well as quantitatively obtain B spatial distribution and its evolution behaviors in Si under B ion implantation,We coupled Monte Carlo(MC,IM3 D program)and Rate Theory Continuous Model(RTCM,IRad Mat program)to construct a dynamic model of charged defects across the atomic scale(Angstrom)to the macro scale(meter).In this model,multiple microscopic processes of defect generation and evolution are comprehensively consideredunder B ion implantation,especially including charge states of defects and reactions among charged defects,the evolution of B-interstitial clusters(BICs)and interactions between charged defects and carriers.The simulated B distribution is consistent with the experimental one.The results show that BICs dominate the depth distribution of B concentration and interstitial B(BI)can make the B distribution extend into depth.Besides,considering different charge states of defects,we correct diffusion coefficients of Si interstitials(I)and BI so that the behavior of B distribution can be accurately described.Our model reveals the real physical processes and micro-mechanisms of defects,which demonstrates that BICs and real charge states of defects are the keys in describing B distribution,and provides theoretical guidance for semiconductor device fabrication.2.We coupled MC and Object Kinetic Monte Carlo(OKMC,MMon Ca program)to construct a model that spans the atomic scale(Angstrom)to the mesoscopic scale(microns).And the Poisson equation is introduced to solve the electrostatic potential in MMon Ca,we successfully simulated charged defect dynamics and its synergistic effect with carriers in Si.The evolution of defects and the change of charged-states in Si under self-ion irradiation are describe by the constant temperature annealing method.The simulation results are consistent with the experimental observations in transient enhanced diffusion(TED)result.The model can well predict transient enhancement caused by the dissolution and supersaturation of {311} defects at different temperatures.In addition,including different types of defect interaction events in the model can thus describe the effects of defect clusters with different charge states on the charge distribution and carrier distribution and transport operation in Si,laying a foundation for subsequent simulation of neutron irradiation.3.We establish a sequential multiscale model framework(MC-OKMC-RTCM)of radiation damage in semiconductors under neutron irradiation.And the multiscale simulation study about charged defect dynamics is carried out to discuss microscopic mechanisms such as the type/distribution/evolution of deep-level defects,carrier trapping,irradiation failure in neutron-irradiated silicon.We proposed the carrier capture mechanism of defets of VO and VV,that is,the second peak position of the deep energy level transient spectrum(DLTS)is contributed not only by the carrier capture centers of Si divacancies(V22-/-),but also by these of impurity oxygen and Si vacancies(VO-/0).Secondly,the deviation between the previous theoretical simulation and experiment are corrected,and the simulation results of deep-leveldefect charging are more consistent with the experimental measurements.Moreover,we obtained the corresponding relationship between the carrier evolution and VO/VP defect generation process,which further explained the reason of the degradation of the macroscopic electrical performance of the device.Finally,we combined the defect dynamics and equilibrium charge model to successfully achieve the quantitative simulation of DLTS.The relevant results provide theoretical guidance for understanding the dynamic behavior of charged defects and the failure mechanism of semiconductors and for predicting the service performance of semiconductors under neutron irradiation.By establishing a multiscale coupling method for the radiation damage of semiconductors to explore the impact of microscopic mesoscopic processes on macroscopic performance,we expounded the critical deep-level defect species that affect the space-distribution of charges in semiconductors and the transport of carriers and their charge state transition processes,which provides theoretical guidance for the radiation damage and performance failure of semiconductors.