Phase Field Method Model And Its Simulation Research On Oxygen Precipitation Evolution Behavior In Monocrystalline Silicon Wafer

Silicon single crystal is the basic material which supports the development of information technology industry and photovoltaic industry, its performance affects and decides the development of related high technology industries directly. As the diameter of CZ silicon increase and the feature size of integrated circuit reduce continuously, defect control and quality assurance of the silicon single crystal are particularly important, especially the research about evolution behavior of "intrinsic gettering" structure which is based on new rapid thermal processing(RTP) in silicon wafer during the process of heat treatment.In recent years, the computer numerical simulation technology is increasingly used in materials microdefects evolution researches. Thereamong, phase field method which based on Ginzburg-Landau free energy theory, has become an important numerical simulation method for the study of material microdefects. Based on this method, the model building, programming and simulation data visualization processing can realize the simulation of material microdefects area evolution behavior, which has great theoretical and practical significance for studying the distribution and formation mechanism of material meso-micro defects.So far, many scholars at home and abroad have done a lot of simulation researches on the material structure evolution through phase field method. However, phase field simulation studies on defects such as oxygen precipitation evolution behavior in single crystal silicon wafer during annealing process are rarely reported. Therefore, phase field method is applied in this paper, a phase field model describing oxygen clusters’ and oxygen precipitation’s evolution behaviors in silicon wafer after RTP treatment was established, their evolution simulation in the process of annealing at low temperature and high temperature was realized respectively, the influence laws under different simulation conditions were studied and analyzed,phase field method’s application in the study of defects evolution in silicon single crystal was further explored.First of all, based on the material thermodynamics, crystal point defect physics, phase field theory and the related simulation assumptions, phase field models describing oxygen clusters’and oxygen precipitation’s evolution behaviors in silicon wafer after RTP treatment were established, including system free energy equation, defects evolution control equations, etc. A simulation algorithm based on finite difference method and Euler iterative method was identified, and the simulation program was compiled through Matlab language.Then, different initial simulation conditions were set, the simulation of oxygen clusters’evolution in low temperature annealing process and oxygen precipitation’s evolution in high temperature annealing process were achieved on computer with simulation program applied, compared with the experimental conclusions in related theories and literatures, the rationality of proposed model, algorithm and program could be preliminary verified.Finally, through further comprehensive simulation studies, the influence laws of initial vacancy concentration and low temperature annealing on oxygen clusters’ evolution and high temperature annealing on oxygen precipitation’s evolution were revealed, respectively:(1) during the period of low temperature annealing, as the annealing time extends, oxygen clusters’quantities increase unceasingly and its size grow slightly larger; (2) during the period of low temperature annealing, oxygen clusters’quantities increase with the increase of initial vacancy concentration, and first raise until the peak and then gradually reduce with increasing annealing temperature; (3) during the period of low temperature annealing, when initial vacancy concentration is higher than 1×1015 cm-3 and annealing temperature varies in the ranges from 1075 K to 1175 K, the amount of oxygen clusters is greater, and when initial vacancy concentration is less than 1×1012 cm-3 and annealing temperature is lower than 900 K, oxygen clusters could not exist; (4) during the period of high temperature annealing, as the annealing time extends, oxygen precipitation’s sizes grow increasingly, and its quantities first raise until the peak and then remain mainly unchanged; (5) during the period of high temperature annealing, with constant improvement of the annealing temperature, oxygen precipitation’s sizes increase unceasingly, its average size can be up to about 50-120 nm within annealing temperature ranging from 1000 K to 1500 K.It is verified that the established model and its algorithm have credible thermodynamics and experimental basis, simulation results achieved in this paper correspond with related experimental conclusions.