Transmission Electron Microscopy Investigation Of Oxygen Precipitation And Induced Defects In Czochralski Silicon

Microelectronics based on silicon was driving the high-speed development of economy, science and technology of the world in the last century. As we know, silicon is the most important semiconductor material and it was, is and will also remain the main semiconductor material during the next decades, manifesting that the progress in silicon semiconductor material can influence significantly the economy, national defense and modernization of our country. Thus, it is important to investigate the interaction between the impurities and defects and also the influences of the annealing temperature, ambient, duration and stress on the kinetics and thermodynamics of the generation of defects.In the dissertation, the formation mechanism of the oxygen precipitates and the extended defects generated in Czochralski silicon (Cz-Silicon) specimens were investigated by mean of Transmission Electron Microscopy (TEM). The influence of the annealing temperature, ambient, duration and stress on the distribution, density and morphology of the defects generated in different kind of specimens (including specimens grown under the Nitrogen or Argon ambient, pre-annealed under high pressure of 109 Pa, heavily doped and Rapid thermal annealing (RTA), respectively) have been well investigated and understood.Firstly, the influence of the high pressure pre-annealing on the formation mechanism of the oxygen precipitate and extended defects has been systematically investigated. It found that: 1) Annealing at 450# under high-pressure for 10 hours results in the generation of sphere-like oxygen precipitates with high density but small size, indicating that high pressure can change the morphology of oxygen precipitate to a great extent. 2) It revealed by electrical property measurement that the generation rate and velocity of the thermal donors can be enhanced during annealing at 450癈 under high-pressure, indicating that high pressure can change the formation kinetics and thermodynamics of thermal donors and manifesting that the thermal donors is closely related with the oxygen precipitates with small size. But, it found that the annihilation of the thermal donors generated both in the specimens annealed under atmosphere and high pressure shown no difference, indicating that the annihilation behavior of the thermal donors annealed at 650# is similar. And it also found that the nitrogen doping have no significant influence on the generation and annihilation of thermal donors when annealed at 450# under high pressure. 3) It reveals that oxygen precipitate-related dislocation can be observed in the specimen annealed at 957# under high pressure for 5 hours and oxygen precipitates with the size of about 50nm can be observed in the specimen annealed at 1130# under high pressure for 5 hours, indicating that high pressure can stabilize the oxygen precipitates with small size. By analyzing the influence of the stress induced by the high pressure on the generation of point defects, we propose a detailed and satisfying explanation about the formation of oxygen precipitation with high density but small size and the enhancement of the thermal donors in the specimen annealed under high pressure. It reveals that the stress exerted on specimens by high pressure can change the concentration of point defects, thus influence the formation kinetics and thermodynamics of defects to a great extent.Secondly, the influence of nitrogen doping on the formation mechanism of defects has also been systematically investigated. It found that: 1) Nitrogen doping can change the morphology of grown-in oxygen precipitates. It found that grown-in oxygen precipitates with high density but small size, about 5nm, were generated in nitrogen doping specimen. 2) Nitrogen doping can enhance the oxygen precipitation both in high temperature and low temperature annealing. 3) Nitrogen doping can influence the generation kinetics and thermodynamics of oxidation-induced stacking fault (OSF), it is found that the size of the oxidation-induced stacking faults (OSFs) decreased with th...