| Information society is on the base of microelectronic industry that is built on the semiconductor silicon material. The concentration and the existed form of oxygen, carbon, and nitrogen in silicon have a great influence on its electronic and mechanical property. And these impurities also affect the electronic behavior and yield of devices. The behavior of oxygen, carbon, and nitrogen related to thermal donors, new donors, donors related to nitrogen, and oxygen precipitates in silicon have been intensively investigated last decades. However, the interaction of these impurities and the structure of the defects associated with these impurities are not still clear.In this thesis, the behavior of oxygen, carbon and nitrogen impurities and their interaction has been investigated. It was found that the intensity of FTIR NB peaks of nitrogen was related with NA peaks and their companied peak NA3, while NB and NA peaks in float zone silicon was not the linear relationship. Furthermore, the NB, and NA1 was linear relationship, while NA, was proportion to the plus of oxygen and nitrogen concentration and NA3 was proportion to the plus of the concentration of nitrogen and the cubic of interstitial oxygen concentration. Based on the results, the microstructure model of C-O and N-O complex was set up. It was suggested that the so-called C-O and N-0 complexes were actually C-Si-O and (N-N)-Si-O complexes in structure. There were four kinds of vibration modes (Si0, Si1, Si2, and Si3) for the silicon atoms that bonded with carbon or oxygen. The vibration and rotation of different C-Si, and N-Si bond cause the seven and five absorption peaks in FTIR spectrum, respectively.The electrical property of Cz silicon doped nitrogen was also investigated. The experiments indicate that the (N-N)-Si-O complexes as shallow donors were produced. The shallow donors were produced in the temperature range of 450℃ to 1100℃. And the lower the formation temperature of the donor, the higher the concentration of the donor related to nitrogen was. On the contrary, the concentration of donors related to nitrogen would be low if the donors formed lower at 450℃. Moreover, it is considered that ten nitrogen atoms react with oxygen to generate 1-2 or 5-6 donors. The mechanism of the formation of (N-N)-Si-O complexes was also discussed.The experiments of new donors shows that they could form in the temperature range of 450 ℃ to 1100℃, but not in the range of 600~800℃ accepted previously. It was found that the newdonors were much similar to the shallow donors related with nitrogen. In general, new donors were believed to closely related to C-O complexes. Their nuclei formation rate was slow and they had less effect on the carrier concentration of silicon if the concentration of carbon was low at the tail of silicon crystal. However, the concentration of new donors was much higher than that of donors related to nitrogen if the annealing time was long enough.It was observed in the experiments that there were two kinds of nuclei mechanism of oxygen precipitates. One was not related to the absorption peak at 1230 cm-1 in the FTIR spectrum. The oxygen precipitates with high density were about 10-30 nm in size, in which carbon was involved in the nuclei and growth process. The other was associated with the absorption peak at 1230cm-1 in the FTIR spectra. Those oxygen precipitates with low density were about 100-300 nm in size, in which the carbon was not involved. Moreover, the morphology of oxygen precipitates was found to be dependent of the nuclei.The experiments also show that carbon and nitrogen could depress the formation of thermal donors while the effect of nitrogen was limited relatively. There was no influence of nitrogen on the concentration of thermal donors after long time annealing. Therefore, based on Si-O complex, it is suggested that there are three kinds of mechanism for the agglomerate of the super-saturation oxygen in silicon crystal. 1) Interstitial oxygen and silicon atoms interacted each other and formed the tetrahedron...
|
PDF Full Text Request