The Defects In Heavy Boron-doped Czochralski Silicon

Heavy boron-doped CZ silicon wafer is widely used as the substrate for the p/p-epitaxial wafer. Boron with high concentration would improve the electricity performance, and also impact other defects in CZ silicon. In this thesis, the dislocation and oxygen precipitation in heavy boron-doped CZ silicon have been investigated. The primary results are described in the following.(1) Grow-in dislocations in heavy boron-doped CZ silicon has been investigated. It is found that, when the concentration of boron doped is higher than 7 X 1019 cm-3, the grow-in dislocations generate in the CZ silicon. The dislocation distribute mainly in some special area of crystal and do not extend to the whole crystal. It shows that, after annealing the Si wafer in a variety of conditions, the dislocations can be decreased. Particularly after annealing at 1000℃for 1 h. the dislocations could be dissolved.(2) The effect of boron concentration on the dislocations in silicon has been investigated. It is indicated that high concentrations of boron could lock the dislocations. Increasing boron concentration will increase the sliding activation energy; decrease the sliding velocities and the maximum sliding distance; and then the time to arrive at the maximum sliding distance would get longer.(3) The influence of boron concentration on the oxygen precipitation has been investigated. It is revealed that, for low-high two steps annealing, the boron concentration at the shifting point would get lower with more nucleation time and higher temperature. For single-step annealing, raising the annealing temperature could decrease the density of oxygen precipitation and the boron concentration at the shifting point.