1Low Temperature Annealing of Polycrystalline Si1-xGex after Dopant Implantation

Hall Effect measurement was employed to study the isothermal annealing of boron or phosphorus implanted polycrystalline Si1-xGex thin films, with x varying from 0.3 to 0.55. X-ray diffraction and cross-sectional transmission electron microscopy were used to study the crystal structure, while X-ray photoelectron spectroscopy was used to determine the film composition and the chemical bonding states of the elements. In low temperature (£600) annealing, the conductivity, the dopant activation, and the Hall Effect mobility decreased during extended annealing. The effective activation of phosphorus was less than 20 % and decreased with increasing Ge content. Boron activation could reach above 70%. It was also found that Si1-xGex could be oxidized at 600 in a conventional furnace even with N2 protection, especially for phosphorus doped films with high Ge content. Consequently, a low temperature SiO2 capping layer is necessary during extended annealing