LOW-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 0.3-0.55. X-ray diffraction and cross-sectional t ransmission electron microscopy were used to study the crystal structu re, whereas X-ray photoelectron spectroscopy was used to determine the film composition and the chemical bonding states of the elements. In low-temperature (less than or equal to 600 degrees C) annealing, the c onductivity, the dopant activation, and the Hall effect mobility decre ased during extended annealing. The effective activation of phosphorus was less than 20% and decreased with increasing Ge content, Boron act ivation could reach above 70%. It was also found that Si1-xGex could b e oxidized at 600 degrees C in a conventional furnace even with N-2 pr otection, especially for phosphorus doped films with high Ge content. Consequently, a low-temperature SiO2 capping layer is necessary during extended annealing.