Spectro-ellipsometric Studies of Amorphization and Thermal Annealing in Ion-implanted Silicon

The damage profiles in the P+, BF2 +, As+ and B+ ion-implanted silicon specimens are investigated using the nondestructive spectroscopic ellipsometry (SE) technique. The effective dielectric functions of the damaged layers are calculated using the Bruggeman's effective medium approximation, assuming that the damaged layer can be optically represented by the mixture of crystalline and amorphous silicon. By selectively using either the dielectric function of implanted amorphous silicon, or that of the relaxed amorphous silicon as the reference data for the amorphous silicon, we have improved the accuracy in modeling. The model parameters regarding the damaged layer thickness and the degree of amorphization are found to depend on implanting ion species, implantation energies, and total doses. Also, the implantation induced damage profiles are computer simulated and compared with the SE results. When annealed at lower temperatures, implanted amorphous silicon turns into the relaxed amorphous silicon and starts to recrystallize from the interface of the c-Si side due to solid-phase epitaxial growth. At annealing temperatures higher than 600°C, relaxed amorphous layers become crystalline silicon.