An investigation was made of the effect of position and dose of a separate F co-implant on the activation and diffusion behavior of Ge pre-amorphized B implants. Some Ge pre-amorphized Si was implanted with B, and F was subsequently implanted with different energies and doses to place it either at the projected range of the B implant, or between the B profile and the amorphous-crystalline interface, or at this interface. The wafers were spike annealed at 950 to 1050C. In terms of sheet resistance it was found that the superposition of B and F profiles leads to decreased activation compared to the wafers without any F implant. Increased B activation was seen for all the other cases with the biggest effects for the highest F dose. The positioning of F either between the B projected range and the end of range or at the end of range leads to more box-shaped B profiles with shallower junction depth than the reference wafer.

Effect of Fluorine on the Activation and Diffusion Behavior of Boron-Implanted Pre-Amorphized Silicon. S.Paul, W.Lerch, B.Colombeau, N.E.B.Cowern, F.Cristiano, S.Boninelli, D.Bolze: Journal of Vacuum Science & Technology B, 2006, 24[1], 437-41