Formation of germanium shallow junction by flash annealing

We have investigated flash-lamp annealing (FLA) of germanium wafers doped with phosphorous and boron introduced in the crystal by ion implantation. Annealing was performed by using pre-heating at 400–450 °C in a conventional rapid thermal processing (RTP) unit and a fast (3–20 ms) FLA annealing at 800 °C or 900 °C. Diffusion of P is suppressed during the 800 °C–20 ms FLA annealing, while concentration-enhanced diffusion occurs upon 900 °C FLA anneals. Importantly, in both cases P activation seems to be enhanced by the FLA process. However, junction stability following the FLA process and possible deactivation are a concern.In contrast, the FLA process applied to B-doped pre-amorphized Ge layers does not show advantages as compared to a RTP conventional annealing combined with a solid phase epitaxial regrowth, in terms of B activation level.