Diffusion and activation of Boron and Phosphorus in preamorphized and crystalline Germanium using ultra fast spike anneal

In this work, the influence of a pre-amorphization implant (PAI) combined with a single-step spike anneal on the junction formation in Germanium is inverstigated, both for n-type dopant with Phosphorus (P) as well as for p-type dopant Boron (B). The experiments were performed on a 1.5µm Germanium (Ge) epi-layer onto 200mm Silicon (Si) substrate. After implantation both with or without PAI, the dopant activation was achieved using a single step, conductive, spike anneal (ranging 550ºC–900ºC) in a ASM Levitor
^®
system. Junction depth (Xj) and electrical activation levels (N
act
) were characterized using secondary-ion-mass spectroscopy (SIMS) and sheet resistance Rs measurements. The results show that the combination of the high ramp rates with single step spike anneal on the one hand and PAI on the other hand, improved junctions characteristics compared to standard implant and RTP (Rapid Thermal Processing) conditions. The SIMS results show a reduction of junction depth for pre-amorphized junction after activation annealing up to 20% with P and 42% with B at 5×10
¹⁸
cm
⁻³
dopant concentration. In addition, electrical activation levels up to 4,95×10
²⁰
cm
⁻³
were achieved for the p-type implants.