Impact of Millisecond Laser Anneal on the Thermal Stress- Induced Defect Creation in Si1-xGex Source /Drain Junctions

The purpose of this paper is to evaluate the impact of the laser anneal on the thermal stress induced defect creation in Si1-xGex S/D junctions. It is shown that several factors play a key role in the motion of the glide dislocations during the laser anneal process, when huge thermal stress gradients are present in both lateral and vertical directions: firstly, the stress levels prior to a post-epi implantation; secondly, the ion implantation conditions and finally, the laser energy beam conditions. Nomarski inspections of preferentially etched Si1-xGex/Si hetero-epitaxial junctions have been performed in order to analyze the laser-induced morphology changes. Additionally, I-V measurements were employed to further investigate the leakage current enhancement due to the thermal stress induced defect creation in the embedded Si1-xGex S/D junctions. Both analysis methods resulted in fully consistent results, revealing an increase in motion of dislocations and dislocation density only for the splits that already showed some relaxation induced-extended defects before the laser annealing process. Moreover, the only conditions where the extended defects prior to the laser anneal were observed were when a post-epi ion implantation was processed in the epilayers with 25%Ge (the highest Ge content studied).