Laser Annealing of Amorphous Germanium on Silicon–Germanium Source/Drain for Strain and Performance Enhancement in pMOSFETs

We report the first demonstration of a novel germanium-enrichment process for forming a silicon-germanium (SiGe) source/drain (S/D) stressor with a high Ge content. The process involves laser-induced local melting and intermixing of a Ge layer with an underlying Si
_0.8
Ge
_0.2
S/D region, leading to a graded SiGe S/D stressor with a significant increase in the peak Ge content. Various laser fluences were investigated for the laser annealing process. The process is then successfully integrated in a device fabrication flow, forming strained silicon-on-insulator p-channel field-effect transistors (p-FETs) with a high Ge content in SiGe S/D. A drive current enhancement of ~ 12% was achieved with this process, as compared to a strained p-FET with Si
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Ge
_0.2
S/D p-FETs. The
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_Dsat
enhancement, primarily attributed to strain-induced mobility improvement, is found to increase with decreasing gate lengths.