UV AND VISIBLE RAMAN SPECTROSCOPYAPPLIED TO sSi/Si1-XGeX AND sSOISTACKS

摘要

Mechanical strain can be used to improve electronic transportrnproperties in advanced short gate length Si-based Metal OxidernSemiconductor Field Effect Transistors. The controlledrnintroduction of strain in the channel area of transistors (thanks tornrecessed SiGe sources and drains, contact etch stop layers or tornprevious processing at the wafer scale) can indeed increase therncarrier mobility by a factor of up to two. We have used here ultravioletrnand visible Raman Spectroscopy to study the processes thatrncan influence strain during the elaboration of strained Si OnrnInsulator (sSOI) substrates. The results obtained during analyses ofrntensily-strained Si layers grown on polished Si1-xGex virtualrnsubstrates (VS) show that the strain can be preserved for 20% ofrnGe. However, we observed a relaxation of the strain for 40% Ge,rnafter layer transfer onto oxidized silicon. A definite strainrnrelaxation at the edges of lines patterned in sSOI wafers was alsorndemonstrated. A good agreement between experimental results andrnsimulation has been achieved