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

摘要

Mechanical strain can be used to improve electronic transportproperties in advanced short gate length Si-based Metal OxideSemiconductor Field Effect Transistors. The controlledintroduction of strain in the channel area of transistors (thanks torecessed SiGe sources and drains, contact etch stop layers or toprevious processing at the wafer scale) can indeed increase thecarrier mobility by a factor of up to two. We have used here ultravioletand visible Raman Spectroscopy to study the processes thatcan influence strain during the elaboration of strained Si OnInsulator (sSOI) substrates. The results obtained during analyses oftensily-strained Si layers grown on polished Si1-xGex virtualsubstrates (VS) show that the strain can be preserved for 20% ofGe. However, we observed a relaxation of the strain for 40% Ge,after layer transfer onto oxidized silicon. A definite strainrelaxation at the edges of lines patterned in sSOI wafers was alsodemonstrated. A good agreement between experimental results andsimulation has been achieved