Analysis of Si:C on Relaxed SiGe by Reciprocal Space Mapping for MOSFET Applications

Silicon-germanium (SiGe) or silicon-carbon alloys (Si:C) are used as embedded stressors in silicon devices since they increase the channel strain and the performance as a result of the lattice mismatch. The strain properties of silicon with carbon doped on a relaxed SiGe virtual substrate are examined using reciprocal space mapping. Due to the ∼52% lattice mismatch between silicon and carbon, the silicon with a carbon-doped surface channel is under greater strain than it on a relaxed SiGe virtual substrate. This suggests that the carrier mobility could be significantly enhanced. The extracted electron mobility of a n-type metal-oxide-semiconductor field-effect transistor (MOSFET) device with 0.25% carbon shows the enhancement of 22% and 65% for the peak mobility and a large electric field (1 MV/cm), respectively.