Reduction of parasitic bipolar transistor actionand punchthrough susceptibilityin MOSFETs using Si/Si 1-x Ge x sources and drains

Silicon CMOS devices are subject to some limitations as the dimensions are scaled down for VLSI applications. The incorporation of SiGe into the p-channel device can reduce parasitic bipoiar action and punchthrough susceptibility. The authors compare the properties of elevated source and drain devices with and without Si1-xGex in the source and drain regions. We show that the parasitic bipolar gain is reduced by a factor of 18 and that the punchthrough effects seen in silicon devices are absent in the Si0.8Ge0.2 devices.