Reduction of parasitic bipolar transistor action and punchthrough susceptibility in MOSFETs using Si/Si1-xGex sources and drains

Abstract

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 bipolar action and punchthrough susceptibility. The authors compare the properties of elevated source and drain devices with and without Si/sub 1-x/Ge/sub x/ 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 Si/sub 0.8/Ge/sub 0.2/ devices.