Modulation of the Schottky Barrier Height for Advanced Contact Schemes

Contact schemes for scaled Si, SiGe and Ge channel MOSFETs devices are discussed, consistent with an approach based on SiGe alloys with low Schottky Barrier Height (SBH) for pMOS and Si contacts for nMOS, making reduction of the SBH to nSi critical. Methods for SBH reduction, and their underlying mechanisms, are studied. Accurate cryogenic CV measurements were used to extract SBH. We show that chalcogenide segregation can be effective in lowering the SBH by a dipole effect, while MIS contacts have a partial un-pinning effect. SBH=0.00 +/- 0.01 eV was achieved.