Modulation of the Schottky Barrier Height for CMOS advanced contacts

Contact schemes for scaled Si, SiGe and Ge channel MOSFET 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. Contacts to n + Ge with contact resistivity (ρc) values of ~ 1.5 × 10− 8 Ω cm2 are achieved using n + Si passivation. Further, methods for SBH reduction to nSi, 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 leading to SBH = 0.00 ± 0.01 eV.

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