Selenium Segregation for Lowering the Contact Resistance in Ultrathin-Body MOSFETs With Fully Metallized Source/Drain

Dept. of Electr. & Comput. Eng., Nat. Univ. of Singapore, Singapore, Singapore
IEEE Electron Device Letters (Impact Factor: 2.75). 11/2009; 30(10):1087 - 1089. DOI: 10.1109/LED.2009.2028660
Source: IEEE Xplore


We report the first integration of selenium (Se) segregation contact technology in ultrathin-body (UTB) n-MOSFET featuring Ni fully silicided source and drain. During the Ni silicidation process, the implanted Se segregated at the NiSi-n-Si interface, leading to significant reduction of Schottky barrier height and contact resistance. The UTB n-MOSFETs integrated with Se segregation (SeS) contact technology show significant external series resistance reduction and drive current performance enhancement. Drain-induced barrier lowering and gate leakage current density are not adversely affected by the SeS process.

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    ABSTRACT: We demonstrate a novel technique to reduce the nickel silicide (NiSi) contact resistance Rcon in strained n-channel MOSFETs (n-FETs) with silicon carbon (Si:C) stressors, where a presilicide aluminum (Al) implant is performed and the Al profile is found to be affected by carbon (C). Al diffusion during silicidation is retarded by the presence of C and a high Al concentration is retained within the NiSi:C film, which is considered to be the main reason for electron barrier height ΦBn reduction in NiSi:C contacts. Ge preamorphization implant prior to Al implant further reduces the ΦBn to 0.44 eV. Integration of this technique in n-FETs with Si:C stressors achieves a 50% reduction in source/drain series resistance and 12% enhancement in saturation drive current. Negligible impact on the device short-channel effects is observed. When Al segregates at the NiSi/Si interface, the hole barrier height ΦBp is lowered, and such an Al profile can be used for the p-FETs. Al profile engineering shows a promise as a single-metal-silicide solution for selective Rcon optimization in CMOS.
    IEEE Transactions on Electron Devices 04/2013; 60(4):1310-1317. DOI:10.1109/TED.2013.2248367 · 2.47 Impact Factor

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