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We demonstrate a novel photoresist-compatible FinFET doping technique that combines the advantages of deposition and implantation. Energy and deposition thickness optimization for the Ion Assisted Deposition and Doping (IADD) process provides excellent doping of nMOS extensions, thus reducing external resistance R EXT . On current I ON is improved by 6-8% for L G of 26-30 nm and by 15% for L G of 20 nm, with better SCE and DIBL. IntroductionSource/drain extensions for fins require good sidewall doping for low resistance. For isolated fins, this could be achieved by conventional beamline ion implant (I/I) with large tilt angles. However, large tilt is not possible in real technologies, where tight fin pitches result in implant shadowing by photoresist, e.g. nMOS shadowing by the photoresist required to block pMOS regions [1]. Limiting amorphization/damage is also a challenge, as narrow fins provide limited seed for high quality epitaxial regrowth [2]. Additionally, beam line I/I with small implant angles, e.g., 7-10°, has I ON /SCE tradeoff [3] even though bulk FinFET has superior SCE controllability than planar FET. The origin of the I ON limitation is that the fin bottom region cannot be doped unless the implant energy is high. Short channel control is limited by the leakage current through the center of the fin just below the plane of the STI oxide, where gate control is weak. To address these concerns IADD, which uses simultaneous dopant deposition and knock-in, has been developed.

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