Doped spacer liner for improved transistor performance

Abstract

Semiconductor devices with improved transistor performance are fabricated by ion-implanting a dopant into the oxide liner to prevent or substantially reduce dopant out-diffusion from the shallow source/drain extensions. Embodiments include ion implanting a P-type dopant, such as B or BF2, using the gate electrode as a mask, to form shallow source/drain extensions, depositing a conformal oxide liner, and ion implanting the P-type impurity into the oxide liner at substantially the same dopant concentration as in the shallow source/drain extensions. Subsequent processing includes depositing a spacer layer, etching to form sidewall spacers, ion implanting to form deep moderate or heavy source/drain implants and activation annealing.

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