JUNCTION BUTTING IN SOI TRANSISTOR WITH EMBEDDED SOURCE/DRAIN

摘要

After forming source/drain trenches within a top semiconductor layer of a semiconductor-on-insulator (SOI) substrate, portions of the trenches adjacent channel regions of a semiconductor structure are covered either by sacrificial spacers formed on sidewalls of the trenches or by photoresist layer portions. The sacrificial spacers or photoresist layer portions shield portions of the top semiconductor layer underneath the trenches from subsequent ion implantation for forming junction butting. The ion implantation regions thus are confined only in un-shielded, sublayered portions of the top semiconductor layer that are away from the channel regions of the semiconductor structure. The width of the ion implantation regions are controlled such that the implanted dopants do not diffuse into the channel regions during subsequent thermal cycles so as to suppress the short channel effects.

主权项

1. A method of forming a semiconductor structure comprising:
forming a plurality of gate structures on a top semiconductor layer of a semiconductor-on-insulator (SOI) substrate; forming trenches in the top semiconductor layer between the gate structures, the trenches extending through a portion of the top semiconductor layer; forming sacrificial spacers on sidewalls of the gate structures and the trenches, the sacrificial spacers shielding portions of the top semiconductor layer underneath the sacrificial spacers; introducing dopants into un-shielded portions of the top semiconductor layer underneath the trenches to form doped regions in the top semiconductor layer, the doped regions contacting a buried insulator layer of the SOI substrate; removing the sacrificial spacers to expose undoped portions of the top semiconductor layer beneath the trenches; and forming doped epitaxial semiconductor regions in the trenches.