Patent ID: 8377768
Filing Date: 2013-02-19
Classification: H01L

Abstract:
1. A method of fabricating a structure comprising a plurality of like-polarity field-effect transistors (“FETs”) from a semiconductor body having body material of a first conductivity type, the method comprising: defining a gate electrode for each FET such that the gate electrode is situated above, and vertically separated by a gate dielectric layer from, a portion of the body material intended to be a channel zone for that FET; and introducing composite semiconductor dopant of a second conductivity type opposite to the first conductivity type into the semiconductor body to form, for each FET, a pair of source/drain (“S/D”) zones of the second conductivity type laterally separated by that FET's channel zone and forming a pair of pn junctions respectively with the body material such that each S/D zone comprises a main S/D portion and a more lightly doped lateral S/D extension laterally continuous with the main S/D portion and extending laterally under the gate electrode and such that the channel zone is terminated by the S/D extensions directly below that FET's gate dielectric layer wherein the act of introducing the composite dopant of the second conductivity type includes (a) introducing first semiconductor dopant of the second conductivity type into the semiconductor body to at least partially define the S/D extension of a specified one of the S/D zones of a first of the FETs and (b) introducing second semiconductor dopant of the second conductivity type into the semiconductor body to at least partially define the S/D extension of a specified one of the S/D zones of a second of the FETs, the first dopant of the second conductivity type being introduced into the semiconductor body at a higher dosage than the second dopant of the second conductivity type so that the S/D extension of the specified S/D zone of the first FET is more heavily doped than the S/D extension of the specified S/D zone of the second FET.