Patent ID: 8629027

Claim:
A method of fabricating a structure comprising a field-effect transistor from a semiconductor body having body material of a first conductivity type, the method comprising: defining a gate electrode above, and vertically separated by a gate dielectric layer from, a portion of the body material intended to be a channel zone; and subsequently introducing (i) semiconductor dopant of the first conductivity type into at least the intended channel-zone portion of the body material and (ii) composite semiconductor dopant of a second conductivity type opposite to the first conductivity type into the semiconductor body such that: (a) the composite dopant of the second conductivity type forms first and second source/drain (“S/D”) zones of the second conductivity type laterally separated by the channel zone, (b) 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, (c) the channel zone is terminated by the S/D extensions directly below the gate dielectric layer, (d) the S/D extension of the second S/D zone is more lightly doped than the S/D extension of the first S/D zone and extends deeper into the semiconductor body than the S/D extension of the first S/D zone, and (e) a pocket portion of the body material more heavily doped than laterally adjacent material of the body material and defined at least partially by the dopant of the first conductivity type extends largely along only the first of the S/D zones and into the channel zone so as to cause the channel zone to be asymmetric with respect to the S/D zones.