Patent ID: 8395212

Claim:
A structure comprising a field-effect transistor provided along an upper surface of a semiconductor body having body material of a first conductivity type, the transistor comprising: a channel zone of the body material; first and second source/drain (“S/D”) zones situated in the semiconductor body along its upper surface, laterally separated by the channel zone, and being of a second conductivity type opposite to the first conductivity type so as to form respective pn junctions with the body material, the first S/D zone comprising a main portion and a more lightly doped lateral extension laterally continuous with the main portion and extending laterally under the gate electrode such that the channel zone is terminated by the lateral extension and the second S/D zone along the body's upper surface, the second S/D zone being materially more lightly doped than the main portion of the first S/D zone; a gate dielectric layer overlying the channel zone; and a gate electrode overlying the gate dielectric layer above the channel zone; wherein: the body material is doped with semiconductor dopant of the first conductivity type; each pn junction reaches a maximum depth below the body's upper surface; the body material extends laterally under both S/D zones; the dopant of the first conductivity type is present in both S/D zones and has a concentration which locally reaches a main subsurface maximum concentration at a main subsurface body-material location extending laterally below largely all of each of the channel and S/D zones; the main subsurface body-material location occurs no more than 10 times deeper below the body's upper surface than the maximum depth of the pn junction for each S/D zone; and the concentration of the dopant of the first conductivity type decreases by at least a factor of 10 in moving upward from the main subsurface body-material location along a selected vertical line through a specified one of the S/D zones to the body's upper surface.