Patent ID: 7838930

Claim:
A structure comprising a principal field-effect transistor (“FET”) which comprises: a principal channel zone of principal body material of a semiconductor body having an upper semiconductor surface, the body material being sufficiently doped with semiconductor dopant of the first conductivity type as to be of the first conductivity type; a pair of principal source/drain zones situated in the semiconductor body along the upper semiconductor surface, laterally separated by the channel zone, and being of a second conductivity type opposite to the first conductivity type, the body material comprising (a) a principal subsurface body-material portion which underlies the channel and source/drain zones and which, at its closest to the source/drain zones, is no more than 10 times deeper below the upper semiconductor surface than the source/drain zones and (b) a principal surface-adjoining body-material portion which extends to the upper semiconductor surface, which contains the channel zone, and which overlies and meets the subsurface body-material portion, the dopant of the first conductivity type in the body material having a concentration that largely undergoes a step decrease by at least a factor of 10 in crossing from the subsurface body-material portion upward into the surface-adjoining body-material portion and, in moving further upward through the surface-adjoining body-material portion to a specified one of the source/drain zones, remains at least a factor of 10 lower than in the subsurface body-material portion; a principal gate dielectric layer overlying the channel zone; and a principal gate electrode overlying the gate dielectric layer above the channel zone.