Patent ID: 7785971

Claim:
A method of fabricating first and second opposite-polarity field-effect transistors from a semiconductor body having (i) first body material of a first conductivity type and (ii) second body material of a second conductivity type opposite to the first conductivity type, the method comprising: separately introducing (i) first, second, and third body-material semiconductor dopants of the first conductivity type into the first body material such that the three body-material dopants of the first conductivity type reach respective maximum dopant concentrations at three respective materially different locations in the first body material and (ii) first and second body-material semiconductor dopants of the second conductivity type into the second body material such that the two body-material dopants of the second conductivity type reach respective maximum dopant concentrations at two respective materially different locations in the second body material; subsequently defining (i) a gate electrode for the first transistor above, and vertically separated by gate dielectric material for the first transistor from, a portion of the first body material intended to be a channel zone for the first transistor and (ii) a gate electrode for the second transistor above, and vertically separated by gate dielectric material for the second transistor from, a portion of the second body material intended to be a channel zone for the second transistor; and subsequently introducing (i) further semiconductor dopant of the second conductivity type into the semiconductor body to form a pair of source/drain zones of the second conductivity type for the first transistor laterally separated by its channel zone and (ii) further semiconductor dopant of the first conductivity type into the semiconductor body to form a pair of source/drain zones of the first conductivity type for the second transistor laterally separated by its channel zone such that, upon completion of fabrication of the transistors, (a) the semiconductor body has an upper surface to which the channel and source/drain zones extend, (b) the location of the maximum concentration of each body-material dopant of the first conductivity type extends continuously laterally so as to underlie at least part of each of the first transistor's source/drain zones below the body's upper surface, and (c) the location of the maximum concentration of each body-material dopant of the second conductivity type extends continuously laterally so as to underlie at least part of each of the second transistor's source/drain zones below the body's upper surface.