Structure and fabrication of insulated-gate field-effect transistor with hypoabrupt change in body dopant concentration below source/drain zone

摘要

An insulated-gate field-effect transistor (100, 100V, 140, 150, 150V, 160, 170, 170V, 180, 180V, 190, 210, 210W, 500, 510, or 530; or 220, 220W, or 540) is provided with a hypoabrupt vertical dopant profile below one (104; or 264 or 564) of its source/drain zones for reducing the parasitic capacitance along the pn junction between that source/drain zone and adjoining body material (108; or 268 or 568). In particular, the concentration of semiconductor dopant which defines the conductivity type of the body material increases by at least a factor of 10 in moving from that source/drain zone down to an underlying body-material location no more than 10 times deeper below the upper semiconductor surface than that source/drain zone.