Abstract: A complementary insulated gate field effect transistor (10) having a partial channel. A gate electrode structure (29, 31) is formed on a dopant well (13, 14). An implant block mask (33, 38) is formed on a portion of the gate structure. An impurity material is implanted into the dopant well to form a dopant region (34, 39) having a first portion (36, 42) and a second portion (37, 41). The implant is of sufficient energy that a portion of the impurity material penetrates a portion gate electrode structure (29, 31) to form the second portion (37, 41) which serves as the partial channel. The partial channel provides the complementary insulated gate field effect transistor (10) with a low subthreshold swing, and improved saturation current and source/drain parasitic capacitance.

Abstract: A doping method using an oxide film and a nitride film on a trench wall as a protective film to prevent the impurity from diffusing into the silicon wafer adjacent to the outer wall and to enable the formation of a substantially flat interface between the first and the second trench to provide a smooth step difference between the first trench and the second trench is disclosed. A highly integrated semiconductor device having a trench comprising a first trench having a bottom and with a second trench formed in the bottom of the first trench with an interface between the first trench and the second trench characterized by the interface between the first and the second trench being substantially flat to provide a smooth step difference between the first trench and the second trench is also disclosed.