METHOD OF MAKING IGFET Russian patent published in 1994 - IPC

FIELD: methods of making IGFET large-scale integrated circuits. SUBSTANCE: IGFET is made by forming gate with vertical walls onto surface of semiconductor silicon plate with the first type of conductivity. Slowly diffusing impurity with the second type of conductivity is introduced into the plate at both sides of the gate by ion implantation. Source-drain firing areas of implanted impurity are created; these areas are low doped. Dielectric layer is deposited onto the surface, which has step relief. Close-to-wall dielectric areas are produced by anisotropic plasma etching of deposited layer. Slowly diffused second-type conductivity impurity is ion implanted into the plate on both sides of close-to-wall areas. Quickly diffusing impurity with the same type of conductivity is ion implanted and string doped source-drain areas are produced simultaneously by firing, as well as intermediate areas, which have degree of doping, as be more, than low doped, but lower than strong-doped ones. As a result diffusion profile is smoothed and short-channel effects are attenuated. EFFECT: improved efficiency. 2 dwg, 1 tbl