Method of making reverse lightly doped drain (ldd) for buried n+

Abstract

A silicon semiconductor device has buried conductor lines formed therein. A layer of gate oxide, conductive structures, and spacer structures adjacent to the conductive structures on the gate oxide layer are formed. The substrate has implanted dopant ions of a relatively low level of surface concentration in the semiconductor material below the remainder of the conductive structures. The substrate has implanted dopant ions of a relatively medium level of surface concentration in the semiconductor material below the spacer structures. The substrate has implanted dopant ions of a relatively high level of surface concentration in the semiconductor material below the remainder of the substrate. Thus leakage is reduced by the profile of surface concentration of dopant in the semiconductor material of the substrate.