Field-implant-free isolation by double-well split drive-in

A double-well CMOS concept well suited to conventional and state-of-the-art isolation techniques is presented. Sufficient field doping is achieved by solely distributing the well drive-in thermal budget before and after field oxidation. Segregation effects, in particular dopant loss in the p-well, are compensated. At the same time the body factor and parasitic capacitances are kept low. The split drive-in approach makes channel-stop implants and corresponding lithography steps superfluous. The field doping adjustment is self-aligned, a very significant advantage in submicrometer regime processing.<>