Patent ID: 6111291
Filing Date: 2000-08-29
Classification: H01L

Abstract:
A MOS transistor with high voltage sustaining capability and low closing resistance comprising:a substrate comprising a doping of a first conductive type;a well area formed in the substrate and provided with a doping of a second conductive type opposite to the first conductive;source and drain areas of the first conductive type formed in the well area;a gate comprising a gate oxide layer and arranged between the source area and the drain area, the gate having drain-side end region arranged at a distance from the drain area, and a field oxide web arranged below the drain-side end region of the gate; anda drain extension region comprising a doping of the first conductive type and having the drain area arranged therein, with the drain extension region reaching below the gate oxide layer of the gate;whereinthe drain extension region is formed by ion implantation and comprises a first partial area arranged below the field oxide web and a second partial area joining the first partial area in the direction of the drain area, and having at least a partial area of the drain area arranged therein or having the drain area bordering thereon, with the concentration of the electrically active doping of the first conductive type being smaller in the first partial area of the drain extension region than in the second partial area of the drain extension region, but larger than in the rest of the region of the drain extension region; andwherein the well area is formed by ion implantation of two partial areas spaced from each other by a distance region aligned with the first and the second partial area, and by subsequent thermally induced diffusion, wherein these two partial areas after diffusion are connected to each other within a connection region (c) corresponding to the first and the second partial area of the drain extension region, and the concentration of the doping of the second conductive type is lower in this connection region (c) than in the rest of the well area.