Abstract: A Trench gate MOS field-effect transistor having a narrow, lightly doped, region extending from a channel accommodating region (3) of same conductivity type immediately adjacent the trench sidewall. The narrow region may be self-aligned to the top of a lower polysilicon shield region in the trench or may extend the complete depth of the trench. The narrow region advantageously relaxes the manufacturing tolerances, which otherwise require close alignment of the upper polysilicon trench gate to the body-drain junction.

Abstract: A Trench gate MOS field-effect transistor having a narrow, lightly doped, region extending from a channel accommodating region (3) of same conductivity type immediately adjacent the trench sidewall. The narrow region may be self-aligned to the top of a lower polysilicon shield region in the trench or may extend the complete depth of the trench. The narrow region advantageously relaxes the manufacturing tolerances, which otherwise require close alignment of the upper polysilicon trench gate to the body-drain junction.

Abstract: A metal-oxide-semiconductor trench-gate semiconductor device in which a substantially intrinsic region (40) is provided below the gate trench (20), which extends from the base of the trench, substantially across the drain drift region (14) towards the drain contact region (14a), such that when the drain-source voltage falls during turn-on of the device its rate of decrease is higher. This reduces the switching losses of the device. The substantially intrinsic region (40) may, for example, be formed by implanting a region below the trench (20) with a damage implant.

Abstract: A localised reduced lifetime region (1,25,41) is provided in a semiconductor device formed substantially of silicon. A predetermined concentration of carbon is provided in the region, and then the body is heated to incorporate a lifetime controlling impurity substantially within the carbon region. It is believed that the association between the impurity ions (M+) and the carbon atoms (C) on silicon lattice sites produces C-M+ complexes with significant capture cross-sections. The carbon may be provided by addition during epitaxial growth of silicon material, during bulk growth of the silicon, or by implantation and/or diffusion.

Abstract: A localised reduced lifetime region (1,25,41) is provided in a semiconductor device formed substantially of silicon. A predetermined concentration of carbon is provided in the region, and then the body is heated to incorporate a lifetime controlling impurity substantially within the carbon region. It is believed that the association between the impurity ions (M+) and the carbon atoms (C) on silicon lattice sites produces C-M+ complexes with significant capture cross-sections. The carbon may be provided by addition during epitaxial growth of silicon material, during bulk growth of the silicon, or by implantation and/or diffusion.

Abstract: A metal-oxide-semiconductor trench-gate semiconductor device in which a substantially intrinsic region (40) is provided below the gate trench (20), which extends from the base of the trench, substantially across the drain drift region (14) towards the drain contact region (14a), such that when the drain-source voltage falls during turn-on of the device its rate of decrease is higher. This reduces the switching losses of the device. The substantially intrinsic region (40) may, for example, be formed by implanting a region below the trench (20) with a damage implant.