A method for manufacturing a vertical power component on a substrate formed of a lightly-doped silicon wafer, including the steps of boring on the lower surface side of the substrate a succession of holes perpendicular to this surface; diffusing a dopant from the holes, of a second conductivity type opposite to that of the substrate; and boring similar holes on the upper surface side of the substrate to define an isolating wall and diffuse from these holes a dopant of the second conductivity type with a high doping level, the holes corresponding to the isolating wall being sufficiently close for the diffused areas to join laterally and vertically.