This invention discloses a method for manufacturing a semiconductor power device on a semiconductor substrate supporting a . drift region composed of an epitaxial layer. The method includes a first step of growing a first epitaxial layer followed by forming a first hard mask layer on top of the epitaxial layer; a second step of applying a first implant mask to open a plurality of implant windows and applying a second implant mask for blocking some of the implant windows to implant a plurality of dopant regions of alternating conductivity types adjacent to each other in the first epitaxial layer; and a third step of repeating the first step and the second step by applying the same first and second implant masks to form a plurality of epitaxial layers, each of which is implanted with the dopant regions of the alternating conductivity types. Then the manufacturing processes proceed by carrying out a device manufacturing process on a top side of the epitaxial layer on top of the dopant regions of the alternating conductivity types with a diffusion process to merge the dopant regions of the alternating conductivity types as doped columns in the epitaxial layers.