A manufacturing method of an anchorage element of a passivation layer, comprising: forming, in a semiconductor body made of SiC and at a distance from a top surface of the semiconductor body, a first implanted region having, along a first axis, a first maximum dimension; forming, in the semiconductor body, a second implanted region, which is superimposed to the first implanted region and has, along the first axis, a second maximum dimension smaller than the first maximum dimension; carrying out a process of thermal oxidation of the first implanted region and second implanted region to form an oxidized region; removing said oxidized region to form a cavity; and forming, on the top surface, the passivation layer protruding into the cavity to form said anchorage element fixing the passivation layer to the semiconductor body.