A method for forming at least one doped region of a transistor includes providing a stack having an insulating layer, an active layer, and a gate pattern having a first lateral flank and removing a first portion of the active layer not overlaid by the gate pattern and extending down to the gate pattern, at the edge of a second portion of the active layer overlaid by the gate pattern, so as to expose an edge of the second portion. The edge extends substantially in a continuation of the lateral flank of the gate pattern. The method also includes forming a first spacer having an L shape and having a basal portion in contact with the insulating layer and a lateral portion in contact with the lateral flank; forming a second spacer on the first spacer; removing the basal portion of the first spacer by selective etching with respect to the second spacer, so as to expose the edge of the second portion; and forming the doped region by epitaxy from the exposed edge.