Method for forming an electronic device intended to receive at least one fully depleted (FDSOI) transistor and at least one partially depleted (PDSOI) transistor, from a stack of layers comprising at least one insulating layer topped with at least one active layer made of a semiconductor material, the method comprising at least the following steps: - forming at least one insulating trench through the thickness of the active layer to define in said active layer, on either side of the insulating trench, at least one first active region whereon at least one PDSOI transistor is intended to be formed and at least one second active region wherein at least one FDSOI transistor is intended to be formed; - forming, on top of the at least one first active region and on a part of the insulating trench, a masking layer without covering the at least one second active region and without covering a part of the insulating trench; - etching simultaneously by dry etching so as to form etched zones: ∘ a part of the thickness of the active layer of the at least one second active region so as to form at least one second thinned active region and to obtain in the at least one second thinned active region a smaller thickness of the active layer than in the at least one first active region, ∘ at least one part of the thickness of the non-covered part of the insulating trench so as to form an etched part of the insulating trench, ∘ and the entire masking layer, - adjusting, after the dry etching step, the height of the surface of the at least one second thinned active region to the height of the surface of said an etched part of the insulating trench, the step of adjusting the height of the surface of the at least one second thinned active region to the height of the surface of said etched part of the insulating trench comprising at least the following steps: - oxidising at least one portion of the second thinned active region so as to form a sacrificial oxide layer; - partially removing the sacrificial oxide layer so as to form a residual sacrificial oxide layer and such that the surface of the residual sacrificial oxide layer is at the same height as the surface of the etched part of the insulating trench. - forming at least one insulating trench through the thickness of the active layer to define in said active layer, on either side of the insulating trench, at least one first active region whereon at least one PDSOI transistor is intended to be formed and at least one second active region wherein at least one FDSOI transistor is intended to be formed; - forming, on top of the at least one first active region and on a part of the insulating trench, a masking layer without covering the at least one second active region and without covering a part of the insulating trench; - etching simultaneously by dry etching so as to form etched zones: ∘ a part of the thickness of the active layer of the at least one second active region so as to form at least one second thinned active region and to obtain in the at least one second thinned active region a smaller thickness of the active layer than in the at least one first active region, ∘ at least one part of the thickness of the non-covered part of the insulating trench so as to form an etched part of the insulating trench, ∘ and the entire masking layer, ∘ a part of the thickness of the active layer of the at least one second active region so as to form at least one second thinned active region and to obtain in the at least one second thinned active region a smaller thickness of the active layer than in the at least one first active region, ∘ at least one part of the thickness of the non-covered part of the insulating trench so as to form an etched part of the insulating trench, ∘ and the entire masking layer, - adjusting, after the dry etching step, the height of the surface of the at least one second thinned active region to the height of the surface of said an etched part of the insulating trench, the step of adjusting the height of the surface of the at least one second thinned active region to the height of the surface of said etched part of the insulating trench comprising at least the following steps: - oxidising at least one portion of the second thinned active region so as to form a sacrificial oxide layer; - partially removing the sacrificial oxide layer so as to form a residual sacrificial oxide layer and such that the surface of the residual sacrificial oxide layer is at the same height as the surface of the etched part of the insulating trench.