Method for making at least one first suspended part of a microelectronic or nanoelectronic structure from a monolithic part of a first substrate, the method comprising the following steps: make a first etching with a first given depth in the monolithic substrate to define the suspended part, deposit a protective layer on at least the side edges of the first etching, make a second etching with a second depth in the first etching, make a physicochemical treatment of at least part of the zone located under the suspended structure so as to modify it, and release the suspended part by removal of the physicochemically treated part.