Method of Fabricating An Electromechanical Structure Including at Least One Mechanical Reinforcing Pillar

A method of fabricating an electromechanical structure presenting a first substrate (1) including at least one layer (1′) of monocrystalline material, said layer being covered with a sacrificial layer made of sacrificial material, the sacrificial layer presenting a free surface, the structure presenting at least one mechanical reinforcing pillar received in said sacrificial layer, wherein the method comprises:

• a) making at least one well region (51, 52) in the sacrificial layer (2) by etching at least in the entire thickness of the sacrificial layer (2), the well region defining at least one said mechanical reinforcing pillar;
• b) depositing a first functionalization layer (4, 31, 30) respectively of a first and second functionalization materials, relative to which the sacrificial layer is suitable for being etched selectively, one of the materials being conductive and the other being insulating the first functionalization layer (4) filling at least one well region (51) at least partially and covering the free surface of the sacrificial layer (2) at least around the well region(s);
• b′) depositing a filler layer (6, 32, 40) of a filler material different from the first and second materials for terminating the filling of the well region(s) (51), said filler layer (6) covering the first and/or second functionalization layers (4, 31, 30) at least in part around the well region(s) (51), and planarizing the filler layer (6, 32), such that at least a part of only filler layer (6) is removed, the said at least one mechanical reinforcing pillar being formed and defined by the superposition of at least the first or second functionalization materials and the filler material in the well region(s);
• c) assembly of the first substrate with a second substrate opposite from the first substrate (1) via an assembly surface (4′) of the first substrate, then making at least one through opening formed in the first substrate (1), in order to release the electromechanical structure by removing at least partially the sacrificial layer (2).