Method for producing a structure comprising at least one active part having zones of different thicknesses

A method for producing a structure comprising an active part comprising at least one first suspended zone and a second suspended zone of different thicknesses from a first substrate, said first substrate comprising a first face made of monocrystalline semi-conductor material, called a front face, and a second face opposite to the first face, called a rear face, said method comprising the following steps:

• a) machining the front face of the first substrate to define the lateral contours of at least one first suspended zone made of monocrystalline semi-conductor material according to a first thickness less than that of the first substrate, and passivating said lateral contours;
• b) forming a stop layer of etching of the first suspended zone between said first suspended zone and the rear face;
• c) forming on the front face of the first substrate a sacrificial layer selective to the etching with respect to the semi-conductor material of the first substrate;
• d) machining from the rear face of the first substrate up to releasing certain zones of said sacrificial layer to form at least one second suspended zone and to make it possible to reach the stop layer of the first suspended zone;
• e) releasing the first and second suspended zones.