Method for manufacturing a cmut transducer

A method for manufacturing a CMUT transducer,

• comprising the following steps:
• a) forming a first structure comprising a cavity extending into a first silicon oxide layer coating a face of a first silicon layer;
• b) forming a lower metal electrode of the transducer at the bottom of the cavity;
• c) forming a second structure comprising a second silicon layer;
• and
• d) after steps a), b) and c), transferring and fixing the second structure onto the first structure by molecular bonding, so as to close the cavity,
• wherein the second structure comprises a second silicon oxide layer coating a face of the second silicon layer, and wherein, in step d), the second structure is fixed onto the first structure by molecular bonding of the second silicon oxide layer onto the first silicon oxide layer,
• the method comprising, prior to step d), a step of forming an upper metal electrode of the transducer on and in contact with the face of the second silicon oxide layer opposite to the second silicon layer, and
• the method further comprising, prior to forming the upper metal electrode, a step of forming conductive vias through the second silicon layer, the upper metal electrode of the transducer then being formed in contact with the conductive vias.