Method for manufacturing a low-noise electroacoustic transducer

A method for manufacturing an electroacoustic transducer comprising:

• a frame;
• an element movable relative to the frame, the movable element comprising a membrane and a membrane rigidifying structure;
• a first transmission arm, the movable element being coupled to one end of the first transmission arm;
• the method comprising:
• forming a first sacrificial layer on a substrate, the first sacrificial layer comprising a first portion and a second portion adjacent to the first portion, the first portion having a greater thickness than the second portion;
• forming a first structural layer on the first sacrificial layer;
• forming a second sacrificial layer on the first structural layer;
• forming a second structural layer on the first structural layer and on the second sacrificial layer;
• etching the second structural layer so as to expose the second sacrificial layer and to delimit the rigidifying structure of the movable element;
• etching the first structural layer up to the first sacrificial layer so as to delimit the membrane of the movable element, a peripheral portion of the membrane being arranged facing the first portion of the first sacrificial layer;
• etching the second sacrificial layer so as to expose a first face of the membrane;
• etching the substrate so as to delimit the first transmission arm, the first sacrificial layer acting as a stop layer to etching of the substrate;
• and
• etching the first sacrificial layer so as to expose a second, opposite face of the membrane.