Capacitive microelectromechanical pressure transducer and related manufacturing process

A process for manufacturing a MEMS pressure transducer, comprising:

• forming a semiconductor body;
• forming a fixed electrode region arranged above the semiconductor body;
• and
• forming a membrane suspended above the fixed electrode region to delimit a cavity, the membrane being deformable as a function of pressure and forming a variable capacitor together with the fixed electrode region;
• and
• wherein forming the membrane comprises:
• forming a lower conductive region made of polysilicon which delimits an upper boundary of the cavity and is traversed by one or more holes which face the cavity, the lower conductive region being impermeable to gases, except for the one or more holes;
• forming an intermediate structure made of polysilicon permeable to gases which closes said one or more holes;
• and
• forming an upper conductive region made of polysilicon or amorphous silicon which extends on the intermediate structure and the lower conductive region, said upper conductive region being impermeable to gases;
• wherein the membrane is laterally delimited by a lateral surface formed by the lower conductive region and the upper conductive region;
• and
• wherein the intermediate structure does not face the lateral surface of the membrane.