MEMS device comprising an insulated suspended diaphragm, in particular pressure sensor, and manufacturing process thereof

A device, comprising:

• a semiconductor body including:
• a first main face;
• and
• a second main face opposite to the first main face;
• a substrate including a conductivity type;
• and
• a first conductive region extending into the substrate from the first main face, the first conductive region having the conductivity type;
• an access trench extending into the first main face of the semiconductor body;
• a plug region fills the access trench and closes off the access trench;
• a buried cavity is within the semiconductor body, the buried cavity is fully enclosed and is within the semiconductor body;
• and
• a diaphragm overlaps the buried cavity and is between the first main face and the buried cavity, the diaphragm having a buried face facing the buried cavity, and wherein:
• the substrate having a first doping level;
• the first conductive region having a second doping level higher than the first doping level, the first conductive region accommodates the diaphragm and extends along the buried cavity;
• and
• the semiconductor body further includes a second conductive region extending into the substrate from the second main face, having the conductivity type, and having a third doping level higher than the first doping level.

A device, comprising:

• a substrate including a first main face and a second main face opposite to the first main face and one or more conductive regions between the first main face and the second main face, the substrate has a conductivity type, and the conductive type is an N-type, and the one or more conductive regions includes:
• a first conductive region at the first main face having a N+ type doping;
• a second conductive region at the second main face having the N+ type doping;
• and
• a third conductive region extending from the first conductive region to the second conductive region, the third conductive region having an N-type doping;
• a buried cavity in a respective conductive region of the one or more conductive regions of the substrate;
• a diaphragm extending between the buried cavity and the first main face of the substrate, the diaphragm having a buried face facing the buried cavity;
• a diaphragm insulating layer extending on the buried face of the diaphragm;
• and
• a lateral insulating region of insulating material, extending into the substrate along a closed line, between the first main face and the diaphragm insulating layer, above the buried cavity, the lateral insulating region laterally delimiting the diaphragm and being in contact with the diaphragm insulating layer.