Ldmos power semiconductor device and manufacturing method of the same

A method for manufacturing an electronic semiconductor device, comprising:

• defining a first structural region having a first conductivity in a substrate, the first structural region including a first side and a second side;
• forming, on the first side of the first structural region, a second structural region having a first side exposed and having a second conductivity opposite to the first conductivity;
• forming a body region, having the second conductivity, in the second structural region at the first side of the second structural region;
• forming a source region, having the first conductivity, within the body region and facing the first side of the second structural region;
• forming a drain region, having the first conductivity, facing the first side of the second structural region;
• and
• forming a gate electrode on the first side of the structural region, between the source region and the drain region,
• removing selective portions of the second structural region so as to form a through hole, which extends through the second structural region throughout a thickness of the second structural region;
• removing selective portions of the first structural region exposed through said through hole so as to form a first trench, which extends through the second structural region;
• forming a trench dielectric region inside the first trench;
• forming a first trench conductive region inside the trench dielectric region;
• removing selective portions of the second structural region in the body region so as to form a second trench;
• forming a second trench conductive region inside the second trench so that the second trench conductive region is in electrical contact with the body region and with the source region;
• and
• electrically coupling together said first and second trench conductive regions,
• wherein forming the drain region includes forming the drain region between, and in direct contact with, the body region and the trench dielectric region and extending in depth through the second structural region coming into electrical contact with, the first structural region.

An electronic semiconductor device comprising:

• a bridge of first and second transistors in a semiconductor body having a first side and a second side opposite to one another along a first direction and including a first structural region that faces the second side and has a first conductivity, wherein the first transistor includes:
• a second structural region which extends over the first structural region, faces the first side, and has a second conductivity opposite to the first conductivity;
• a first body region having the second conductivity and extending in the second structural region at the first side;
• a first source region having the first conductivity, extending within the first body region and facing the first side;
• a first drain region having the first conductivity and facing the first side of the semiconductor body;
• a first gate electrode extending over a portion of the first side of the semiconductor body between the first source region and the first drain region;
• a first trench which extends through the second structural region and houses a trench dielectric region and a first trench conductive region;
• and
• a second trench which extends through part of the second structural region inside the first body region, said second trench housing a second trench conductive region in electrical contact with the first body region and with the first source region,
• wherein the first drain region extends through the second structural region, electrically contacts the first structural region, and is arranged between, and in direct contact with, the first body region and the trench dielectric region, said first and second trench conductive regions being electrically coupled to one another.