Semiconductor device and method of manufacturing the same

A method of manufacturing a semiconductor device, comprising:

• forming an insulated gate electrode structure in a semiconductor substrate of a first conductivity-type;
• forming a base region of a second conductivity-type so as to be in contact with the insulated gate electrode structure at an upper part of the semiconductor substrate;
• forming a first main electrode region of the first conductivity-type so as to be in contact with the insulated gate electrode structure at an upper part of the base region;
• forming an interlayer insulating film on a top surface of the semiconductor substrate;
• opening a contact hole in the interlayer insulating film;
• forming a trench at the upper part of the semiconductor substrate so as to be integrally connected to the contact hole and penetrating the first main electrode region to reach the base region;
• forming a contact region of the second conductivity-type so as to be in contact with a bottom of the trench by implanting impurity ions of the second conductivity-type into the bottom of the trench;
• burying a contact plug in the trench with a barrier metal film interposed;
• and
• forming a second main electrode region on a bottom surface side of the semiconductor substrate,
• the forming the trench is executed so as to have a structure in which an opening width at a lower end of the contact hole conforms to a width at an opening of the trench, an upper part of a side wall continued from the opening of the trench has a curved surface convex to an outside, and a lower part of the side wall continuously connected to the bottom of the trench has a curved surface convex to the outside.