Insulated gate semiconductor device having trench termination structure and method

A semiconductor device structure, comprising:

• a region of semiconductor material comprising a first conductivity type, a first major surface, a second major surface opposite to the first major, an active region, a termination region, and a transition region interposed between the active region and the termination region;
• active trench structures extending from the first major surface into the region of semiconductor material within the active region, wherein the active trench structures are laterally separated from each other by active mesa regions, wherein the active mesa regions have a first doping concentration of the first conductivity type;
• a termination trench structure extending from the first major surface into the region of semiconductor material within the termination region;
• a transition mesa region interposed between an outermost one of the active trench structures and the termination trench structure, wherein the transition mesa region comprises a second doping concentration of the first conductivity type that is greater than the first doping concentration;
• base regions comprising a second conductivity type opposite to the first conductive type disposed in at least some of the active mesa regions and the transition mesa region adjacent to the first major surface;
• and source regions comprising the first conductivity type disposed in the base regions in the active mesa regions but not in the transition mesa region.

A semiconductor device structure comprising:

• a region of semiconductor material comprising a first conductivity type, an active region, and a termination region;
• a first active trench structure in the active region;
• a second active trench structure in the active region and laterally separated from the first active trench by an active mesa region having a first width, the active mesa region having a first doping concentration of the first conductivity type;
• a first termination trench structure in the termination region and laterally separated from the second active trench by a transition mesa region having a second width and a second doping concentration of the first conductivity type;
• a second termination trench in the termination region and laterally separated from the first termination trench by a first termination mesa region having a third width and a third doping concentration of the first conductivity type;
• a first base region comprising a second conductivity type opposite to the first conductive type in active mesa region;
• a second base region comprising the second conductivity type in the transition mesa region;
• and a third base region comprising the second conductivity type in the first termination mesa region, wherein:
• the second doping concentration is greater than the first doping concentration, wherein:
• the third base region is electrically floating;
• and the first base region and the second base region are electrically connected.