Semiconductor device having a group of trenches in an active region and a mesa portion

A semiconductor device comprising:

• a first semiconductor region with first conductivity type;
• a second semiconductor region with second conductivity type positioned above the first semiconductor region;
• a third semiconductor region with the first conductivity type positioned above the second semiconductor region;
• a main electrode electrically coupled to the first semiconductor region and the second semiconductor region;
• and
• a group of trenches positioned in an active region inside the first semiconductor region, each trench comprising
• an insulator positioned inside the trench,
• a gate electrode positioned at an upper part in the insulator, and
• a first field plate positioned at a lower part in the insulator;
• a first trench positioned in an outer peripheral region on an outer side of the active region;
• a second trench positioned on an outer side of the first trench positioned in the outer peripheral region on the outer side of the active region;
• a mesa portion positioned between the first and the second trenches;
• a first insulating layer positioned inside the first trench;
• a second insulating layer positioned inside the second trench;
• a second field plate positioned inside the first insulating layer in the first trench;
• and
• a third field plate positioned inside the second insulating layer in the second trench, wherein
• the mesa portion comprises another second semiconductor region with the second conductivity type electrically coupled to the main electrode on an outermost side, and
• the first trench does not have the gate electrode at upper part of the first trench.