Semiconductor device

A semiconductor device comprising:

• a semiconductor layer of a first conductivity type having a first main surface on one of opposite sides thereof and a second main surface on the other side thereof;
• an active region disposed in a surface layer of the first main surface of the semiconductor layer;
• an outer region disposed outside the active region in the surface layer of the first main surface of the semiconductor layer;
• a main junction region of a second conductivity type provided in the outer region, the main junction region having an endless shape surrounding the active region as viewed in plan;
• a floating region of the second conductivity type provided in an electrically floating state in the active region;
• a region isolation trench structure which isolates the floating region in the surface layer of the first main surface of the semiconductor layer;
• an outer isolation trench structure disposed in spaced relation from the region isolation trench structure, the main junction region being provided outward of the outer isolation trench structure;
• and
• an intervening region disposed between the region isolation trench structure and the outer isolation trench structure to intervene between the main junction region and the floating region.