Patent ID: 7675114

Claim:
A trench transistor comprising: trenches formed within a semiconductor body of a first conductivity type along a first direction and adjacent along a second direction, which is perpendicular to the first direction; an insulation layer adjoining the semiconductor body within the trenches; a gate electrode adjoining the insulation layer within the trenches; mesa zones formed between the trenches, said mesa zones having drift zones of the first conductivity type; a body zone formed in the mesa zones above the drift zones, the body zone formed of a second conductivity type opposite to the first conductivity type and with body contact zones of the second conductivity type and source zones of the first conductivity type that extend to a surface of the semiconductor body; and means for forming a breakdown in the mesa zones to increase the avalanche strength below the body contact zones in a depth lying in the region of the trench bottoms; wherein a concentration of dopants for increasing the conductivity of the first conductivity type within the drift zones is greater in a conducting-state region formed from the bottom of the trenches as far as the body zones below the source zones than in a breakdown region formed below the body contact zones.