Patent ID: 8878343

Claim:
A field effect semiconductor device, comprising: a semiconductor body, comprising: a main horizontal surface and a first semiconductor region of a first conductivity type; a second semiconductor region of a second conductivity type arranged between the first semiconductor region and the main horizontal surface, the first semiconductor region and the second semiconductor region forming a pn-junction; an insulating layer arranged on the main horizontal surface; a first metallization arranged on the insulating layer; a deep trench extending from the main horizontal surface vertically below the pn-junction, the deep trench comprising a conductive region insulated from the first semiconductor region and the second semiconductor region; a narrow trench comprising a polycrystalline semiconductor region extending from the first metallization, through the insulating layer and at least to the conductive region; and a vertical poly-diode structure comprising a horizontally extending pn-junction, the vertical poly-diode structure being arranged at least partly in the narrow trench.