Transistor device with high current robustness

A transistor device that can be operated in an on-state and an off-state, comprising:

• a first emitter region of a first doping type, a second emitter region of a second doping type, a body region of the second doping type, a drift region of the first doping type, a field-stop region of the first doping type, and at least one boost structure;
• and
• a gate electrode dielectrically insulated from the body region by a gate dielectric,
• wherein the body region is arranged between the first emitter region and the drift region, the field-stop region is arranged between the drift region and the boost structure, and the boost structure is arranged between the field-stop region and the second emitter region,
• wherein the at least one boost structure comprises a base region of the first doping type and at least one auxiliary emitter region of the second doping type separated from the second emitter region by the base region,
• wherein a doping profile of the drift region and the field-stop region is such that in the off-state of the transistor device an electric field associated with applying a load path voltage between the first emitter region and the second emitter region stops in the field-stop region spaced apart from the at least one auxiliary emitter region when a critical field strength is reached at a pn junction between the body region and the drift region.