Abstract: A transistor device includes a semiconductor substrate having a first major surface and transistor cells formed therein. Each transistor cell includes a drift region of a first conductivity type, a body region of an opposing second conductivity type arranged on the drift region, a source region of the first conductivity type arranged on the body region, a columnar field plate trench extending into the first major surface and including a field plate, and a gate trench structure extending into the first major surface and including a gate electrode. A first metallization structure on the first major surface provides a first contact pad for wire bonding. At least one of depth and doping level of the body region is locally increased within the transistor cells located within one or more first areas of the first major surface. One or more of the first areas are located underneath the first contact pad.

Abstract: In an embodiment, a transistor device comprises a semiconductor body comprising a plurality of transistor cells comprising a drift region of a first conductivity type, a body region of a second conductivity type forming a first pn junction with the drift region, the second conductivity type opposing the first conductivity type, a source region of the first conductivity type forming a second pn junction with the body region, a columnar field plate trench extending into a major surface of a semiconductor body and comprising a columnar field plate and a gate trench structure extending into the major surface of the semiconductor body and comprising a gate electrode. At least one of the depth and doping level of the body region locally varies within the transistor cell to improve VGSTH homogeneity within the transistor cell.

Abstract: A substrate having a buffer layer and a barrier layer is formed. The buffer and barrier layers have different bandgaps such that an electrically conductive channel comprising a two-dimensional charge carrier gas arises at an interface between the buffer and barrier layers due to piezoelectric effects. The substrate is placed in a fluorine containing gas mixture that includes free radical state fluorine particles and is substantially devoid of ionic state fluorine particles. A first lateral surface section of the substrate is exposed to the gas mixture such that the free radical state fluorine particles contact the first lateral surface section without penetrating the substrate. A semiconductor device that incorporates first lateral surface section in the structure of the device is formed in the substrate.

Abstract: A substrate having a buffer layer and a barrier layer is formed. The buffer and barrier layers have different bandgaps such that an electrically conductive channel comprising a two-dimensional charge carrier gas arises at an interface between the buffer and barrier layers due to piezoelectric effects. The substrate is placed in a fluorine containing gas mixture that includes free radical state fluorine particles and is substantially devoid of ionic state fluorine particles. A first lateral surface section of the substrate is exposed to the gas mixture such that the free radical state fluorine particles contact the first lateral surface section without penetrating the substrate. A semiconductor device that incorporates first lateral surface section in the structure of the device is formed in the substrate.