Silicon carbide mosfet transistor device with improved characteristics and corresponding manufacturing process

A MOSFET transistor device, comprising:

• forming a functional layer of silicon carbide, having a first conductivity type;
• gate structures formed on a top surface of said functional layer, each of the gate structures including a dielectric region and an electrode region;
• body wells having a second conductivity type, formed within said functional layer, the body wells separated from one another by surface-separation regions of said functional layer;
• source regions having said first conductivity type, the source regions formed within said body wells, laterally and partially underneath respective gate structures;
• and
• modified-doping regions, arranged in the surface-separation regions of said functional layer, underneath respective gate structures, said modified-doping regions having a modified concentration of dopant as compared to the concentration of the functional layer, wherein the modified doping regions include a stack of a respective top layer and a respective bottom layer underlying the top layer, wherein the bottom layer has a higher dopant concentration than the functional layer and the top layer has a lower dopant concentration with respect to the bottom layer.

A process for manufacturing a MOSFET transistor device, comprising:

• forming a functional layer of silicon carbide, having a first conductivity type;
• forming gate structures on a top surface of said functional layer, each of the gate structures including a dielectric region and an electrode region;
• forming body wells having a second conductivity type, within said functional layer, the body wells separated from one another by surface-separation regions of said functional layer;
• forming source regions having said first conductivity type, within said body wells, laterally and partially underneath respective gate structures;
• and
• forming modified-doping regions, arranged in the surface-separation regions of said functional layer, underneath respective gate structures, said modified-doping regions having a modified concentration of dopant as compared to the concentration of the functional layer, wherein said modified-doping regions extend transversally throughout an entire width of the respective surface-separation regions, terminating at the body wells.