Field-effect transistor with self-limited current

Abstract

A field-effect transistor is integrated in a chip of semiconductor material of a first type of conductivity, which has a first main surface and a second main surface, opposite to each other. The transistor includes a plurality of body regions of a second type of conductivity, each one extending from the second main surface in the chip. A plurality of drain columns of the second type of conductivity are provided, each one extending from a body region towards the first main surface, at a pre-defined distance from the first main surface. A plurality of drain columns are defined in the chip, each one extending longitudinally between a pair of adjacent drain columns. The transistor includes a plurality of source regions of the first type of conductivity, each one of them extending from the second main surface in a body region; a plurality of channel areas are defined, each one in a body region between a source region of the body region and each drain channel adjacent to the body region. There are then provided a gate terminal extending over the cannel areas (with the gate terminal that is insulated from the second main surface), a source terminal contacting the source regions on the second main surface, and a drain terminal contacting the chip on the first main surface. In the transistor according to an embodiment of the invention, each drain channel includes a first residual portion having a first transversal width and a second prevalent portion having a second transversal width higher than the first transversal width.