A semiconductor electronic device comprising: - a semiconductor body (1, 2), having a first conductivity, delimited by a first side and a second side opposite to one another along an axis; - a body region, having a second conductivity opposite to the first conductivity, in the semiconductor body (1, 2) facing the first side; - a source terminal, having the first conductivity, extending at least in part in the body region; - a drain terminal, having the first conductivity, extending at the second side of the semiconductor body (1, 2); and - a trench gate (6, 14, 16', 24), which extends in the semiconductor body (1, 2) from the first side towards the second side, through the body region and the source region, wherein said trench gate (6, 14, 16', 24) includes a dielectric region of porous silicon oxide buried in the semiconductor body (1, 2), and a gate conductive region extending between the dielectric region of porous silicon oxide and said first side, wherein a gate dielectric extends between the gate conductive region and the semiconductor body (1, 2), characterized in that said trench gate (6, 14, 16', 24), in addition to the gate dielectric, further includes a protection region between the dielectric region of porous silicon oxide and the gate conductive region, designed for separating the dielectric region of porous silicon oxide from the gate conductive region, said protection region being of a dielectric material or of an electrically insulating material, and has a density higher than the density of the dielectric region. - a semiconductor body (1, 2), having a first conductivity, delimited by a first side and a second side opposite to one another along an axis; - a body region, having a second conductivity opposite to the first conductivity, in the semiconductor body (1, 2) facing the first side; - a source terminal, having the first conductivity, extending at least in part in the body region; - a drain terminal, having the first conductivity, extending at the second side of the semiconductor body (1, 2); and - a trench gate (6, 14, 16', 24), which extends in the semiconductor body (1, 2) from the first side towards the second side, through the body region and the source region, wherein said trench gate (6, 14, 16', 24) includes a dielectric region of porous silicon oxide buried in the semiconductor body (1, 2), and a gate conductive region extending between the dielectric region of porous silicon oxide and said first side, wherein a gate dielectric extends between the gate conductive region and the semiconductor body (1, 2), characterized in that said trench gate (6, 14, 16', 24), in addition to the gate dielectric, further includes a protection region between the dielectric region of porous silicon oxide and the gate conductive region, designed for separating the dielectric region of porous silicon oxide from the gate conductive region, said protection region being of a dielectric material or of an electrically insulating material, and has a density higher than the density of the dielectric region. wherein said trench gate (6, 14, 16', 24) includes a dielectric region of porous silicon oxide buried in the semiconductor body (1, 2), and a gate conductive region extending between the dielectric region of porous silicon oxide and said first side, wherein a gate dielectric extends between the gate conductive region and the semiconductor body (1, 2), characterized in that said trench gate (6, 14, 16', 24), in addition to the gate dielectric, further includes a protection region between the dielectric region of porous silicon oxide and the gate conductive region, designed for separating the dielectric region of porous silicon oxide from the gate conductive region, said protection region being of a dielectric material or of an electrically insulating material, and has a density higher than the density of the dielectric region.