Provided is a semiconductor device including: a plurality of trench portions which are provided to positions below a base region from an upper surface of a semiconductor substrate and are arranged next to one another in a first direction on the upper surface of the semiconductor substrate; a first lower end region of a second conductivity type, which is arranged at a first depth position and is provided in contact with a lower end of two or more of the trench portions; and a second lower end region which is arranged at the first depth position and is arranged at a position not overlapping with the first lower end region, in which the second lower end region includes at least one of a region of a first conductivity type or a region of a second conductivity type which has a lower doping concentration than the first lower end region.

The present disclosure provides embodiments of semiconductor structures. A semiconductor structure according to the present disclosure includes a substrate, a fin-shaped structure disposed over the substrate, the fin-shaped structure including a plurality of first semiconductor layers interleaved by a plurality of second semiconductor layers, a gate structure disposed over a channel region of the fin-shaped structure, a first source/drain feature extending through at least a first portion the fin-shaped structure, a second source/drain feature extending through at least a second portion of the fin-shaped structure, and a backside metal line disposed below the substrate and spaced apart from the first source/drain feature and the second source/drain feature.

In one aspect, a silicon-on-insulator semiconductor device includes: a substrate; a buried dielectric layer disposed on the substrate; a first electrode; a second electrode; and a drift region disposed on the buried dielectric layer. An upper surface of the drift region forms a drop structure including a first side adjacent to the first electrode, a second side adjacent to the second electrode, and a transition region between the first side and the second side. An upper surface of the second side is higher than a bottom surface of the first side, such that a thickness of the drift region at the second side is greater than that at the first side. The first electrode and the second electrode are configured such that a voltage applied to the second electrode is greater than a voltage applied to the first electrode when a reverse bias voltage is applied to the device.

Provided is a semiconductor device including: a semiconductor substrate having an upper surface and a lower surface and provided with a drift region of a first conductivity type; and a buffer region provided between the drift region and the lower surface and having a higher doping concentration than the drift region. The buffer region has M doping concentration peaks provided at different positions in a depth direction of the semiconductor substrate, and a charge carrier coefficient represented by Expression (1) is 2000 or more and 50000 or less in at least one integer i (i is an integer of 1 or more and M1 or less).