Semiconductor device and manufacturing method thereof

A semiconductor device, comprising:

• a substrate;
• a first-type semiconductor layer, which is stacked on the substrate and comprises a channel region extending on an upper surface of the first-type semiconductor layer;
• a second-type doped region, having a doping type which is opposite to that of the first-type semiconductor layer, is located on the first-type semiconductor layer, and at least comprises a first second-type doped region and a second second-type doped region which are separated from the first second-type doped region by the channel region of the first-type semiconductor layer;
• a gate structure located on the channel region of the first-type semiconductor layer,
• wherein an upper surface of the channel region of the first-type semiconductor layer is opposite to a lower surface of the channel region of the first-type semiconductor layer, and the lower surface of the channel region of the first-type semiconductor layer faces the substrate, the channel region of the first-type semiconductor layer has an up-and-down wave shape extending along a width direction of the channel region, so that a distance from a first portion of the upper surface of the channel region of the first-type semiconductor layer to an upper surface of the substrate is greater than a distance from a second portion of the upper surface of the channel region of the first-type semiconductor layer to the upper surface of the substrate.