Semiconductor device and manufacturing method thereof

A semiconductor device, comprising:

• a substrate;
• an epitaxial layer at a side of the substrate;
• a well region in the epitaxial layer;
• a source region in the well region;
• a base region in the well region and adjacent to the source region;
• a first junction field-effect transistor region adjacent to the well region;
• a second junction field-effect transistor region in the first junction field-effect transistor region, the first junction field-effect transistor region and the second junction field-effect transistor region comprising dopants of a first semiconductor type, wherein a doping concentration of the second junction field-effect transistor region is higher than a doping concentration of the first junction field-effect transistor region, and a bottom of the first junction field-effect transistor region and a bottom of the second junction field-effect transistor region are closer to the substrate than a bottom of the well region is, and the bottom of the first junction field-effect transistor region expands below the bottom of the well region;
• a gate dielectric layer at a side of the epitaxial layer away from the substrate;
• and
• a gate layer at a side of the gate dielectric layer away from the epitaxial layer.