Power metal oxide semiconductor field-effect transistor and manufacturing method thereof

The invention discloses a power metal oxide semiconductor field-effect transistor, which comprises a substrate, an epitaxial layer, a first trench, a second trench, a first well region, a second well region and a source region. The epitaxial layer is arranged above the substrate and is provided with a first conductive type dopant. The first trench extends downwards from a first region on the upper surface of the epitaxial layer; and the second trench extends downwards from the bottom of the first trench. The width of the second trench is less than the width of the first trench. The second well region and the first well region are separated from each other. The first well region is arranged on the bottom of the first trench and the bottom of the second trench and is provided with a second conductive type dopant. The second well region extends downwards from a second region on the upper surface and is also provided with a second conductive type dopant. The source region is arranged in the first well region and