Semiconductor devices and methods of manufacturing semiconductor device

A method for manufacturing a semiconductor device, comprising:

• providing a silicon carbide epitaxial layer, wherein a p-type well region, a heavily doped n-type region on a surface of the p-type well region, and a heavily doped p-type region below the heavily doped n-type region and within the p-type well region are predefined in the silicon carbide epitaxial layer;
• forming a first gate trench passing through the p-type well region in the silicon carbide epitaxial layer;
• forming a first deeply doped p-type region within the silicon carbide epitaxial layer below the first gate trench, wherein a width of the first deeply doped p-type region is narrower than a width of the first gate trench;
• forming a gate oxide layer on a bottom surface and side surfaces of the first gate trench and on the heavily doped n-type region;
• forming a polysilicon layer on the gate oxide layer;
• forming an interlayer dielectric layer on the polysilicon layer;
• and
• forming a source trench passing through the interlayer dielectric layer and the gate oxide layer and extending into the heavily doped n-type region and the heavily doped p-type region.