Shielded gate type metal-oxide-semiconductor field effect transistor and manufacturing method thereof

The invention provides a shielded gate type metal-oxide-semiconductor field effect transistor and a manufacturing method thereof. The manufacturing method comprises the following steps: forming a semiconductor substrate with a trench; forming a sacrificial oxide layer in the trench in an oxidation manner, wherein the sacrificial oxide layer at least covers the side wall of the trench; forming a source polycrystalline region in the trench; forming an insulating oxide layer above the source polycrystalline silicon region in an oxidation manner, so that the source polycrystalline silicon region is completely coated with the sacrificial oxide layer and the insulating oxide layer; filling the trench with polycrystalline silicon through deposition and performing back etching to control the thickness of the insulating oxide layer above the source polycrystalline silicon region; forming a gate oxide layer in the trench in an oxidation manner, wherein the gate oxide layer at least covers the side wall of the trench; f