Power semiconductor with polysilicon structure at bottom of trench and method for manufacturing same

The invention relates to a power semiconductor with a polysilicon structure at the bottom of a trench and a method for manufacturing the same. The power semiconductor comprises a first conduction type substrate, the trench, a heavy-doping polysilicon structure, a gate polysilicon structure and a gate dielectric layer, wherein the trench is formed inside the substrate; the heavy-doping polysilicon structure is positioned at a lower part of the trench, and at least one side edge of the heavy-doping polysilicon structure is in direct contact with the substrate; the gate polysilicon structure is positioned at an upper part of the trench; the gate dielectric layer is positioned between the gate polysilicon structure and the heavy-doping polysilicon structure; and the doping of the heavy-doping polysilicon structure diffuses outwardly to form a heavy-doping region.