VDMOS device and manufacturing method therefor

A method for manufacturing a VDMOS device, comprising:

• forming a trench in a semiconductor substrate, the trench including a first trench region, a second trench region, a third trench region, and a fourth trench region communicating the first trench region and the second trench region, and a fifth trench region communicating the second trench region and the third trench region;
• wherein a width of the second trench region is greater than a width of the first trench region, a width of the first trench region is greater than widths of the third trench region, the fourth trench region, and the fifth trench region;
• forming a first insulating layer on the semiconductor substrate, the first insulating layer filling up the third trench region and the fifth trench region, and being attached to sidewalls of the first trench region, the second trench region, and the fourth trench region;
• forming a first polysilicon layer on the first insulating layer, the first polysilicon layer filling up the first trench region, being attached to a sidewall of the first insulating layer in the second trench region, and the first polysilicon layer in the first trench region being connected to the first polysilicon layer in the second trench region;
• forming a second insulating layer on the first polysilicon layer, the second insulating layer filling up the second trench region;
• removing a portion of the second insulating layer until the first polysilicon layer being exposed;
• removing a portion of the first polysilicon layer, a remaining first polysilicon layer forming a first electrode;
• forming a third insulating layer on the semiconductor substrate, the third insulating layer filling up the first trench region, the second trench region, and the fourth trench region;
• removing portions of the third insulating layer, the second insulating layer, and the first insulating layer such that a top of the first polysilicon layer being higher than tops of the first insulating layer and the second insulating layer;
• forming a gate oxide layer on the semiconductor substrate;
• forming a second polysilicon layer on the gate oxide layer, and the second polysilicon layer filling up the trench;
• and
• removing a portion of the second polysilicon layer, exposing the gate oxide layer on the surface of the semiconductor substrate and the top of the second insulating layer, and the remaining second polysilicon layer forming a second electrode.