The invention relates to a
power MOSFET (
Metal-
Oxide -
Semiconductor Field Effect Transistor) device of a novel groove structure and a manufacture method thereof. The unit
cell of the element zone of the
power MOSFET device adopts groove structure; an insulating
oxide layer is arranged in the unit
cell groove; the thickness of a second isolated
gate oxide layer in the unit
cell groove is more thanthe thickness of a first isolated
gate oxide layer; conductive polysilicon is deposited in the cell unit groove; the extending distance of the first conductive polysilicon is more than the extending distance of the second conductive polysilicon in the unit cell groove; the groove mouth of the unit cell groove is covered by an insulating medium layer; a source
electrode contact hole is filled withsecond contract hole filling
metal; the second contract hole filling
metal, a first conductive type filling zone and a second conductive type layer are in
ohmic contact; source
electrode metal is arranged above the unit cell groove; the source
electrode metal and the second
contact hole filling metal are electrically connected; and the first conductive polysilicon, the source electrode metal and the like are in potential connection. The
power MOSFET device has the advantages of low conduction resistance, small grid leak
electric charge Qgd, low switching speed, low switching loss, simple technology and low cost.