Double-groove SGT device with double-layer field plate and preparation method of double-groove SGT device

The invention provides a double-groove SGT device with a double-layer field plate and a preparation method. The double-groove SGT device comprises an N + substrate, a metalized drain electrode, an N-drift region, a metalized source electrode, a shield gate groove, a control gate groove, an N + source region, a P + heavily doped region and a P-type body region, the SGT structure provided by the invention has a double-layer field plate structure, the shape of the whole electric field is closer to a rectangle, and the relationship between on resistance and breakdown voltage is optimized. Meanwhile, the first field plate and the second field plate comprise two kinds of different doped polycrystalline silicon, a formed polycrystalline silicon PN junction introduces a polycrystalline silicon PN junction depletion region capacitor, the polycrystalline silicon PN junction depletion region capacitor is connected with an original output capacitor of the device in series, and the overall output capacitor is reduced. 本发明