A novel vertical field plate (VFP) structure with low specific on-resistance (Ron,sp) is proposed. The VFP is inserted in the field oxide of the drift region with heavily doped N pillar parallel to the trench oxide layer (TOL), which depletes fully the drift region to decrease Ron,sp effectively and enhances the bulk field (ENBULF). The VFP optimises the bulk electric field to increase the breakdown voltage (BV). The BV of VFP is 668 V with an Ron,sp of 44.7 mΩ cm2, which is much lower than the silicon limit.