Mosfet power device manufactured with reduced number of masks by fabrication simplified processes

Abstract

This invention discloses a semiconductor substrate supports a semiconductor power device. The semiconductor substrate includes a plurality of polysilicon segments disposed over a gate oxide layer including two outermost segments and inner segments wherein each of the inner segments functioning as a gate and the two outermost segments functioning as a field pate and an equal potential ring separated by an oxide-plug gap having an aspect ratio greater or equal to 0.5. Each of the inner segments functioning as a gate having a side wall spacer surrounding edges of the inner segments, and the oxide plug gap being filled with an oxide plug for separating the field plate from the equal potential ring. A plurality of power transistor cells disposed in the substrate for each of the gates covered by an overlying insulation layer having a plurality of contact openings defined therein. A plurality of metal segments covering the overlying insulation layer and being in electric contact with the power transistor cells through the contact openings. A plurality of deep-and-narrow gaps between the metal segments wherein each gap having an aspect ratio equal or greater than 0.5. A passivation layer disposed in the deep-and-narrow gaps between the metal segments having a thickness substantially the same as the metal segments for blocking mobile ions from entering into the power transistor cells.