Planar DMOS device, preparation method thereof, and electronic device

The invention relates to a planar DMOS device, a preparation method thereof, and an electronic device; and a chip part or all surrounding parts are connected with an extended boron ion implanted region. The invention also relates to the preparation method of the planar DMOS device. While a process condition and chip area are not changed in the invention, an outer ring is designed in a scribing groove so as to enclose or partially enclose the entire chip; movable charges generated in the processing process are eliminated and the concentration of an interface trap is reduced; and when the planar DMOS device is tested on a wafer (silicon wafer) in a normal temperature, the BV (voltage resistance) is stable, and the leakage current is greatly reduced when the high temperature test is carried out.