Formation of laterally diffused metal-oxide semiconductor device

Abstract

The method of the present invention comprises the following steps. First, a silicon oxide layer is formed on a semiconductor substrate. Then, a first doping N-well region is formed in the semiconductor substrate. Next, a second doping N-well region which overlies the first doping N-well region is formed in the semiconductor substrate. Thereafter, a trench isolation is formed into the semiconductor substrate having a depth less than the depth of the first doping N-well region. Then, the silicon oxide layer is removed. Next, a field oxide is grown on the surface at a bottom of the trench. Then, a third N doping region is formed along the entire surface of the pad oxide layer within the trench. Next, the field oxide layer is removed to expose the semiconductor substrate within the trench. Thereafter, a gate oxide layer is formed onto the surface of a semiconductor layer with the trench. Next, an N-type polysilicon layer is formed to fill the trench. Last, an N,source/drain layer is formed which is located above the second doping N-well region and under the top surface of the semiconductor substrate in order to complete the laterally diffused metal-oxide semiconductor structure.