Fabrication method for a deep trench isolation structure of a high-voltage device

摘要

A fabrication method for a semiconductor device. On a semiconductor silicon substrate with a first type conductivity, an epitaxial layer with a second type conductivity and an oxide layer on the epitaxial layer are formed with at least a deep trench. Ion implantation is used to form an ion diffusion region with the first type conductivity which is formed in the epitaxial layer and surrounds the sidewall and bottom of the deep trench. An oxide liner is formed on the sidewall and bottom of the deep trench, and then an undoped polysilicon layer is formed to fill the deep trench. The combination of the ion diffusion region and the undoped polysilicon layer serves as a deep trench isolation structure.