Electrostatic discharge protection device for integrated circuits and its method for fabrication

A method for fabricating an electrostatic discharge protection device, comprising:

• providing a semiconductor substrate;
• forming a field oxide layer on said substrate;
• forming a diffusion barrier on said substrate not covered by said field oxide layer;
• forming two openings through said diffusion barrier on opposite sides of said field oxide layer;
• forming a polysilicon layer on said barrier layer to contact said substrate via said openings, wherein said polysilicon layer is doped with impurities;
• diffusing said impurities, into said substrate to form two lightly-doped regions under said openings, respectively;
• patterning said polysilicon layer to form two conducting blocks on said lightly-doped regions, respectively;
• implanting ions into said substrate not covered by said field oxide layer and said conducting blocks to form heavily-doped regions, which have junction depths less than that of said lightly-doped regions;
• forming a dielectric layer overlying the overall surface of said device;
• forming two contact windows through said dielectric layer, each window exposing one of said conducting blocks;
• and
• forming two electrodes, each electrode connected to one of said conducting blocks via a respective one of said contact windows.