Electrostatic discharge protective circuit structure and manufacturing method thereof

A buried layer is formed in the substrate of the electrostatic discharge protection circuit and is conncted to the sinker layer. Thus, when the electrostatic discharge protection circuit is activated, the current through a source eletrode feeds to the buried layer, the sinker layer to the drain electrode. Since the current flows through the substrate, thus the current path is far apart from the grid dielectric layer to prevent influence on the grid electrode from large current as well as enhance obdurability of the electrostatic discharge protection circuit.