Structure and fabrication method of electrostatic discharge protection circuit
AssigneeUnited Microelectronics Corp.
InventorsShiao-Shien Chen, Tsun-Lai Hsu, Tien-Hao Tang, Hua-Chou Tseng
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Abstract
A structure of an electrostatic discharge protection circuit, in which a buried layer is formed in the substrate of the electrostatic discharge protection circuit, and a sinker layer electrically connected to the buried layer and a drain is also formed therein. Thereby, when the electrostatic discharge protection circuit is activated, the current flows from a source through the buried layer and the sinker layer to the drain. The current flow path is remote from the gate dielectric layer to avoid damaging the gate dielectric by a large current, so as to improve the dielectric strength of the electrostatic discharge protection circuit.
Claims11
A method for fabricating an electrostatic discharge protection circuit, comprising:
- providing a substrate;
- forming a well in the substrate, wherein the well is doped with a first conductive type;
- forming a buried layer at a lateral junction between the well and the substrate, wherein the buried layer is doped with a second conductive type;
- forming a sinker layer doped with the second conductive type in the well, wherein the sinker layer is electrically connected to the buried layer;
- forming a gate on the well;
- forming a source and a drain in the well at two sides of the gate, wherein the gate and the source/drain constitute an electrostatic discharge (ESD) transistor, and the drain is directly connected to the sinker layer, such that the sinker layer electrically connects the buried layer with the drain of the transistor and an ESD current flows from the source through the well, the buried layer and the sinker layer to the drain;
- and
- forming a substrate-connecting region in the well.
Dependencies are inferred from the claim text.