ELECTROSTATIC DISCHARGE PROTECTION APPARATUS

A semiconductor ESD protection apparatus comprises a substrate; a first doped well disposed in the substrate and having a first conductivity; a first doped area having the first conductivity disposed in the first doped well; a second doped area having a second conductivity disposed in the first doped well; and an epitaxial layer disposed in the substrate, wherein the epitaxial layer has a third doped area with the first conductivity and a fourth doped area with the second conductivity separated from each other. Whereby a first bipolar junction transistor (BJT) equivalent circuit is formed between the first doped area, the first doped well and the third doped area; a second BJT equivalent circuit is formed between the second doped area, the first doped well and the fourth doped area; and the first BJT equivalent circuit and the second BJT equivalent circuit have different majority carriers.