Abstract: An ESD protection structure includes a first conductive type substrate; first and second well regions of a first conductive type; a third well region of a second conductive type located between the first and second well regions; a first doped region of the first conductive type and a second doped region of the second conductive type disposed in the first well region; a third doped region of the first conductive type and a fourth doped region of the second conductive type disposed in the second well region; and fifth and sixth doped regions disposed at an interface of the first and third well regions or an interface of the second and third well regions. The fifth doped region of the first conductive type is located in the first or second well region, and the sixth doped region of the second conductive type is located in the third well region.