US Patent 7436041 Electrostatic discharge protection circuit using a double-triggered silicon controlling rectifier

An ESD protection circuit using a double-triggered silicon controller rectifier (SCR). The double-triggered silicon controller rectifier (SCR) includes N+ diffusion areas, P+ diffusion areas, a first N-well region, a second N-well region and a third N-well region formed in a P-substrate. The N+ diffusion areas and the P+ diffusion areas are isolated by shallow trench isolation (STI) structures. Two of the N+ diffusion areas are N-type trigger terminals. Two of the P+ diffusion areas are the P-type trigger terminal.