- ESD PROTECTION CIRCUIT OF SEMICONDUCTOR CONTROLLED RECTIFIER STRUCTURE CAPABLE OF OPERATING AT LOW TRIGGER VOLTAGE

摘要

PURPOSE: An electrostatic discharge protection circuit having a structure of a semiconductor-controlled rectifier operated under a lower trigger voltage is provided to perform a protective function for an electrostatic discharge function by using the semiconductor-controlled rectifier. CONSTITUTION: The second conductive type well region(102) is formed on the first conductive type semiconductor substrate(101). The first to the third doped regions(103,104,105) are formed on the well region(102). The first doped region(102) is located between the second and the third doped regions(104,105). The first and the second doped regions(103,104) are electrically connected with a pad(106). The fourth doped region(107) is formed on the semiconductor substrate(101). The fifth doped region(108) is formed on the semiconductor substrate(101). The fourth and the fifth doped regions(107,108) are electrically connected with a ground voltage terminal(109). A switch circuit(110) is connected between the third doped region(105) and the ground voltage terminal(109). A plurality of NMOS transistors(M1 to Mi) are connected between the third doped region(105) and the ground voltage terminal(109).