INPUT PROTECTIVE CIRCUIT DEVICE OF SEMICONDUCTOR INTEGRATED CIRCUIT

摘要

PROBLEM TO BE SOLVED: To sufficiently protect an internal element against excessive input voltage and reduce a circuit area by containing an island region having a reverse conductive type a conductive type to reach the surface of a semiconductor from the interior of a semiconductor layer and a diffused layer of a reverse conductive type to the island region formed in the island region and connected to an input pad. SOLUTION: An input protective circuit device is constituted by forming an epitaxial layer 46 on an N-type semiconductor device 45. A protective circuit 40 is constituted by forming a P-type island region comprising an N+ embedded layer 47, a P embedded layer 49 and a P well 50 sequentially on the N-type semiconductor substrate 45 and an N+ diffused layer 53 in the island region. The N+ diffused layer 53 is narrowed by a field film 55, and an input pad 43 is connected to only the N+ diffused layer 53 via a contact 57. A resistor 41 comprises the field film 55, a nitride film 63 and a polysilicon film 65 on an epitaxial layer 46, in which the N+ embedded layer 47 and an N well 61 are formed sequentially on the N-type semiconductor substrate 45. One end of the polysilicon film 65 is connected to the input pad 43, and the other end is connected to a capacitor 42.