Semiconductor integrated circuit device

摘要

A trench 312a passing through an impurity area 301a of a circuit element formed at a semiconductor layer 306 of an SOI substrate 314 and extending to a conductive layer 311 formed at a semiconductor substrate 304 is provided. Inside the trench 312a, a conductor 310a for electrically connecting the impurity area 301a of the circuit element and the conductive layer 311 is formed. By adopting this structure, it becomes possible to promptly transmit a surge voltage applied through an external connector terminal 101 to the semiconductor substrate 304 to prevent breakdown at the buried insulator layer. Thus, the buried insulator layer in a semiconductor integrated circuit device having an SOI structure is protected by providing a protective element under the impurity area of the integrated circuit element to assure a high degree of reliability while enabling high-speed drive and higher integration.