FABRICATION METHOD FOR SEMICONDUCTOR INTEGRATED CIRCUIT DEVICE

摘要

A method of fabricating a semiconductor integrated circuit device is provided to prevent a decrease of breakdown voltage by protecting a buried oxide layer. A buried oxide layer protecting layer(170a) is formed to bury a trench(132). The buried oxide layer protecting layer on the trench is removed, and a buried oxide layer protecting pattern is formed only underneath the trench. Then, a hard mask pattern(150) is removed through wet etching. Since the buried oxide layer protecting pattern is formed underneath the trench, the buried oxide layer is not exposed when the hard mask pattern is etched, thereby preventing a portion of the buried oxide layer from being etched when etching the hard mask pattern.