SEMICONDUCTOR DEVICE STRUCTURES AND FABRICATION METHODS THEREOF

A semiconductor device structure and fabrication method thereof are disclosed. The method may include providing a substrate; forming a gate structure on the substrate; forming a spacer structure on the gate structure, and forming a contacting conductive structure on the spacer structure. The spacer structure may cover a side wall of the gate structure, and may include a first spacer layer having a first dielectric constant and a second spacer layer having a second dielectric constant different from the first dielectric constant. The contacting conductive structure may cover a side wall of the spacer structure that is defined by a first side surface of the first spacer layer and a second side surface of the second space. The ratio of the area of the second side surface of the second spacer layer to the total area of the side wall of the spacer structure may be in a range from 78% to 98%.