Semiconductor device and forming method thereof

The invention provides a semiconductor device and a forming method thereof. The forming method of the semiconductor device comprises the following steps: providing a semiconductor substrate; removing the first barrier layer and a part of the gate layer of the first gate structure to enable the top surface of the gate layer in the first region to be lower than the top surface of the gate layer in the second region; forming stress epitaxial layers in the semiconductor substrate at two sides of the second gate structure; and forming a metal silicide layer on the surface of the gate layer in the first region and the surface of the stress epitaxial layer. According to the semiconductor device and the forming method thereof provided by the invention, the height of the gate layer in the first region is reduced before the grinding process, so the height of the gate layer in the first region is lower than that of the gate layer in the second region, and the metal silicide layer in the first region cannot be ground in