Semiconductor device and manufacturing method thereof

The present disclosure provides a semiconductor device and a manufacturing method thereof. The semiconductor device includes a substrate, a first active region, a second active region, and a gate structure. The first active region and the second active region are disposed in the substrate. The gate structure includes a bottom, a first sidewall attached to the first active region, and a second sidewall attached to the second active region. The first sidewall and the bottom have a first point of intersection, and the first sidewall and a first horizontal line starting from the first point towardthe substrate have a first included angle. The second sidewall and the bottom have a second point of intersection, and the second sidewall and a second horizontal line starting from the second pointtoward the substrate have a second included angle. The first included angle is different from the second included angle. According to the invention, even if the size of the semiconductor device is reduced, the distance between