Abstract: Semiconductor structures and methods for manufacturing the same are provided. The method for manufacturing the semiconductor structure includes forming a fin structure protruding from a substrate, and the fin structure includes first semiconductor material layers and second semiconductor material layers alternately stacked. The method also includes forming a dummy gate structure across the fin structure and forming a gate spacer on a sidewall of the dummy gate structure. The method also includes partially oxidizing the gate spacer to form an oxide layer and removing the oxide layer to form a modified gate spacer. The method also includes removing the first semiconductor material layers to form gaps and forming a gate structure in the gaps to wrap around the second semiconductor material layers and over the second semiconductor material layers to cover the modified gate spacer.