The invention discloses a
semiconductor structure and a manufacturing method thereof. The manufacturing method comprises the steps of forming a substrate including a first region and a second region and fin portions protruding out of the substrate; forming a first pseudo gate structure at the surface of the fin portion in the first region, wherein the first pseudo gate structure comprises a
gate oxide layer and a first pseudo gate
electrode layer; forming a second pseudo gate structure at the surface of the fin portion in the second region, wherein the second pseudo gate structure comprises a
gate oxide layer and a second pseudo gate
electrode layer; forming a
dielectric layer; removing the first pseudo gate
electrode layer, and forming a first opening in the
dielectric layer; forming a compensation side wall at the side wall of the first opening; removing the second pseudo gate structure, and forming a second opening in the
dielectric layer; forming a
gate dielectric layer at the surface of the
gate oxide layer, the side wall of the compensation side wall and the bottom and the side wall of the second opening; and filling a
metal layer in the first opening and the second opening. The compensation side wall covers a damaged part of the gate
oxide layer, so that the damaged part of the gate
oxide layer is enabled to become a non-effective gate
oxide layer above a channel region, and thus the electrical property of the device is improved.