Semiconductor isolation structure and manufacturing method thereof

The invention provides a semiconductor isolation structure and a manufacturing method thereof. According to the manufacturing method, a plurality of grooves are formed in the semiconductor substrate,then a pull-back process is executed to enable the side walls of a pad oxide layer and a hard mask layer on the semiconductor substrate to shrink inwards, the grooves are filled with the first isolation dielectric layer, and then an ion implantation process is executed to enable the upper portion of the first isolation dielectric layer to form a modified area. The depth of the modified area is greater than or equal to the total thickness of the pad oxide layer and the hard mask layer, a part of the first isolation dielectric layer in the modified area is removed by soaking with an etching solution, holes in the first isolation dielectric layer are opened or even removed, and the second isolation dielectric layer is filled in the grooves, so that the holes in the isolation dielectric in thegrooves can be reduced, a