The present invention provides a method for manufacturing a semiconductor structure, which comprises: providing an SOI substrate, forming a gate structure on the SOI substrate; etching an SOI layer of the SOI substrate and a BOX layer of the SOI substrate on both sides of the gate structure to form trenches, the trenches exposing the BOX layer and extending partly into the BOX layer; forming sidewall spacers on sidewalls of the trenches; forming inside the trenches a metal layer covering the sidewall spacers, wherein the metal layer is in contact with the SOI layer which is under the gate structure. Accordingly, the present invention further provides a semiconductor structure formed according to aforesaid method. The manufacturing method and the semiconductor structure according to the present invention make it possible to reduce capacitance between a metal layer and a body silicon layer of an SOI substrate when a semiconductor device is in operation, which is therefore favorable for enhancing performance of the semiconductor device.