A semiconductor structure is disclosed. The semiconductor structure comprises: a substrate (130), a support structure (131), a base region (100), a gate stack, a spacer (240), and a source/drain region, wherein the gate stack is located on the base region (100), and the base region (100) is supported on the substrate (130) by the support structure (131), wherein the sidewall cross-section of the support structure (131) is in a shape of a concave curve; an isolation structure (123) is formed beneath the edges on both sides of the base region (100), wherein a portion of the isolation structure (123) is connected to the substrate (130); a cavity (112) is formed between the isolation structure (123) and the support structure (131); and there exists a source/drain region at least on both sides of the base region (100) and the isolation structure (123). Accordingly, a method for manufacturing the semiconductor structure is also disclosed.