Semiconductor structure and forming method thereof

The invention discloses a semiconductor structure and a forming method thereof. The semiconductor structure comprises a substrate; the discrete fin parts are positioned on the substrate; the isolating layer is positioned between the fin parts and covers partial side walls of the fin parts; the discrete gate structures are located on the isolation layer and stride across the fin parts, and the source-drain doping structures are located on the fin parts on the two sides of the gate structures; wherein a side wall is arranged between the gate structure and the source-drain doped structure; the interlayer dielectric layer covers the source-drain doping structure; the liner layer covers the interlayer dielectric layer and the gate structure; wherein the gate structure comprises a conductive gate and a gate dielectric layer, a side space is formed between the conductive gate and the side wall, the gate dielectric layer is located at the bottom of the conductive gate and on the side, facing the bottom of the conduct