Semiconductor structure and forming method thereof

The invention discloses a semiconductor structure and a forming method thereof, and the method comprises the steps: providing a substrate, forming a bottom fin part on the substrate, and forming a channel structure at the top of the bottom fin part; forming an isolation layer on the substrate, wherein the isolation layer covers the side wall of the bottom fin part; forming a sacrificial layer covering the isolation layer and the top of the channel structure; a groove penetrating through the sacrificial layer is formed, the groove stretches across the channel structure and extends towards the two sides of the channel structure, the bottom of the groove is flush with the top of the bottom fin part, and the included angle between the side wall of the groove and the surface of the substrate is a right angle or an obtuse angle; forming a pseudo gate layer in the groove; removing the sacrificial layer; forming an interlayer dielectric layer on the isolation layer at the side part of the pseudo gate layer; removing