Semiconductor structure and forming method thereof

The invention provides a semiconductor structure and a forming method thereof. The semiconductor structure comprises a semiconductor substrate, a gate dielectric layer and a metal gate which are sequentially located on the semiconductor substrate, an aluminum oxide barrier layer positioned at the bottom and two sides of the metal gate, an aluminum film positioned at the bottom and the side wall of the aluminum oxide barrier layer, and side walls positioned on the two sides of the gate dielectric layer and the aluminum film. According to the semiconductor structure and the forming method thereof, the preparation method is simple, the production efficiency can be improved, the particle defect of a product is reduced, and the threshold voltage of the gate can be controlled by controlling the thickness of the aluminum film. 本申请提供半导体结构及其形成方法，所述半导体结构包括：半导体衬底；依次位于所述半导体衬底上的栅介电层、金属栅极；位于所述金属栅极底部和两侧的氧化铝阻挡层；位于所述氧化铝阻挡层底部和侧壁的铝膜；以及位于所述栅介电层和所述铝膜两侧的侧墙。本申请所述的半导体结构及其形成方法，制备方法简单，可以提高生产效率，减少产品颗粒缺陷，并且可以通过控制所述铝膜的厚度来控制栅极阈值电压。