Semiconductor device and forming method thereof

The invention discloses a semiconductor device and a forming method thereof. The method comprises the steps of forming a first groove and a second groove in a first mask layer; forming a barrier layeron the first mask layer, in a partial region of the first groove and in a partial region of the second groove, wherein the barrier layer is provided with a first barrier opening located in a partialregion of the first groove and a second barrier opening located in a partial region of the second groove, the first barrier opening and the second barrier opening are separated, the first barrier opening is communicated with the first groove, the second barrier opening is communicated with the second groove, and the size of the second barrier opening in the first direction is larger than that of the first barrier opening in the first direction; forming a first segmentation layer in the first barrier opening, wherein the first segmentation layer segments the first groove in a first direction; forming second segmentation