A method for forming a semiconductor structure is provided. The method includes following operations. A layer stack is formed over the substrate. The formation of the layer stack includes the following sub-operations: a blocking layer is formed over the substrate, a lower conductive layer is formed over the blocking layer, a first seed layer is formed over the lower conductive layer, a ferroelectric layer is formed over the first seed layer, and an upper conductive layer is formed over the ferroelectric layer. The layer stack is patterned to form a gate stack over the substrate. A spacer layer is formed over sidewalls of the gate stack. A pattered interlayer dielectric layer is formed over the substrate and the gate stack. A source region and a drain region are formed in the substrate through the patterned interlayer dielectric layer.