A ferroelectric semiconductor device and method are described herein. The method includes performing a diffusion anneal process to drive elements of a dopant film through an amorphous silicon layer and into a gate dielectric layer over a fin to form a doped gate dielectric layer with a gradient depth profile of dopant concentrations. The doped gate dielectric layer is crystallized during a post-cap anneal process to form a gradient depth profile of ferroelectric properties within the crystallized gate dielectric layer. A metal gate electrode is formed over the crystallized gate dielectric layer to obtain a ferroelectric transistor with multi-ferroelectric properties between the gate electrode and the channel. The ferroelectric transistor may be used in deep neural network (DNN) applications.