A planar integrated MEMS device has a piezoelectric element on a dielectric isolation layer over a flexible element attached to a proof mass. The piezoelectric element contains a ferroelectric element with a perovskite structure formed over an isolation dielectric. At least two electrodes are formed on the ferroelectric element. An upper hydrogen barrier is formed over the piezoelectric element. Front side singulation trenches are formed at a periphery of the MEMS device extending into the semiconductor substrate. A DRIE process removes material from the bottom side of the substrate to form the flexible element, removes material from the substrate under the front side singulation trenches, and forms the proof mass from substrate material. The piezoelectric element overlaps the flexible element.