a ferroelectric capacitor includes a bottom electrode , a top electrode , an a ferroelectric layer located between the top and bottom electrodes that extends to completely encapsulate the top electrode , except for a contact hole to allow metalization of the top electrode . the total encapsulation of the top electrode reduces the sensitivity of the ferroelectric capacitor to hydrogen and thus improves electrical switching performance . the encapsulation technique can also be used to improve the performance of ferroelectric transistors and other devices .