A method for forming a capacitor includes providing a metal-containing bottom electrode, forming a capacitor insulator over the metal-containing bottom electrode, forming a metal-containing top electrode over the capacitor insulator, and forming a dielectric-containing field modification layer over the capacitor insulator and at least partially surrounding the metal-containing top electrode. Forming the dielectric-containing field modification layer may include oxidizing a sidewall of the metal-containing field modification layer. A barrier layer may be formed over the capacitor insulator prior to forming the metal-containing top electrode.