The formation of a barrier layer over a high k dielectric layer and deposition of a conducting layer over the barrier layer prevents intermigration between the species of the high k dielectric layer and the conducting layer and prevents oxygen scavenging of the high k dielectric layer. One example of a capacitor stack device provided includes a high k dielectric layer of Ta2O5, a barrier layer of TaON or TiON formed at least in part by a remote plasma process, and a top electrode of TiN. The processes may be conducted at about 300 to 700° C. and are thus useful for low thermal budget applications. Also provided are MIM capacitor constructions and methods in which an insulator layer is formed by remote plasma oxidation of a bottom electrode.