Transitional dielectric layer to improve reliability and performance of high dielectric constant transistors

Abstract

A gate dielectric structure () fabrication process includes forming a transitional dielectric film () overlying a silicon oxide film (). A high dielectric constant film () is then formed overlying an upper surface of the transitional dielectric film (). The composition of the transitional dielectric film () at the silicon oxide film () interface primarily comprises silicon and oxygen. The high K dielectric () and the composition of the transitional dielectric film () near the upper surface primarily comprise a metal element and oxygen. Forming the transitional dielectric film () may include forming a plurality of transitional dielectric layers () where the composition of each successive transitional dielectric layer () has a higher concentration of the metal element and a lower concentration of silicon. Forming the transitional dielectric layer () may include performing multiple cycles of an atomic layer deposition process () where a precursor concentration for each cycle differs from the precursor concentration of the preceding cycle.