Method to increase silicon nitride tensile stress using nitrogen plasma in-situ treatment and ex-situ uv cure

Abstract

Stress of a silicon nitride layer may be enhanced by deposition at higher temperatures. Employing an apparatus that allows heating of a substrate to substantially greater than 400° C. (for example a heater made from ceramic rather than aluminum), the silicon nitride film as-deposited may exhibit enhanced stress allowing for improved performance of the underlying MOS transistor device. In accordance with alternative embodiments, a deposited silicon nitride film is exposed to curing with ultraviolet (UV) radiation at an elevated temperature, thereby helping remove hydrogen from the film and increasing film stress. In accordance with still other embodiments, a silicon nitride film is formed utilizing an integrated process employing a number of deposition/curing cycles to preserve integrity of the film at the sharp corner of the underlying raised feature. Adhesion between successive layers may be promoted by inclusion of a post-UV cure plasma treatment in each cycle.