ABSTRACT
Primary responses to be considered during process optimization for copper electroplating of integrated circuits interconnects include filling performance, within die uniformity, within wafer uniformity, grain size, copper electromigration behavior, defects in the deposited film, and defects in the circuitry following chemical mechanical polishing (CMP). In damascene electroplating this is known as the terminal effect and will be described in greater detail in the section covering damascene plating thickness distribution control. Although chloride ions are considered to be part of the electrolyte, the primary requirement for their addition to solution is based on interactions with the organic additives required to achieve desired metallurgy and fill performance. In damascene applications, levelers are added to the plating bath primarily to reduce the rapid copper growth over features which have undergone bottom-up fill, and thus improve the planarity of the film for subsequent CMP processing.
