Process metrology of cobalt damascene interconnects

The feasibility of measuring cobalt damascene additives with cyclic voltammetric stripping (CVS) method is demonstrated. 2-Mercapto-5-benzimidazolesulfonic acid (MBIS) and thiourea (TU) were selected as model suppressor and accelerator, respectively, according to published information. Inorganic components such as boric acid also affect the electrochemical properties of electrolytes. This article particularly investigates the effects of boric acid on the reduction processes in cobalt baths. The effect of dissolved oxygen on CVS is also studied.