Interconnection failure caused by bath degradation in copper electroplating and its VM-FDC using mathematical model

This paper describes a copper interconnection failure in a damascene process of a system on chip (SoC) caused by the plating bath degradation in copper electroplating equipment. By ldquosemimetricsrdquo using EES (Equipment Engineering System) data for many variables in the equipment and some statistical methods, it is clarified that the root cause of the interconnection failure is the plating bath degradation. The degradation means the increase of a by-product, whose existence is confirmed by analyzing the bath plating using HPLC (high performance liquid-chromatograph). Therefore, the degradation in the plating bath causes void formation in a via hole and causes interconnection failure. Moreover, a virtual metrology (VM) model for the bath plating degradation due to the by-product is developed using a mathematical model. VM-FDC (Fault detection and classification) using a mathematical model is performed and the interconnection failure is prevented.