CENTRALIZED SUPPLY AND IMPEDANCE MONITORING FOR DUAL-DAMASCENE COPPER BATH MANAGEMENT

摘要

This paper presents and discusses the features of a centralized copper bath management system containing an advanced process control solution that was successfully implemented in a semiconductor fabrication facility. The advanced system consolidates the monitoring, dosing and blending of the copper bath additives and is shown to provide a consistent, blended copper solution to a process plating tool via a robust, oxygen-free delivery system. Application to multiple tools to provide overall tool bath consistency is discussed. In addition, the use of electrochemical impedance spectroscopy (EIS) methodologies to help determine the overall performance quality of the plating bath is also discussed. By-product accumulation during the electroplating process is inherently part of the electrochemical process. Therefore, maintaining each additive at or around its nominal concentration does not necessarily guarantee that the electrolyte is qualified for the deposition process. EIS has been shown to follow bath degradation and can be used in the centralized bath management system as an instant bath quality indicator.