Electrodeposition in all industries switches to less hazardous components in compliance to regulations. Unique trend of semiconductor industry includes emphasize on process control which enables extension of electrolyte life time and decrease of bleed and feed ratio.

Transition of interconnect technology to copper elevated challenges for polymer removal. Electrolyte has to provide efficient removal of organic material while preserving Cu surface with controlled regrowth of copper oxide. Spectroscopy in combination with electrochemical method can provide comprehensive characterization of electrolyte for concentration of major components (H2O2, H2O, organic, pH). In addition, local electrochemical analysis provides information on copper oxide removal/regrowth.

Typical bumping process includes formation of bumps through UBM copper electrodeposition, followed by deposition of tin/lead coating. Quality control of the tin or tin/lead electroplating solutions is critical to meet demands on the properties of the plated deposit, cost, and environmental issues. Even though lead is being phased-out as enemy of environment and many replacements are being tested, it is still widely used. As all electrochemical processes, tin/lead plating is a dynamic system; unless precisely controlled, concentration of consumable components and breakdown products soon gets outside of acceptable range resulting in manufacturing problems and eventually rejects. Copper Electrodeposition process for bumping is similar and somewhat less challenging than Damascene copper electrodeposition process used for the interconnects. The control of the Damascene copper process has been a focus of research by all major semiconductor companies in recent years. We have previously demonstrated an on-line controller for complete analysis of copper electroplating solutions. This paper will focus on automated on-line determination of tin/lead coatings, by reviewing analysis of up to 6 components in a commercial tin/lead electrodeposition bath. While the benchtop analysis of tin/lead solutions has been utilized for a number of years, many obstacles exist when transitioning such procedures into automated on-line system due to steps such as gravimetric or extraction procedures. While determination of metals and acid is reasonably common, measurement of proprietary organic additives remains a challenging task. Organic additives are the key ingredients in the plating solution that influence the properties and quality of the deposits. Cyclic Voltammetric Stripping (CVS) method is an established analytical technique that has long been demonstrated to be applicable to analysis of tin and tin/lead additives in various plating solutions (fluoroborate, sulfate, MSA, and PSA). Detailed description was published in an earlier paper. This paper will describe an on-line analysis of all components generally used in a tin/lead bumping process. The total automated analysis takes about 40-60 minutes with accuracy better than 10% and reproducibility better than 5%.

With damascene processing gaining acceptance in high-volume IC manufacturing, reliable analysis of copper plating baths is increasingly important. Cyclic voltammetric stripping has shown that it is an accurate and precise method for the control of the organic additives. The latest generation adds reliability, simplicity, speed, and acceptable cost of ownership.