# Hybrid CMP Slurry Supply System Using Ionization and Atomization
## 1 Introduction  
Chemical mechanical planarization (CMP) is a global planarization technique commonly employed in semiconductor manufacturing to improve the topography of wafer surfaces. It is an essential process in manufacturing multilayered and highly dense semiconductor devices. However, semiconductor manufacturing adversely affects the environment [1], and the CMP, one of the processes, also has factors that affect the environment. The slurry is an acid or a base solution that contains components, such as complexing agents, abrasives, oxidizers, and corrosion inhibitors, which can negatively impact the environment [2]. Thus, among the various CMP consumables, such as slurry, polishing pads, and conditioners, the slurry has the most unfavorable impact on the environment. Additionally, it accounts for more than 50% of the cost of the consumables in the CMP process [3]. Therefore, a reduction in slurry consumption is indispensable.  
Several studies [4; 5; 6] aimed to reduce the amount of slurry consumption by improving the slurry performance considering the types and concentrations of the chemical components. However, further improvement in the performance based on the chemical composition moderation is not feasible. Therefore, several researchers considered reducing the amount of slurry consumption by improving the low slurry-utilization efficiency of 2-22% [7].  
Initially, studies focused on the development of consumables such as pad grooves [8; 9] and retaining rings [10] to compensate for the low slurry-utilization efficiency at the wafer-pad interface. However, slurry supply systems were eventually developed as an alternative. [PERSON] et al. developed a slurry injection system that improves the slurry-utilization efficiency without reducing the material removal rate (MRR) or increasing the defects [11]. This system floats on the pad and uses multi-point injectors to supply fresh slurry uniformly while removing the used slurry. [PERSON] et al. proposed a slurry supply mechanism based on the capillary effect. In this mechanism, the slurry was supplied uniformly using a fiber array on the pad [12]. However, the aforementioned studies are limited to large and complex devices, and the effects of the systems are insignificant.  
Therefore, we propose a novel slurry supply system that can achieve excellent results when applied to any machine or material, despite its simplicity. The hybrid system ionizes the slurry through electrolysis and supplies the ionized slurry to the wafer-pad interface uniformly using a spray slurry nozzle. The ionized and atomized slurry is chemically activated and supplied uniformly to polish the wafer surfaces. This improves the MRR and uniformity while reducing the defects, such as dishing. We compared the experimental results obtained using the hybrid slurry supply system with those of the conventional slurry supply system, ionization system, and atomization system, used in the CMP processes of Cu and SiO\({}_{2}\) non-patterned wafers (NPWs). Furthermore, the step height reduction, dishing, and pitch-size dependence were determined using the hybrid slurry supply system. A significant reduction was observed in the defects in comparison with those observed in the conventional system in a Cu-patterned wafer. Thus far, only the mechanical properties of equipment and consumables or the chemical properties of slurry components have been considered to enhance the CMP performance. However, we believe that the proposed hybrid slurry supply system can contribute to performance improvement by controlling not only mechanical properties but also chemical properties.