슬러리 공급 방법과 첨가제가 슬러리의 안정도에 미치는 영향

Abstract

With the miniaturization of semiconductor devices, chemical mechanical planarization (CMP) is commonly employed for both the front and back end processing of such devices due to its unique global planarization capability. High stable slurry plays an important role in minimizing the process-induced particle agglomeration and ensuring a superior polishing performance. However, abrasive particles can be agglomerated during the slurry formulation and handling processes. The presence of oversize particles in the slurry is one of the main causes of defectivity during CMP of metals and dielectrics. The effects on slurry agglomeration and influence additive on slurry stability were investigated. These results indicate that the agglomeration of the slurries was found both on the external shear stress and the interparticle forces acting on the slurries. It is known that magnetically levitated centrifugal pump caused low shear flow and insignificant increase in agglomerated particles during the handling process as compared to the positive displacement pump. An increase of repulsive interparticle force corresponded to a considerable decrease in agglomerated particles during the handling process. The addition of chemical (e.g., salt, pH, surfactant and additive) into ceria slurries can influence the slurry stability and polishing performance. The slurry stability can be improved by addition of proper surfactant and additive. In this study, three different types of pumps (e.g., bellows, diaphragm and magnetically levitated centrifugal pump) were evaluated for their performance such as zeta-potential, particle mean size, specific gravity, viscosity, pH, total percent solids and concentration of large particles. Eventually, CMP slurry was improved as a function of several of additives.