A study on eco-friendly organic antimicrobial agents to inhibit microbial growth in copper chemical mechanical polishing slurry

Abstract

Metal CMP slurry contains various chemical additives, and some organic compounds can cause microbial growth as nutrients. Microbial growth due to slurry aging can cause various problems during CMP process, and specific research on this topic is lacking. This study evaluates the impact of microbial growth on CMP process and proposes antimicrobial agents to inhibit it. Microbial growth changes the basic properties of slurry, such as pH value and viscosity, and directly affects CMP performance. As a result of identification evaluation, various types of microbes (Gram-positive, Gram-negative bacteria and mold) were confirmed in the aged slurry. To suppress these microbes, $\epsilon$-poly-l-lysine (EPL) and nisin were proposed as environmentally friendly antimicrobial agents to replace existing biocides. The antimicrobial activities of EPL and nisin were compared by the type of microbe, and their insufficient performances were improved through optimization by combined addition. The optimized condition based on combined addition performed inhibition rate of at least 92.8 % for bacteria and mold. Furthermore, the optimized slurry was evaluated to inhibit microbial growth for >8 weeks, and it achieved maintenance of copper removal rate and surface roughness (R_a) improvement from 0.373 nm to 0.324 nm compared with the original slurry.