Study on PVA brush contamination for Cross-contamination in Post CMP cleaning

Abstract

After the CMP process, various residues such as slurry particles, organic contaminants, and metal contaminants are left on the wafer. For this, a process called post-CMP cleaning is essential. However, there is a problem of reverse contamination caused by remnants of the PVA brush contaminated with excessive use during the cleaning process falling back on the wafer being cleaned. Therefore, the study was conducted focusing on the difference in contamination of PVA brush according to the conditions. In this study, it was confirmed that the ceria particles were more contaminated with the PVA brush than the silica particles, and the degree of brush loading of ceria was higher as the process progressed. Using this, the contamination was analyzed quantitatively and qualitatively under various brush processing conditions. did. In addition, in this study, the reason for the ‘Break-in process’ used when changing brushes was analyzed, and it was confirmed that the contamination was quantitatively and qualitatively changed by focusing on the skin layer. Through this, it was found that the brush with the skin layer had a higher contact area than the brush without the skin layer, so the contamination was good and the reverse contamination was also higher.