The Effect of Centrifugation Method for the Large Particle Removal from CMP Slurry

Abstract

As device sizes become smaller, to achieve superior flatness which directly related to production yield after CMP (chemical mechanical planarization) process gains more importance.[1] CMP process is an extensive usage and continuing high growth rates in the semiconductor industry. The scratch due to slurry in large particle is the most challenging issue in CMP process. Even much investigation has been tried to eliminate scratches, the understanding the origins of the scratches during polishing are still needed. [2] In this study, we examined the change slurry production process to decrease the scratch by centrifugation. Fig.1 is a comparison of centrifugal separation step added to the slurry production process flow. Fig.2 shows transmission electron microscope(TEM) image of slurry particle distribution. Fig.3 shows large particle count(LPC) and quantity filtration measurement(QFM) data we proposed. According to the results, the large particles were removed by centrifugation. Fig.4 is the scratch comparison result of the normal slurry and centrifuged slurry. In experimental results, we found that compared and analyzed that the large particles were separated by measuring LPC(large particle count) and QFM(quantity filtration measurement). We also found out that the centrifuged slurry was improved in CMP through the scratch evaluation. REFERENCE 1. P. Singer, “Chemical-Mechanical Polishing : A new focus on consumable”, Semiconductor International, pp. 48-53, Feb, 1994. 2. Y. Li, Microelectronic Applications of Chemical Mechanical Planarization, Chap. 17, pp. 512-516, John Wiley & Sons, New Jersey, 2008. 3. J.-G.. Choi et al, “Analysis of scratches formed on oxide surface during chemical mechanical planarization.” Journal of the electrochemical society 157 (2) H186-H191, 2010. Figure 1