Applicate Tangential Flow Filtration System to Improve Post CMP-Cleaning Performance

Abstract

Chemical mechanical polishing (CMP) is one of the important process steps in semiconductor manufacturing. Several types of abrasives are used in the CMP process, among these, ceria slurry is commonly used through its excellent polishing performance in terms of oxide MRR. However, ceria particles remain on the wafer surface after polishing process as contaminants, and small ceria particles are difficult to remove from wafer surface [1]. In this respect, we focused to treat small ceria particles that interfere with the cleaning process and we applicate the tangential flow filtration (TFF) system before the CMP process. TFF system is a system for separation of particles by Brownian motion, shear-induced diffusion and the mechanism shown in Fig. In this experiment, separation of small ceria particles successfully and it was evaluated by scanning mobility particle sizer (SMPS) analysis. Furthermore, TFF system did not affect the slurry properties of particle mean diameter, pH value, and zeta potential. In this study, concentration of ceria particles on the wafer surface after CMP process were evaluated by ICP-MS analysis. We calculated the cleaning efficiency with and without TFF separation system. As a result, cleaning efficiency was improved by using TFF system. In addition, the removal rate of SiO2 was almost maintained and the deviation decreased. References [1] J. Seo, A. Gowda and S. Babu, ECS Journal of Solid State Science and Technology, 7, P243 (2018). Figure 1