CMP 후 세정 공정에서 브러쉬 및 웨이퍼 회전 속도에따른 세정액 유동 해석

Abstract

Chemical mechanical polishing (CMP) is a planarization process that mechanically removes the chemically reacted surface layer of a wafer using abrasives, thus playing a crucial role in enhancing the integration density of modern semiconductor devices. However, ensuring that all abrasives are completely removed during the post-CMP cleaning process before advancing to subsequent steps is critical. This study utilizes the improved smoothed particle hydrodynamics method to analyze the flow of a cleaning solution during post-CMP cleaning under varying brush and wafer rotation speeds. With a 3-mm gap between the brush and wafer, the velocity of the cleaning solution is found to be highly dependent on the wafer’s rotation speed, whereas the brush’s effect on flow velocity is relatively minor. In addition, the pressure of the cleaning solution tends to increase over the duration of the post-CMP cleaning, peaking at a brush rotation speed of 200 rpm. Future studies should investigate the variations in cleaning solution velocity and pressure under different brush– wafer gap conditions, as well as the effects of changes in brush and wafer rotation speeds. Research into double-sided brush cleaning, which is employed in actual post-CMP cleaning processes, is also expected to be necessary.