Investigations of the Pad Trajectory Effect on the Asymmetric Profile and Arc-Shaped Scratches in Chemical Mechanical Polishing

Abstract

Research was conducted on the trajectories formed by fixed positions on the pad and how these trajectories affect the asymmetric profile and arc-shaped scratches in chemical mechanical polishing (CMP). Also investigated was whether the local glazing of the pad surface affects the asymmetric profile using the Si3N4 film and ceria slurry, whether the end point detection (EPD) window on the pad could cause a very fine asymmetry profile according to the process conditions using the poly-Si film and silica-based slurry, and the arc-shaped scratches generated in W and Cu CMP were compared with the calculated trajectories. Based on these studies, it was confirmed that the With-In-Wafer (WiW) asymmetry profile can appear and the WiW range can be rapidly changed up to 500% depending on the polish time and the speed of platen and wafer carrier head. It can further be deduced that the repetitive arc-shaped macro scratching phenomenon is caused by a fixed scratch source on the pad. To solve this problem, we suggest the prevention of abrasive aggregation and optimization of in situ conditioning. By comparing the repetitive scratch shape and the calculated trajectory, it was possible to judge the scratches that occurred.