Reduction of process defects using a modified set-up for chemical mechanical polishing equipment

Abstract

The chemical mechanical polishing (CMP) process is widely used for global planarization of inter-metal dielectric (IMD) and inter-layer dielectric (ILD) layers for deep sub-micron technology. However, as the IMD and ILD layers get thinner, defects such as micro-scratches can lead to severe circuit failure, which affects yield. In this paper, for the improvement of the CMP process, deionized water (DIW) pressure, purified nitrogen (PN 2) gas, point of use slurry filter, and high spray bar were installed. Our experimental results show that DIW pressure and PN 2 gas factors are not related to removal rate, but they are closely related to the edge hot spot on a patterned wafer. Also, the filter installation in a CMP instrument could remarkably reduce the defects after CMP processing, it is shown that the slurry filter plays an important role in the determination of pad lifetime. However, since the slurry filter cannot completely prevent defect-causing particles from entering the system, the installation of the high spray bar of deionized water with high pressure is proposed.